Albinism (from
LatinLatin is an Italic language originally spoken in Latium and Ancient Rome. Through the Roman conquest, Latin spread throughout the Mediterranean and a large part of Europe...
albus, "white";
see extended etymology, also called
achromia,
achromasia, or
achromatosis) is a form of
hypopigmentaryHypopigmentation is the loss of skin color. It is caused by melanocyte or melanin depletion, or a decrease in the amino acid tyrosine, which is used by melanocytes to make melanin.-Associated conditions:It is seen in:*albinism...
congenital disorderCongenital disorder involves defects in or damage to a developing fetus. It may be the result of genetic abnormalities, the intrauterine environment, errors of morphogenesis, or a chromosomal abnormality. The outcome of the disorder will further depend on complex interactions between the pre-natal...
, characterized by a partial (in
hypomelanism, also known as
hypomelanosis) or total (
amelanism or
amelanosis) lack of
melaninMelanin is a class of compounds found in plants, animals, and protists, where it serves predominantly as a pigment. The class of pigments are derivatives of the amino acid tyrosine. Many melanins are insoluble salts and show affinity to water...
pigmentBiological pigments, also known simply as pigments or biochromes are substances produced by living organisms that have a color resulting from selective color absorption. Biological pigments include plant pigments and flower pigments...
in the eyes, skin and hair, or more rarely in the eyes alone. Albinism results from inheritance of recessive alleles. The condition is known to affect mammals (including humans), fish, birds, reptiles and amphibians. While the most common term for an organism affected by albinism is "albino" (noun and adjective), the word is sometimes used in derogatory ways towards people; more neutral terms are "albinistic" (adjective) and "person with albinism" (noun). Additional clinical adjectives sometimes used to refer to animals are "albinoid" and "albinic".
It is not the same as leucism, in which all integumental pigment is at least partially absent, but the eyes retain their usual color.
Types of human albinism
Albinism is hereditary; it is not an
infectious diseaseAn infectious disease is a clinically evident disease resulting from the presence of pathogenic microbial agents, including pathogenic viruses, pathogenic bacteria, fungi, protozoa, multicellular parasites, and aberrant proteins known as prions...
and cannot be transmitted through contact,
blood transfusionBlood transfusion is the process of transferring blood or blood-based products from one person into the circulatory system of another. Blood transfusions can be life-saving in some situations, such as massive blood loss due to trauma, or can be used to replace blood lost during surgery...
s, or other vectors. The principal gene which results in albinism prevents the body from making the usual amounts of the
pigmentBiological pigments, also known simply as pigments or biochromes are substances produced by living organisms that have a color resulting from selective color absorption. Biological pigments include plant pigments and flower pigments...
melaninMelanin is a class of compounds found in plants, animals, and protists, where it serves predominantly as a pigment. The class of pigments are derivatives of the amino acid tyrosine. Many melanins are insoluble salts and show affinity to water...
. Most forms of albinism are the result of the biological inheritance of
genetically recessiveIn genetics, dominance describes a relationship between different forms of a gene at a particular physical location on a chromosome. Typical plants and animals have two sets of chromosomes, one set inherited from each parent, and are described as diploid. They therefore have two alleles at each...
alleleAn allele is one of a series of different forms of a gene. The word is a short form of allelomorph , which was used in the early days of genetics to describe variant forms of a gene detected as different phenotypes...
s (
geneA gene is the basic unit of heredity in a living organism. All living things depend on genes. Genes hold the information to build and maintain their cells and pass genetic traits to offspring...
s) passed from both parents of an individual, though some rare forms are inherited from only one parent. There are other genetic mutations which are proven to be associated with albinism. All alterations, however, lead to changes in melanin production in the body.
Albinism was formerly categorized as
tyrosinaseTyrosinase is an enzyme that catalyses the oxidation of phenols and is widespread in plants and animals...
-positive or -negative. In cases of tyrosinase-positive albinism, the
enzymeEnzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at...
tyrosinase is present. The
melanocyteMelanocytes are cells located in the bottom layer of the skin's epidermis, the middle layer of the eye , the inner ear, meninges, bones and heart that produce melanin which is a pigment.-Melanogenesis:...
s (pigment cells) are unable to produce melanin for any one of a variety of reasons that do not directly involve the tyrosinase enzyme. In tyrosinase-negative cases, either the tyrosinase enzyme is not produced or a nonfunctional version is produced. This classification has been rendered obsolete by recent research.
The chance of offspring with albinism resulting from the pairing of an organism with albinism and one without albinism is low, as discussed in more detail below. However, because organisms can be carriers of genes for albinism without exhibiting any traits, albinistic offspring can be produced by two non-albinistic parents. Albinism usually occurs with equal frequency in both genders. An exception to this is ocular albinism, because it is passed on to offspring through X-linked inheritance. Thus, males more frequently have ocular albinism as they do not have a second X chromosome.
Because organisms with albinism have skin that lacks (sufficiently or entirely) the dark pigment melanin, which helps protect the skin from
ultravioletUltraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than x-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
radiationIn physics, radiation describes any process in which energy emitted by one body travels through a medium or through space, ultimately to be absorbed by another body...
coming from the sun, they can
sunburnA sunburn is a burn to living tissue such as skin produced by overexposure to ultraviolet radiation, commonly from the sun's rays.Usual mild symptoms in humans and animals are red or reddish skin that is hot to the touch, general fatigue, and mild dizziness. An excess of UV-radiation can be...
easily from overexposure. (See
human skin colorHuman skin color can range from almost black to nearly colorless in different people. Skin color is determined primarily by the amount and type of melanin, the pigment in the skin. Variation in skin color is largely due to genetics...
for more information). Lack of melanin in the eye also results in problems with vision, related and unrelated to
photosensitivityPhotosensitivity is the amount to which an object reacts upon receiving photons, especially visible light.-Interpretation in medicine:Sensitivity of the skin to a light source can take various forms. People with particular skin types are more sensitive to sunburn...
, which are discussed further below.
Most humans and many animals with albinism appear white or very pale; the multiple types of melanin pigment are responsible for brown, black, gray, and some yellow colorations. In some humans and animals there can be a single patch or patches of skin displaying albinism. Especially
albinistic birdsAlbinism in birds is rare, occurring to any extent in perhaps one in 1800 individuals . A bird that is albino has white feathers in place of coloured ones on some portion of its body...
and reptiles, ruddy and yellow hues or other colors may be present on the entire body or in patches (as is common among pigeons), due to the presence of other pigments unaffected by albinism such as
porphyrinPorphyrins are a group of organic compounds of which many occur in nature, most well-known as the pigment in red blood cells. They are heterocyclic macrocycles characterised by the presence of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges...
s,
pteridinePteridine is a chemical compound composed of fused pyrimidine and pyrazine rings. A pteridine is also a group of heterocyclic compounds containing a wide variety of substitutions on this structure. Pterins and flavins are classes of substituted pteridines that have important biological...
s and psittacins, as well as
carotenoidCarotenoids are organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some types of fungus and some bacteria....
pigments derived from the diet. Some animals are white or pale due to
chromatophoreChromatophores are pigment-containing and light-reflecting cells found in amphibians, fish, reptiles, crustaceans, and cephalopods. They are largely responsible for generating skin and eye colour in cold-blooded animals and are generated in the neural crest during embryonic development...
(pigment cell) defects, and do not lack melanin
production, and have normal eyes; they are referred to as leucistic. The direct opposite of albinism, an unusually high level of melanin pigmentation (and sometimes absence of other types of pigment in species that have more than one), is known as
melanismMelanism is the occurrence of an increased amount of dark pigmentation in an organism, resulting from the presence of melanin...
, and results in an appearance darker than non-melanistic specimens from the same genepool. Albinism-like conditions may affect other pigments or pigment-production mechanisms in some animals (e.g. "whiteface", a lack of psittacins that can affect some parrot species.). Another is common in reptiles and amphibians: axanthism, in which xanthophore
metabolismMetabolism is the set of chemical reactions that occur in living organisms to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories. Catabolism breaks down organic matter,...
, instead of
synthesisIn chemistry, chemical synthesis is purposeful execution of chemical reactions to get a product, or several products. This happens by physical and chemical manipulations usually involving one or more reactions...
of melanin, is affected, resuling in reduction or absence of red and yellow pteridine pigments. Of all these conditions, only albinism and melanism affect humans.
The eyes of an animal with albinism occasionally appear red due to the underlying retinal blood vessels showing through where there is not enough pigment to cover them. In humans this is rarely the case, as a human eye is quite large and thus produces enough pigment to lend opacity to the eye, often colouring the iris pale blue. However, there are cases in which the eyes of an albinistic person appear red or purple, depending on the amount of pigment present.
The albinistic are generally (but see related disorders below) as healthy as the rest of their species, with growth and development occurring as normal, and albinism by itself does not cause mortality (though the lack of pigment is an elevated risk for skin cancer and other problems.) Many animals with albinism lack their protective
camouflageCamouflage is a method of crypsis that allows an otherwise visible organism or object to remain indiscernible from the surrounding environment through deception. Examples include a tiger's stripes and the battledress of a modern soldier...
and are unable to conceal themselves from their predators or prey; the survival rate of animals with albinism in the wild is usually quite low. However the novelty of albino animals has occasionally led to their protection by groups such as the
Albino Squirrel Preservation SocietyThe Albino Squirrel Preservation Society is an international collegiate organization dedicated to "fostering compassion and goodwill" toward albino squirrels...
.
Intentionally-bred albinistic strains of some animal species are commonly used as
model organismA model organism is a species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms...
s in biomedical study and experimentation. Examples include the
BALB/cBALB/c is an albino, laboratory-bred strain of the House Mouse from which a number of common substrains are derived. Now over 200 generations from their origin in New York in 1920, BALB/c mice are distributed globally, and among the most widely used inbred strains used in animal experimentation.-...
mouse and Wistar and Sprague Dawley rat strains, while albino rabbits were historically used for
Draize toxicity testingThe Draize Test is an acute toxicity test devised in 1944 by Food and Drug Administration toxicologist John H. Draize. Initially used for testing cosmetics, the procedure involves applying 0.5mL or 0.5g of a test substance to the eye or skin of a restrained, conscious animal, and leaving it for...
. Albino
axolotlThe axolotl , Ambystoma mexicanum, is the best known of the Mexican neotenic mole salamanders belonging to the Tiger Salamander complex. Larvae of this species fail to undergo metamorphosis, so the adults remain aquatic and gilled...
s, zebrafish, medaka and
frogsXenopus is a genus of highly aquatic frogs native to Sub-Saharan Africa. There are 18 species in the Xenopus genus...
are other common laboratory animals. The
yellow mutation in
fruit fliesDrosophila is a genus of small flies, belonging to the family Drosophilidae, whose members are often called "fruit flies" or more appropriately pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit...
is their version of albinism.
The incidence of albinism can be artificially increased in fish by exposing the eggs to
heavy metalsA heavy metal is a member of an ill-defined subset of elements that exhibit metallic properties, which would mainly include the transition metals, some metalloids, lanthanoids, and actinides. Many different definitions have been proposed—some based on density, some on atomic number or atomic...
.
About 1 in 17,000 human beings has some type of albinism, although up to 1 in 70 is a carrier of albinism genes.
Classification
Albinism (from
LatinLatin is an Italic language originally spoken in Latium and Ancient Rome. Through the Roman conquest, Latin spread throughout the Mediterranean and a large part of Europe...
albus, "white";
see extended etymology, also called
achromia,
achromasia, or
achromatosis) is a form of
hypopigmentaryHypopigmentation is the loss of skin color. It is caused by melanocyte or melanin depletion, or a decrease in the amino acid tyrosine, which is used by melanocytes to make melanin.-Associated conditions:It is seen in:*albinism...
congenital disorderCongenital disorder involves defects in or damage to a developing fetus. It may be the result of genetic abnormalities, the intrauterine environment, errors of morphogenesis, or a chromosomal abnormality. The outcome of the disorder will further depend on complex interactions between the pre-natal...
, characterized by a partial (in
hypomelanism, also known as
hypomelanosis) or total (
amelanism or
amelanosis) lack of
melaninMelanin is a class of compounds found in plants, animals, and protists, where it serves predominantly as a pigment. The class of pigments are derivatives of the amino acid tyrosine. Many melanins are insoluble salts and show affinity to water...
pigmentBiological pigments, also known simply as pigments or biochromes are substances produced by living organisms that have a color resulting from selective color absorption. Biological pigments include plant pigments and flower pigments...
in the eyes, skin and hair, or more rarely in the eyes alone. Albinism results from inheritance of recessive alleles. The condition is known to affect mammals (including humans), fish, birds, reptiles and amphibians. While the most common term for an organism affected by albinism is "albino" (noun and adjective), the word is sometimes used in derogatory ways towards people; more neutral terms are "albinistic" (adjective) and "person with albinism" (noun). Additional clinical adjectives sometimes used to refer to animals are "albinoid" and "albinic".
It is not the same as leucism, in which all integumental pigment is at least partially absent, but the eyes retain their usual color.
Types of human albinism
Albinism is hereditary; it is not an
infectious diseaseAn infectious disease is a clinically evident disease resulting from the presence of pathogenic microbial agents, including pathogenic viruses, pathogenic bacteria, fungi, protozoa, multicellular parasites, and aberrant proteins known as prions...
and cannot be transmitted through contact,
blood transfusionBlood transfusion is the process of transferring blood or blood-based products from one person into the circulatory system of another. Blood transfusions can be life-saving in some situations, such as massive blood loss due to trauma, or can be used to replace blood lost during surgery...
s, or other vectors. The principal gene which results in albinism prevents the body from making the usual amounts of the
pigmentBiological pigments, also known simply as pigments or biochromes are substances produced by living organisms that have a color resulting from selective color absorption. Biological pigments include plant pigments and flower pigments...
melaninMelanin is a class of compounds found in plants, animals, and protists, where it serves predominantly as a pigment. The class of pigments are derivatives of the amino acid tyrosine. Many melanins are insoluble salts and show affinity to water...
. Most forms of albinism are the result of the biological inheritance of
genetically recessiveIn genetics, dominance describes a relationship between different forms of a gene at a particular physical location on a chromosome. Typical plants and animals have two sets of chromosomes, one set inherited from each parent, and are described as diploid. They therefore have two alleles at each...
alleleAn allele is one of a series of different forms of a gene. The word is a short form of allelomorph , which was used in the early days of genetics to describe variant forms of a gene detected as different phenotypes...
s (
geneA gene is the basic unit of heredity in a living organism. All living things depend on genes. Genes hold the information to build and maintain their cells and pass genetic traits to offspring...
s) passed from both parents of an individual, though some rare forms are inherited from only one parent. There are other genetic mutations which are proven to be associated with albinism. All alterations, however, lead to changes in melanin production in the body.
Albinism was formerly categorized as
tyrosinaseTyrosinase is an enzyme that catalyses the oxidation of phenols and is widespread in plants and animals...
-positive or -negative. In cases of tyrosinase-positive albinism, the
enzymeEnzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at...
tyrosinase is present. The
melanocyteMelanocytes are cells located in the bottom layer of the skin's epidermis, the middle layer of the eye , the inner ear, meninges, bones and heart that produce melanin which is a pigment.-Melanogenesis:...
s (pigment cells) are unable to produce melanin for any one of a variety of reasons that do not directly involve the tyrosinase enzyme. In tyrosinase-negative cases, either the tyrosinase enzyme is not produced or a nonfunctional version is produced. This classification has been rendered obsolete by recent research.
The chance of offspring with albinism resulting from the pairing of an organism with albinism and one without albinism is low, as discussed in more detail below. However, because organisms can be carriers of genes for albinism without exhibiting any traits, albinistic offspring can be produced by two non-albinistic parents. Albinism usually occurs with equal frequency in both genders. An exception to this is ocular albinism, because it is passed on to offspring through X-linked inheritance. Thus, males more frequently have ocular albinism as they do not have a second X chromosome.
Because organisms with albinism have skin that lacks (sufficiently or entirely) the dark pigment melanin, which helps protect the skin from
ultravioletUltraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than x-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
radiationIn physics, radiation describes any process in which energy emitted by one body travels through a medium or through space, ultimately to be absorbed by another body...
coming from the sun, they can
sunburnA sunburn is a burn to living tissue such as skin produced by overexposure to ultraviolet radiation, commonly from the sun's rays.Usual mild symptoms in humans and animals are red or reddish skin that is hot to the touch, general fatigue, and mild dizziness. An excess of UV-radiation can be...
easily from overexposure. (See
human skin colorHuman skin color can range from almost black to nearly colorless in different people. Skin color is determined primarily by the amount and type of melanin, the pigment in the skin. Variation in skin color is largely due to genetics...
for more information). Lack of melanin in the eye also results in problems with vision, related and unrelated to
photosensitivityPhotosensitivity is the amount to which an object reacts upon receiving photons, especially visible light.-Interpretation in medicine:Sensitivity of the skin to a light source can take various forms. People with particular skin types are more sensitive to sunburn...
, which are discussed further below.
Most humans and many animals with albinism appear white or very pale; the multiple types of melanin pigment are responsible for brown, black, gray, and some yellow colorations. In some humans and animals there can be a single patch or patches of skin displaying albinism. Especially
albinistic birdsAlbinism in birds is rare, occurring to any extent in perhaps one in 1800 individuals . A bird that is albino has white feathers in place of coloured ones on some portion of its body...
and reptiles, ruddy and yellow hues or other colors may be present on the entire body or in patches (as is common among pigeons), due to the presence of other pigments unaffected by albinism such as
porphyrinPorphyrins are a group of organic compounds of which many occur in nature, most well-known as the pigment in red blood cells. They are heterocyclic macrocycles characterised by the presence of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges...
s,
pteridinePteridine is a chemical compound composed of fused pyrimidine and pyrazine rings. A pteridine is also a group of heterocyclic compounds containing a wide variety of substitutions on this structure. Pterins and flavins are classes of substituted pteridines that have important biological...
s and psittacins, as well as
carotenoidCarotenoids are organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some types of fungus and some bacteria....
pigments derived from the diet. Some animals are white or pale due to
chromatophoreChromatophores are pigment-containing and light-reflecting cells found in amphibians, fish, reptiles, crustaceans, and cephalopods. They are largely responsible for generating skin and eye colour in cold-blooded animals and are generated in the neural crest during embryonic development...
(pigment cell) defects, and do not lack melanin
production, and have normal eyes; they are referred to as leucistic. The direct opposite of albinism, an unusually high level of melanin pigmentation (and sometimes absence of other types of pigment in species that have more than one), is known as
melanismMelanism is the occurrence of an increased amount of dark pigmentation in an organism, resulting from the presence of melanin...
, and results in an appearance darker than non-melanistic specimens from the same genepool. Albinism-like conditions may affect other pigments or pigment-production mechanisms in some animals (e.g. "whiteface", a lack of psittacins that can affect some parrot species.). Another is common in reptiles and amphibians: axanthism, in which xanthophore
metabolismMetabolism is the set of chemical reactions that occur in living organisms to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories. Catabolism breaks down organic matter,...
, instead of
synthesisIn chemistry, chemical synthesis is purposeful execution of chemical reactions to get a product, or several products. This happens by physical and chemical manipulations usually involving one or more reactions...
of melanin, is affected, resuling in reduction or absence of red and yellow pteridine pigments. Of all these conditions, only albinism and melanism affect humans.
The eyes of an animal with albinism occasionally appear red due to the underlying retinal blood vessels showing through where there is not enough pigment to cover them. In humans this is rarely the case, as a human eye is quite large and thus produces enough pigment to lend opacity to the eye, often colouring the iris pale blue. However, there are cases in which the eyes of an albinistic person appear red or purple, depending on the amount of pigment present.
The albinistic are generally (but see related disorders below) as healthy as the rest of their species, with growth and development occurring as normal, and albinism by itself does not cause mortality (though the lack of pigment is an elevated risk for skin cancer and other problems.) Many animals with albinism lack their protective
camouflageCamouflage is a method of crypsis that allows an otherwise visible organism or object to remain indiscernible from the surrounding environment through deception. Examples include a tiger's stripes and the battledress of a modern soldier...
and are unable to conceal themselves from their predators or prey; the survival rate of animals with albinism in the wild is usually quite low. However the novelty of albino animals has occasionally led to their protection by groups such as the
Albino Squirrel Preservation SocietyThe Albino Squirrel Preservation Society is an international collegiate organization dedicated to "fostering compassion and goodwill" toward albino squirrels...
.
Intentionally-bred albinistic strains of some animal species are commonly used as
model organismA model organism is a species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms...
s in biomedical study and experimentation. Examples include the
BALB/cBALB/c is an albino, laboratory-bred strain of the House Mouse from which a number of common substrains are derived. Now over 200 generations from their origin in New York in 1920, BALB/c mice are distributed globally, and among the most widely used inbred strains used in animal experimentation.-...
mouse and Wistar and Sprague Dawley rat strains, while albino rabbits were historically used for
Draize toxicity testingThe Draize Test is an acute toxicity test devised in 1944 by Food and Drug Administration toxicologist John H. Draize. Initially used for testing cosmetics, the procedure involves applying 0.5mL or 0.5g of a test substance to the eye or skin of a restrained, conscious animal, and leaving it for...
. Albino
axolotlThe axolotl , Ambystoma mexicanum, is the best known of the Mexican neotenic mole salamanders belonging to the Tiger Salamander complex. Larvae of this species fail to undergo metamorphosis, so the adults remain aquatic and gilled...
s, zebrafish, medaka and
frogsXenopus is a genus of highly aquatic frogs native to Sub-Saharan Africa. There are 18 species in the Xenopus genus...
are other common laboratory animals. The
yellow mutation in
fruit fliesDrosophila is a genus of small flies, belonging to the family Drosophilidae, whose members are often called "fruit flies" or more appropriately pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit...
is their version of albinism.
The incidence of albinism can be artificially increased in fish by exposing the eggs to
heavy metalsA heavy metal is a member of an ill-defined subset of elements that exhibit metallic properties, which would mainly include the transition metals, some metalloids, lanthanoids, and actinides. Many different definitions have been proposed—some based on density, some on atomic number or atomic...
.
About 1 in 17,000 human beings has some type of albinism, although up to 1 in 70 is a carrier of albinism genes.
Classification
Albinism (from
LatinLatin is an Italic language originally spoken in Latium and Ancient Rome. Through the Roman conquest, Latin spread throughout the Mediterranean and a large part of Europe...
albus, "white";
see extended etymology, also called
achromia,
achromasia, or
achromatosis) is a form of
hypopigmentaryHypopigmentation is the loss of skin color. It is caused by melanocyte or melanin depletion, or a decrease in the amino acid tyrosine, which is used by melanocytes to make melanin.-Associated conditions:It is seen in:*albinism...
congenital disorderCongenital disorder involves defects in or damage to a developing fetus. It may be the result of genetic abnormalities, the intrauterine environment, errors of morphogenesis, or a chromosomal abnormality. The outcome of the disorder will further depend on complex interactions between the pre-natal...
, characterized by a partial (in
hypomelanism, also known as
hypomelanosis) or total (
amelanism or
amelanosis) lack of
melaninMelanin is a class of compounds found in plants, animals, and protists, where it serves predominantly as a pigment. The class of pigments are derivatives of the amino acid tyrosine. Many melanins are insoluble salts and show affinity to water...
pigmentBiological pigments, also known simply as pigments or biochromes are substances produced by living organisms that have a color resulting from selective color absorption. Biological pigments include plant pigments and flower pigments...
in the eyes, skin and hair, or more rarely in the eyes alone. Albinism results from inheritance of recessive alleles. The condition is known to affect mammals (including humans), fish, birds, reptiles and amphibians. While the most common term for an organism affected by albinism is "albino" (noun and adjective), the word is sometimes used in derogatory ways towards people; more neutral terms are "albinistic" (adjective) and "person with albinism" (noun). Additional clinical adjectives sometimes used to refer to animals are "albinoid" and "albinic".
It is not the same as leucism, in which all integumental pigment is at least partially absent, but the eyes retain their usual color.
Types of human albinism
Albinism is hereditary; it is not an
infectious diseaseAn infectious disease is a clinically evident disease resulting from the presence of pathogenic microbial agents, including pathogenic viruses, pathogenic bacteria, fungi, protozoa, multicellular parasites, and aberrant proteins known as prions...
and cannot be transmitted through contact,
blood transfusionBlood transfusion is the process of transferring blood or blood-based products from one person into the circulatory system of another. Blood transfusions can be life-saving in some situations, such as massive blood loss due to trauma, or can be used to replace blood lost during surgery...
s, or other vectors. The principal gene which results in albinism prevents the body from making the usual amounts of the
pigmentBiological pigments, also known simply as pigments or biochromes are substances produced by living organisms that have a color resulting from selective color absorption. Biological pigments include plant pigments and flower pigments...
melaninMelanin is a class of compounds found in plants, animals, and protists, where it serves predominantly as a pigment. The class of pigments are derivatives of the amino acid tyrosine. Many melanins are insoluble salts and show affinity to water...
. Most forms of albinism are the result of the biological inheritance of
genetically recessiveIn genetics, dominance describes a relationship between different forms of a gene at a particular physical location on a chromosome. Typical plants and animals have two sets of chromosomes, one set inherited from each parent, and are described as diploid. They therefore have two alleles at each...
alleleAn allele is one of a series of different forms of a gene. The word is a short form of allelomorph , which was used in the early days of genetics to describe variant forms of a gene detected as different phenotypes...
s (
geneA gene is the basic unit of heredity in a living organism. All living things depend on genes. Genes hold the information to build and maintain their cells and pass genetic traits to offspring...
s) passed from both parents of an individual, though some rare forms are inherited from only one parent. There are other genetic mutations which are proven to be associated with albinism. All alterations, however, lead to changes in melanin production in the body.
Albinism was formerly categorized as
tyrosinaseTyrosinase is an enzyme that catalyses the oxidation of phenols and is widespread in plants and animals...
-positive or -negative. In cases of tyrosinase-positive albinism, the
enzymeEnzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at...
tyrosinase is present. The
melanocyteMelanocytes are cells located in the bottom layer of the skin's epidermis, the middle layer of the eye , the inner ear, meninges, bones and heart that produce melanin which is a pigment.-Melanogenesis:...
s (pigment cells) are unable to produce melanin for any one of a variety of reasons that do not directly involve the tyrosinase enzyme. In tyrosinase-negative cases, either the tyrosinase enzyme is not produced or a nonfunctional version is produced. This classification has been rendered obsolete by recent research.
The chance of offspring with albinism resulting from the pairing of an organism with albinism and one without albinism is low, as discussed in more detail below. However, because organisms can be carriers of genes for albinism without exhibiting any traits, albinistic offspring can be produced by two non-albinistic parents. Albinism usually occurs with equal frequency in both genders. An exception to this is ocular albinism, because it is passed on to offspring through X-linked inheritance. Thus, males more frequently have ocular albinism as they do not have a second X chromosome.
Because organisms with albinism have skin that lacks (sufficiently or entirely) the dark pigment melanin, which helps protect the skin from
ultravioletUltraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than x-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
radiationIn physics, radiation describes any process in which energy emitted by one body travels through a medium or through space, ultimately to be absorbed by another body...
coming from the sun, they can
sunburnA sunburn is a burn to living tissue such as skin produced by overexposure to ultraviolet radiation, commonly from the sun's rays.Usual mild symptoms in humans and animals are red or reddish skin that is hot to the touch, general fatigue, and mild dizziness. An excess of UV-radiation can be...
easily from overexposure. (See
human skin colorHuman skin color can range from almost black to nearly colorless in different people. Skin color is determined primarily by the amount and type of melanin, the pigment in the skin. Variation in skin color is largely due to genetics...
for more information). Lack of melanin in the eye also results in problems with vision, related and unrelated to
photosensitivityPhotosensitivity is the amount to which an object reacts upon receiving photons, especially visible light.-Interpretation in medicine:Sensitivity of the skin to a light source can take various forms. People with particular skin types are more sensitive to sunburn...
, which are discussed further below.
Most humans and many animals with albinism appear white or very pale; the multiple types of melanin pigment are responsible for brown, black, gray, and some yellow colorations. In some humans and animals there can be a single patch or patches of skin displaying albinism. Especially
albinistic birdsAlbinism in birds is rare, occurring to any extent in perhaps one in 1800 individuals . A bird that is albino has white feathers in place of coloured ones on some portion of its body...
and reptiles, ruddy and yellow hues or other colors may be present on the entire body or in patches (as is common among pigeons), due to the presence of other pigments unaffected by albinism such as
porphyrinPorphyrins are a group of organic compounds of which many occur in nature, most well-known as the pigment in red blood cells. They are heterocyclic macrocycles characterised by the presence of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges...
s,
pteridinePteridine is a chemical compound composed of fused pyrimidine and pyrazine rings. A pteridine is also a group of heterocyclic compounds containing a wide variety of substitutions on this structure. Pterins and flavins are classes of substituted pteridines that have important biological...
s and psittacins, as well as
carotenoidCarotenoids are organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some types of fungus and some bacteria....
pigments derived from the diet. Some animals are white or pale due to
chromatophoreChromatophores are pigment-containing and light-reflecting cells found in amphibians, fish, reptiles, crustaceans, and cephalopods. They are largely responsible for generating skin and eye colour in cold-blooded animals and are generated in the neural crest during embryonic development...
(pigment cell) defects, and do not lack melanin
production, and have normal eyes; they are referred to as leucistic. The direct opposite of albinism, an unusually high level of melanin pigmentation (and sometimes absence of other types of pigment in species that have more than one), is known as
melanismMelanism is the occurrence of an increased amount of dark pigmentation in an organism, resulting from the presence of melanin...
, and results in an appearance darker than non-melanistic specimens from the same genepool. Albinism-like conditions may affect other pigments or pigment-production mechanisms in some animals (e.g. "whiteface", a lack of psittacins that can affect some parrot species.). Another is common in reptiles and amphibians: axanthism, in which xanthophore
metabolismMetabolism is the set of chemical reactions that occur in living organisms to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories. Catabolism breaks down organic matter,...
, instead of
synthesisIn chemistry, chemical synthesis is purposeful execution of chemical reactions to get a product, or several products. This happens by physical and chemical manipulations usually involving one or more reactions...
of melanin, is affected, resuling in reduction or absence of red and yellow pteridine pigments. Of all these conditions, only albinism and melanism affect humans.
The eyes of an animal with albinism occasionally appear red due to the underlying retinal blood vessels showing through where there is not enough pigment to cover them. In humans this is rarely the case, as a human eye is quite large and thus produces enough pigment to lend opacity to the eye, often colouring the iris pale blue. However, there are cases in which the eyes of an albinistic person appear red or purple, depending on the amount of pigment present.
The albinistic are generally (but see related disorders below) as healthy as the rest of their species, with growth and development occurring as normal, and albinism by itself does not cause mortality (though the lack of pigment is an elevated risk for skin cancer and other problems.) Many animals with albinism lack their protective
camouflageCamouflage is a method of crypsis that allows an otherwise visible organism or object to remain indiscernible from the surrounding environment through deception. Examples include a tiger's stripes and the battledress of a modern soldier...
and are unable to conceal themselves from their predators or prey; the survival rate of animals with albinism in the wild is usually quite low. However the novelty of albino animals has occasionally led to their protection by groups such as the
Albino Squirrel Preservation SocietyThe Albino Squirrel Preservation Society is an international collegiate organization dedicated to "fostering compassion and goodwill" toward albino squirrels...
.
Intentionally-bred albinistic strains of some animal species are commonly used as
model organismA model organism is a species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms...
s in biomedical study and experimentation. Examples include the
BALB/cBALB/c is an albino, laboratory-bred strain of the House Mouse from which a number of common substrains are derived. Now over 200 generations from their origin in New York in 1920, BALB/c mice are distributed globally, and among the most widely used inbred strains used in animal experimentation.-...
mouse and Wistar and Sprague Dawley rat strains, while albino rabbits were historically used for
Draize toxicity testingThe Draize Test is an acute toxicity test devised in 1944 by Food and Drug Administration toxicologist John H. Draize. Initially used for testing cosmetics, the procedure involves applying 0.5mL or 0.5g of a test substance to the eye or skin of a restrained, conscious animal, and leaving it for...
. Albino
axolotlThe axolotl , Ambystoma mexicanum, is the best known of the Mexican neotenic mole salamanders belonging to the Tiger Salamander complex. Larvae of this species fail to undergo metamorphosis, so the adults remain aquatic and gilled...
s, zebrafish, medaka and
frogsXenopus is a genus of highly aquatic frogs native to Sub-Saharan Africa. There are 18 species in the Xenopus genus...
are other common laboratory animals. The
yellow mutation in
fruit fliesDrosophila is a genus of small flies, belonging to the family Drosophilidae, whose members are often called "fruit flies" or more appropriately pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit...
is their version of albinism.
The incidence of albinism can be artificially increased in fish by exposing the eggs to
heavy metalsA heavy metal is a member of an ill-defined subset of elements that exhibit metallic properties, which would mainly include the transition metals, some metalloids, lanthanoids, and actinides. Many different definitions have been proposed—some based on density, some on atomic number or atomic...
.
About 1 in 17,000 human beings has some type of albinism, although up to 1 in 70 is a carrier of albinism genes.
Classification
There are two main categories of albinism in humans:
- In oculocutaneous albinism
Oculocutaneous albinism is a form of albinism involving the eyes , skin , and according to some definitions, the hair as well....
(despite its Latin-derived name meaning "eye-and-skin" albinism), pigment is lacking in the eyes, skin and hair. (The equivalent mutation in non-humans also results in lack of melanin in the fur, scales or feathers.) People with oculocutaneous albinism can have anywhere from no pigment at all to almost-normal levels.
- In ocular albinism
Ocular albinism is a form of albinism which, in contrast to oculocutaneous albinism, presents primarily in the eyes. There are multiple forms of ocular albinism, which are clinically similar....
, only the eyes lack pigment. People who have ocular albinism have generally normal skin and hair color, although it is typically lighter than either parent. Many even have a normal eye appearance.
Other conditions include albinism as part of their presentation. These include
Hermansky-Pudlak syndromeHermansky–Pudlak syndrome is a rare autosomal recessive disorder which results in oculocutaneous albinism , bleeding problems due to a platelet abnormality , and storage of an abnormal fat-protein compound .There are eight classic forms of the disorder, based on the genetic mutation...
,
Chediak-Higashi syndromeChediak–Higashi syndrome is a rare autosomal recessive disorder that affects multiple systems of the body, and arises from a mutation in the lysosomal trafficking regulator gene, LYST. It occurs in humans, cattle, white tigers, blue Persian cats and the only known captive albino...
,
Griscelli syndromeGriscelli syndrome is a rare autosomal recessive disorder characterized by albinism with immunodeficiency, that usually causes death by early childhood.-Types:...
,
Waardenburg syndromeWaardenburg syndrome or Waardenburg-Klein syndrome is a rare genetic disorder most often characterized by varying degrees of deafness, minor defects in structures arising from the neural crest, and pigmentation anomalies.-Eponyms and classification:...
, and
Tietz syndromeTietz syndrome is a condition characterized by deafness and albinism.Tietz syndrome was characterized in 1923.-Causes:It is due to a mutation in chromosome 3, in the microphthalmia-associated transcription factor ....
. These conditions are sometimes classified with albinism. Several have sub-types. Some are easily distinguished by appearance, but in most cases genetic testing is the only way to be certain.
Symptoms and conditions associated with albinism
Genetic testingGenetic testing allows the genetic diagnosis of vulnerabilities to inherit diseases, and can also be used to determine a child's paternity or a person's ancestry. Normally, every person carries two copies of every gene, one inherited from their mother, one inherited from their father. The human...
can confirm albinism and what variety it is, but offers no medical benefits except in the cases of non-OCA disorders (see below) that cause albinism
along with other medical problems which may be treatable. The
symptoms of albinism can be treated by various methods detailed below.
Eye conditions common in albinism may include:
- Nystagmus, irregular rapid movement of the eyes back and forth, or in circular motion.
- Strabismus
Strabismus is a condition in which the eyes are not properly aligned with each other...
, eye misalignment ("crossed eyes" or "lazy eye").
- Refractive errors such as myopia
Myopia , also called nearsightedness or shortsightedness, is a refractive defect of the eye in which collimated light produces image focus in front of the retina when accommodation is relaxed....
or hyperopiaHyperopia, also known as farsightedness, longsightedness or hypermetropia, is a defect of vision caused by an imperfection in the eye , causing difficulty focusing on near objects, and in extreme cases causing a sufferer to be unable to focus on objects at any distance...
and especially astigmatismAstigmatism is an optical defect in which vision is blurred due to the inability of the optics of the eye to focus a point object into a sharp focused image on the retina. This may be due to an irregular or toric curvature of the cornea or lens. There are two types of astigmatism: regular and...
are more likely
- Photophobia
Photophobia is a symptom of excessive sensitivity to light and the aversion to sunlight or well-lit places. In ordinary medical terms photophobia is not a morbid fear, but an experience of discomfort or pain to the eyes due to light exposure....
, hypersensitivityHypersensitivity refers to undesirable reactions produced by the normal immune system. Hypersensitivity reactions require a pre-sensitized state of the host. The four-group classification was expounded by P. H. G...
to bright light and glare.
- Macular hypoplasia
Macular hypoplasia, also known as fovea hypoplasia, is a rare medical condition involving the underdevelopment of the macula.The macula is a small area on the retina responsible for seeing in detail....
, underdevelopment of the foveaThe term fovea comes from the Latin, meaning pit or pitfall. As an anatomical term, there are several foveae around the body, including in the head of the femur.Fovea of the eye=...
, the center of the retinaThe vertebrate retina is a light sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
- Optic nerve hypoplasia
Optic nerve hypoplasia is a medical condition that results in underdevelopment of the optic nerve.Optic nerve hypoplasia is the most common congenital optic disc anomaly in which the optic disc appears abnormally small, due to the fact that not all the optic nerve axons have developed...
, underdevelopment of the optic nerve
- Abnormal decussation (crossing) of the optic nerve fibers in the optic chiasm
The optic chiasm or optic chiasma is the part of the brain where the optic nerves partially cross...
- Amblyopia
Amblyopia, otherwise known as lazy eye, is a disorder of the visual system that is characterized by poor or indistinct vision in an eye that is otherwise physically normal, or out of proportion to associated structural abnormalities...
, decrease in acuity of one or both eyes due to poor transmission to the brain, often due to other conditions such as strabismusStrabismus is a condition in which the eyes are not properly aligned with each other...
.
Organisms with albinism usually have impaired vision due to one or more of the listed conditions. While a person with albinism may suffer from common refractive errors like nearsightedness or farsightedness, the visual problems particularly associated with albinism arise from a poorly-developed retinal pigment epithelium (RPE) due to the lack of melanin. This degenerate RPE causes foveal
hypoplasiaHypoplasia is underdevelopment or incomplete development of a tissue or organ. Although the term is not always used precisely, it properly refers to an inadequate or below-normal number of cells. Hypoplasia is similar to aplasia, but less severe. It is technically not the opposite of hyperplasia...
(a failure in the development of normal
foveaThe term fovea comes from the Latin, meaning pit or pitfall. As an anatomical term, there are several foveae around the body, including in the head of the femur.Fovea of the eye=...
e), which results in eccentric fixation and lower visual acuity, and often a minor level of strabismus. Nystagmus is usually seen, as is
photophobiaPhotophobia is a symptom of excessive sensitivity to light and the aversion to sunlight or well-lit places. In ordinary medical terms photophobia is not a morbid fear, but an experience of discomfort or pain to the eyes due to light exposure....
or light sensitivity (see below).
The
irisThe iris is a membrane in the eye, responsible for controlling the diameter and size of the pupil and the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel...
is a
sphincterA sphincter is a structure, usually a circular muscle, that normally maintains constriction of a natural body passage or orifice and which relaxes as required by normal physiological functioning...
with pigmented tissue (which makes up the color of the eyes) that contracts to limit the amount of light that can enter through the pupil and relaxes again to allow for better vision in darkness. This mechanism can be observed in humans and mammals (like in cat's eyes) and is needed because too much light is uncomfortable or even painful and decreases vision. In people with albinism, the iris does not have enough pigment to block the light, thus the decrease of pupil diameter is only partially successful in reducing the amount of light that enters the eye. Additionally, the improper development of the RPE, which in normal eyes absorbs most of the reflected sunlight, further increases glare due to light scattering within the eye. The resulting sensitivity (photophobia) generally leads to a dislike of and discomfort in bright light, but does not prevent people with albinism enjoying the outdoors, especially when using sunglasses and/or brimmed hats.
The lack of pigment also makes the skin unusually sensitive to sunlight and thus susceptible to
sunburnA sunburn is a burn to living tissue such as skin produced by overexposure to ultraviolet radiation, commonly from the sun's rays.Usual mild symptoms in humans and animals are red or reddish skin that is hot to the touch, general fatigue, and mild dizziness. An excess of UV-radiation can be...
, so people with albinism should either avoid prolonged exposure to bright sunlight or protect their skin.
Treatment of the symptoms
Albinism is a condition that cannot be "cured", but small things can be done to improve the quality of life for those affected. Most importantly to improve vision, protect the eyes from bright lights, and avoid skin damage from sunlight. The extent and success rate of these measures depend on the type of albinism and severity of the symptoms; in particular, people with ocular albinism are likely to have normally-pigmented skin, and thus do not need to take special precautions against skin damage.
Surgical treatment
For the most part, treatment of the eye conditions consists of visual rehabilitation. Surgery is possible on the ocular muscles to decrease nystagmus,
strabismusStrabismus is a condition in which the eyes are not properly aligned with each other...
and common refractive errors like
astigmatismAstigmatism is an optical defect in which vision is blurred due to the inability of the optics of the eye to focus a point object into a sharp focused image on the retina. This may be due to an irregular or toric curvature of the cornea or lens. There are two types of astigmatism: regular and...
. Strabismus surgery may improve the appearance of the eyes. Nystagmus-damping surgery can also be performed, to reduce the "shaking" of the eyes back and forth. The effectiveness of all these procedures varies greatly and depends on individual circumstances. More importantly, since surgery will not restore a normal RPE or foveae, surgery will not provide fine binocular vision. In the case of
esotropiaEsotropia is a form of strabismus, or "squint", in which one or both eyes turns inward. The condition can be constantly present, or occur intermittently, and can give the affected individual a "cross-eyed" appearance...
(the "crossed eyes" form of strabismus), surgery may help vision by expanding the
visual fieldThe term visual field is sometimes used as a synonym to field of view, though they do not designate the same thing. The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments", while 'field of view' "refers to the physical...
(the area that the eyes can see while looking at one point).
Vision aids
GlassesGlasses are frames bearing lenses worn in front of the eyes, normally for vision correction, eye protection, or for protection from UV rays....
and other vision aids, large-print materials and
closed captioningClosed captioning is a term describing several systems developed to display text on a television or video screen to provide additional or interpretive information to viewers who wish to access it...
, as well as bright but angled reading lights, can help individuals with albinism, even though their vision cannot be corrected completely. Some albinistic people do well using
bifocalsBifocals are eyeglasses with two distinct optical powers. Bifocals are most commonly prescribed to people with presbyopia who also require a correction for myopia, hypermetropia, and/or astigmatism.-History:...
(with a strong reading lens), prescription reading glasses, and/or hand-held devices such as
magnifiersA magnifying glass is a convex lens which is used to produce a magnified image of an object. The lens is usually mounted in a frame with a handle ....
or
monocularA monocular is a modified refracting telescope used to magnify the images of distant objects by passing light through a series of lenses and prisms; the use of prisms results in a lightweight telescope...
s( a very simple telescope). Contact lenses may be colored to block light transmission through the iris. Some use
biopticsBioptics, also known as a bioptic in the singular, and sometimes more formally termed a bioptic telescope, is a term for a pair of vision-enhancement lenses with extreme magnification, used to improve distance vision for those with severely impaired eyesight, especially those with albinism...
, glasses which have small telescopes mounted on, in, or behind their regular lenses, so that they can look through either the regular lens or the telescope. Newer designs of bioptics use smaller light-weight lenses. Some US states allow the use of bioptic telescopes for driving motor vehicles. (See also
NOAHNoah was, according to the Bible, the tenth and last of the antediluvian Patriarchs; and a prophet according to the Qur'an...
bulletin "Low Vision Aids".)
Although still disputed among the experts, many
ophthalmologistsOphthalmology is a branch of medicine which deals with the diseases and surgery of the visual pathways, including the eye, hairs, and areas surrounding the eye, such as the lacrimal system and eyelids. The term ophthalmologist is an eye specialist for medical and surgical problems...
recommend the use of glasses from early childhood onward to allow the eyes the best development possible.
OptometristsOptometry is a health care profession concerned with eyes and related structures, as well as vision, visual systems, and vision information processing in humans....
or ophthalmologists who are experienced in working with
low visionLow vision is a subspecialty within the professions of optometry and ophthalmology dealing with individuals who have reduced vision even when using the best possible spectacle or contact lens correction available. It can be a result of either congenital disease Low vision is a subspecialty within...
patients can recommend various optical aids. Some low-vision clinics provide these aids on trial loan, with instruction in their use.
Sun protection
It is vital that people with albinism use sunscreen when exposed to sunlight to prevent premature skin aging or
skin cancerSkin cancer is a malignant growth on the skin which can have many causes. The most common skin cancers are basal cell cancer, squamous cell cancer, and melanoma. Skin cancer generally develops in the epidermis , so a tumor is usually clearly visible. This makes most skin cancers detectable in the...
. This poses a problem for those who cannot afford
sunscreenSunscreen is a lotion, spray, gel or other topical product that absorbs or reflects some of the sun's ultraviolet radiation on the skin exposed to sunlight and thus helps protect against sunburn....
, especially in regions with high exposure to sunlight, as in Africa.
Use of
sunglassesSunglasses or sun glasses are a form of protective eyewear that usually enclose or protect the eye pupil in order to prevent strong light, ultraviolet rays, and increasingly, blue light from penetrating...
and hats with wide brims can make the glare outside bearable. Other things that can help people with albinism are avoiding sudden changes of the lighting situation (switching the light on in complete darkness), using dimmable switches and adding tint to car windows or blinds to normal windows. Lights should be yellowish rather than white and not point towards the usual position of a person with albinism (like their seat at a table).
Misconceptions
While some of the very rare albinism disorders that are coupled with deafness and immunodeficiency, like
Chediak-Higashi SyndromeChediak–Higashi syndrome is a rare autosomal recessive disorder that affects multiple systems of the body, and arises from a mutation in the lysosomal trafficking regulator gene, LYST. It occurs in humans, cattle, white tigers, blue Persian cats and the only known captive albino...
, appear to be linked with inbreeding, the vast majority of sufferers of common albinism are not the product of such unions; the more usual albinism genes are widespread enough that they can easily produce albinistic offspring from parents who are not related.
A common misconception is that albinistic individuals of a species are sterile, but they are in fact fully capable of reproducing. It is also thought by many that people with albinism live short life spans. This is not true in general, but may be a distorted view of a more reasonable fact that people with albinism have a higher risk of skin cancer if they do not use proper skin protection when in the sun. (Some very rare variants of albinism are lethal by adulthood or sooner, but they are so little-known by the general public that they are unlikely to have contributed to this belief.)
It has also been misunderstood that a person or other animal with albinism will become blind halfway through life; this is incorrect.
Not all albinos are photophobic, but some tend to be.
Culture
In physical terms, humans with albinism commonly have vision problems and need sun protection. But they also face
socialSociety or human society is the manner or condition in which the members of a community live together for their mutual benefit. By extension, society denotes the people of a region or country, sometimes even the world, taken as a whole....
and
culturalCulture is a term that has different meanings. For example, in 1952, Alfred Kroeber and Clyde Kluckhohn compiled a list of 164 definitions of "culture" in Culture: A Critical Review of Concepts and Definitions...
challenges (even threats) as the condition is often a source of ridicule, discrimination, or even fear and violence. Cultures around the world have developed many beliefs regarding people with albinism. This folklore ranges from harmless myth to dangerous superstitions that cost human lives.
In African countries such as
TanzaniaThe United Republic of Tanzania is a country in central East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi and the Democratic Republic of the Congo to the west, and Zambia, Malawi and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.The United...
and
BurundiBurundi , officially the Republic of Burundi, is a country in the Great Lakes region of Eastern Africa bordered by Rwanda to the north, Tanzania to the east and south, and the Democratic Republic of the Congo to the west. Its size is just under 28,000 km² with an estimated population of...
, there has been an unprecedented rise in
witchcraftWitchcraft, in various historical, anthropological, religious and mythological contexts, is the use of certain kinds of supernatural or magical powers. Witchcraft can refer to the use of such powers in order to inflict harm or damage upon members of a community or their property...
-related killings of albino people in recent years. This is because albino body parts are used in potions sold by
witchdoctorErin Johnson, better known as Witchdoctor, is an established member of Atlanta’s Dungeon Family collective which includes members such as Goodie Mob, OutKast, Cee-Lo , Big Rube, & many others...
s. Numerous authenticated incidents have occurred in Africa during the 21st Century. For example, in Tanzania, in September 2009, three men were convicted of killing a 14 year old albino boy and severing his legs in order to sell them for witchcraft purposes.
Other examples: In
ZimbabweZimbabwe , is a landlocked country located in the southern part of the continent of Africa, between the Zambezi and Limpopo rivers...
, belief that sex with an albinistic woman will cure a man of
HIVHuman immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections. Infection with HIV occurs by the transfer of blood, semen, vaginal fluid,...
has led to
rapeRape, also referred to as sexual assault, is an assault by a person involving sexual intercourse with or without sexual penetration of another person without that person's consent....
s (and subsequent HIV infections). In
JamaicaJamaica is an island nation of the Greater Antilles, in length and as much as in width, amounting to 11,100 km
2. It is situated in the Caribbean Sea, about south of Cuba, and west of Hispaniola, the island harboring the nation-states Haiti and the Dominican Republic...
, the albinistic have long been degraded, and regarded as "
curseA curse is any expressed wish that some form of adversity or unhappiness will befall another person or persons. In particular, a wish that harm or hurt will be inflicted by any supernatural power, such as a spell, a prayer, an imprecation, an execration, magic, witchcraft, a god, a natural force,...
d". Severe discrimination almost always happens in less developed countries where the general scientific knowledge of such occurrences are not widespread and superstition takes hold. It is also more frequent in countries where the skin color varies from people with albinism the most likely because they are more easily differentiated from the general population.
Portrayals of people with albinism in
literatureLiterature is the art of written works. Literally translated, the word means "acquaintance with letters" , and therefore the academic study of literature is known as Letters...
and
filmFilm encompasses individual motion pictures, the field of film as an art form, and the motion picture industry. Films are produced by recording images from the world with cameras, or by creating images using animation techniques or visual effects....
s have historically rarely been positive. This fact is sometimes referred to as the
"evil albino" stereotype, or
albino bias. While this stereotype is common, in recent years a few more positive roles have also been cast for mock-albino actors and occasionally genuinely albinistic ones.
A number of real people with albinism have become famous, including historical figures such as
Emperor Seineiwas the 22nd emperor of Japan, according to the traditional order of succession. No firm dates can be assigned to this emperor's life or reign, but Seinei is thought to have ruled the country during the late 5th century. There is an overall paucity of information about him.According to Kojiki...
of Japan, and Oxford don
William Archibald SpoonerWilliam Archibald Spooner was a famous Oxford don after whom is named a linguistic phenomenon, spoonerism.-Biography:...
; actor/comedian
Victor VarnadoVictor Varnado is an American standup comedian and actor. Born in Gary, Indiana, he is African American and is albinistic. He grew up in Huntsville, Alabama, later moving to Minneapolis, Minnesota.-Career:...
; musicians such as
JohnnyJohn Dawson "Johnny" Winter III is an American blues guitarist, singer and producer.Johnny and Edgar Winter were nurtured at an early age by their parents in their musical pursuits. Johnny Winter is known for his southern blues and rock and roll style, as well as his physical appearance...
and
Edgar WinterEdgar Holland Winter is an American musician. Edgar is a multi-instrumentalist, performing on the keyboards, and as a vocalist, saxophonist and percussionist, well-versed in jazz, blues and rock. He was most successful in the 1970s with his band The Edgar Winter Group...
,
Salif KeitaSalif Keita is an internationally recognized afro-pop singer-songwriter from Mali. He is unique not only because of his reputation as the Golden Voice of Africa, but because he has albinism and is a direct descendant of the founder of the Mali Empire, Sundiata Keita...
,
Winston "King Yellowman" FosterYellowman is a Jamaican reggae and dancehall deejay, widely known as King Yellowman...
,
Brother AliAli Newman , better known by the stage name Brother Ali, is an American hip hop artist.-Personal Life:...
,Goldie of Ghood Ent and
Willie "Piano Red" PerrymanWilliam "Willie" Lee Perryman , who was usually known professionally as Piano Red and later in life as Dr. Feelgood, was an American blues musician, the first to hit the pop music charts. He was a self-taught pianist who played in the barrelhouse blues style...
; even a fashion model,
Connie ChiuConnie Chiu is a Chinese albinistic fashion model.Chiu was born in Hong Kong to a Chinese family. Like many people with albinism, she has to protect her photosensitive eyes and skin from the sunlight...
.
There have also been some famed albino animals, including Migaloo, a
Humpback WhaleThe humpback whale is a baleen whale. One of the larger rorqual species, adults range in length from and weigh approximately . The humpback has a distinctive body shape, with unusually long pectoral fins and a knobbly head. It is an acrobatic animal, often breaching and slapping the water...
off the coast of Australia; Snowflake, a gorilla from a zoo in
BarcelonaBarcelona is the capital, most populous city of the Autonomous Community of Catalonia and the second largest city in Spain, with a population of 1,615,908 in 2008. It is the 11th-most populous municipality in the European Union and sixth-most populous urban area in the European Union after Paris,...
; Snowdrop, a
Bristol ZooBristol Zoo is a zoo in the city of Bristol in South West England. The zoo's stated mission is "Bristol Zoo Gardens maintains and defends biodiversity through breeding endangered species, conserving threatened species and habitats and promoting a wider understanding of the natural...
penguinPenguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers...
; a pink
dolphinDolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in seventeen genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly...
in
LouisianaThe State of Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state divided into parishes, which are local governments equivalent to counties...
and the
Sperm WhaleThe sperm whale, , is a species of marine mammal in the order cetacea, a toothed whale with the largest brain of any animal. The whale was named after the milky-white waxy substance, spermaceti, found in its head and originally mistaken for sperm...
Mocha DickMocha Dick was a notorious male Sperm Whale that lived in the Pacific Ocean in the early 19th century, usually encountered in the waters near the island of Mocha, off southern Chile...
, the inspiration for Herman Melville's novel
Moby-DickMoby-Dick is a classic novel published in 1851 by American author Herman Melville. Originally misunderstood by contemporary audiences and critics, Moby-Dick is now often referred to as "The Great American Novel" and is considered one of the treasures of world literature...
.
See also
- Albinism in popular culture
- Albinism in birds
Albinism in birds is rare, occurring to any extent in perhaps one in 1800 individuals . A bird that is albino has white feathers in place of coloured ones on some portion of its body...
- Leucism, a condition similar to albinism in animals, characterized by reduced pigmentation in general
- Melanism
Melanism is the occurrence of an increased amount of dark pigmentation in an organism, resulting from the presence of melanin...
(or melanosis), unusually dark melanin pigmentation
- Xanthochromism
Xanthochromism is a term that may be applied to birds, fish and other animals whose colouration is unusually yellow through an excess of yellow pigment, or possibly a loss of darker pigments that allows yellow pigment to be unusually dominant. It is often associated with the lack of usual red...
, unusually yellow pigmentation
- Vitiligo
Vitiligo is a chronic disorder that causes depigmentation in patches of skin. It occurs when the melanocytes, the cells responsible for skin pigmentation which are derived from the neural crest, die or are unable to function. The precise pathogenesis, or cause, of vitiligo is complex and not yet...
(or leukoderma), the patchy loss of skin pigmentation
- Ukerewe Island
Ukerewe is the largest island in Lake Victoria, the largest inland island in Africa, and the seventh largest lake island in the world, with an area of about 530 km²...
- List of Mendelian traits in humans
- Human variability
Human variability, or human variation, is the range of possible values for any measurable characteristic, physical or mental, of human beings. Differences can be trivial or important, transient or permanent, voluntary or involuntary, congenital or acquired, genetic or environmental...
- Albinism–deafness syndrome
Albinism–deafness syndrome is a condition characterized by congenital neural deafness and a severe or extreme piebald-like phenotype with extensive areas of hypopigmentation....
Albinism support organizations
- Positive Exposure—Non-profit organization founded by photographer Rick Guidotti, "dedicated to celebrating the spirit of difference". Focuses on genetic conditions, especially albinism.
- NOAH—National Organization for Albinism and Hypopigmentation (USA); also has an online support group
- International Albinism Center (research project based at the University of Minnesota, USA)
- Albinism Fellowship (UK and Ireland)
- AFA—Albinism Fellowship of Australia
- Albino Alliance A support group/forum for people living with albinism in Australia
- TAF—The Albino Foundation (Nigeria & USA)
- ALBA—Asociación de Ayuda a Personas con Albinismo [Aid Association to Persons with Albinism] (Spain)
- OLA—Organización Latinoamericana de Albinismo [Latin-American Albinism Organization] (Mexico)
- Albinizm.ru community site
- Hermansky-Pudlak Syndrome Network (US-based)
Other
Albinism in animals