Congenital disorder

Congenital disorder

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A congenital disorder, or congenital disease, is a condition existing at birth
Birth
Birth is the act or process of bearing or bringing forth offspring. The offspring is brought forth from the mother. The time of human birth is defined as the time at which the fetus comes out of the mother's womb into the world...

 and often before birth, or that develops during the first month of life (neonatal disease), regardless of causation. Of these diseases, those characterized by structural deformities are termed "congenital anomalies"; that is a different concept (MeSH) which involves defects in or damage to a developing fetus
Fetus
A fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth.In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.-Etymology and spelling variations:The...

.

A congenital disorder may be the result of genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....

 abnormalities, the intrauterine (uterus
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...

) environment, errors of morphogenesis
Morphogenesis
Morphogenesis , is the biological process that causes an organism to develop its shape...

, infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

, or a chromosomal abnormality. The outcome of the disorder will depend on complex interactions between the pre-natal deficit and the post-natal
Postnatal
Postnatal is the period beginning immediately after the birth of a child and extending for about six weeks. Another term would be postpartum period, as it refers to the mother...

 environment. Animal studies indicate that the mother's (and possibly the father's) diet, vitamin
Vitamin
A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. In other words, an organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on...

 intake, and glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

 levels prior to ovulation
Ovulation
Ovulation is the process in a female's menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum . Ovulation also occurs in the estrous cycle of other female mammals, which differs in many fundamental ways from the menstrual cycle...

 and conception have long-term effects on fetal growth and adolescent and adult disease. Congenital disorders vary widely in causation and abnormalities. Any substance that causes birth defects is known as a teratogen.

The older term congenital disorder does not necessarily refer to a genetic disorder
Genetic disorder
A genetic disorder is an illness caused by abnormalities in genes or chromosomes, especially a condition that is present from before birth. Most genetic disorders are quite rare and affect one person in every several thousands or millions....

 despite the similarity of the words. Some disorders can be detected before birth through prenatal diagnosis
Prenatal diagnosis
Prenatal diagnosis or prenatal screening is testing for diseases or conditions in a fetus or embryo before it is born. The aim is to detect birth defects such as neural tube defects, Down syndrome, chromosome abnormalities, genetic diseases and other conditions, such as spina bifida, cleft palate,...

 (screening).

Classification


Much of the language used for describing congenital conditions predates genomic mapping, and structural conditions are often considered separately from other congenital conditions. It is now known that many metabolic conditions may have subtle structural expression, and structural conditions often have genetic links. Still, congenital conditions are often classified in a structural basis, organized when possible by primary organ system affected.

Primarily structural



Several terms are used to describe congenital abnormalities. (Some of these are also used to describe noncongenital conditions, and more than one term may apply in an individual condition.)
  • A congenital physical anomaly is an abnormality of the structure of a body part. An anomaly may or may not be perceived as a problem condition. Many, if not most, people have one or more minor physical anomalies
    Minor physical anomalies
    Minor physical anomalies are relatively minor congenital physical abnormalities consisting of features such as low-seated ears, single transverse palmar crease, telecanthus, micrognathism a furrowed tongue...

     if examined carefully. Examples of minor anomalies can include curvature of the 5th finger (clinodactyly
    Clinodactyly
    -References:...

    ), a third nipple, tiny indentations of the skin near the ears (preauricular pits), shortness of the 4th metacarpal or metatarsal bones, or dimples over the lower spine (sacral dimple
    Sacral dimple
    A sacral dimple or pilonidal dimple is a small hole located just above the buttocks. The name comes from the sacrum, the bone at the end of the spine, over which the dimples are found. More than 2% of babies may have such dimples; almost all of these are very minor...

    s). Some minor anomalies may be clues to more significant internal abnormalities.
  • Birth defect is a widely used term for a congenital malformation, i.e. a congenital, physical anomaly which is recognizable at birth
    Birth
    Birth is the act or process of bearing or bringing forth offspring. The offspring is brought forth from the mother. The time of human birth is defined as the time at which the fetus comes out of the mother's womb into the world...

    , and which is significant enough to be considered a problem. According to the CDC
    Centers for Disease Control and Prevention
    The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...

    , most birth defects are believed to be caused by a complex mix of factors including genetics, environment, and behaviors, though many birth defects have no known cause. An example of a birth defect is cleft palate.
  • A congenital malformation is a congenital physical anomaly that is deleterious, i.e. a structural defect perceived as a problem. A typical combination of malformations affecting more than one body part is referred to as a malformation syndrome.
  • Some conditions are due to abnormal tissue development:
    • A malformation is associated with a disorder of tissue development. Malformations often occur in the first trimester.
    • A dysplasia
      Dysplasia
      Dysplasia , is a term used in pathology to refer to an abnormality of development. This generally consists of an expansion of immature cells, with a corresponding decrease in the number and location of mature cells. Dysplasia is often indicative of an early neoplastic process...

      is a disorder at the organ level that is due to problems with tissue development.
  • It is also possible for conditions to arise after tissue is formed:
    • A deformation
      Deformity
      A deformity, dysmorphism, or dysmorphic feature is a major difference in the shape of body part or organ compared to the average shape of that part.Deformity may arise from numerous causes:*A Genetic mutation*Damage to the fetus or uterus...

      is a condition arising from mechanical stress to normal tissue. Deformations often occur in the second or third semester, and can be due to oligohydramnios
      Oligohydramnios
      Oligohydramnios is a condition in pregnancy characterized by a deficiency of amniotic fluid. It is the opposite of polyhydramnios.-Diagnosis:Diagnosis is made by ultrasound measurement of the amniotic fluid index...

      .
  • A disruption involves breakdown of normal tissues.
  • When multiple effects occur in a specified order, it is known as a sequence
    Sequence (medicine)
    In medicine, a sequence is a series of ordered consequences due to a single cause.It differs from a syndrome in that seriality is more predictable: if A causes B, and B causes C, and C causes D, then D would not be seen if C is not seen...

    . When the order is not known, it is a syndrome
    Syndrome
    In medicine and psychology, a syndrome is the association of several clinically recognizable features, signs , symptoms , phenomena or characteristics that often occur together, so that the presence of one or more features alerts the physician to the possible presence of the others...

    .

Other

  • Genetic disorder
    Genetic disorder
    A genetic disorder is an illness caused by abnormalities in genes or chromosomes, especially a condition that is present from before birth. Most genetic disorders are quite rare and affect one person in every several thousands or millions....

    s
    or diseases are all congenital, though they may not be expressed or recognized until later in life. Genetic diseases may be divided into single-gene defects, multiple-gene disorders, or chromosomal defects. Single-gene defects may arise from abnormalities of both copies of an autosomal
    Autosome
    An autosome is a chromosome that is not a sex chromosome, or allosome; that is to say, there is an equal number of copies of the chromosome in males and females. For example, in humans, there are 22 pairs of autosomes. In addition to autosomes, there are sex chromosomes, to be specific: X and Y...

     gene (a recessive disorder) or of only one of the two copies (a dominant disorder). Some conditions result from deletions or abnormalities of a few genes located contiguously on a chromosome. Chromosomal disorders involve the loss or duplication of larger portions of a chromosome (or an entire chromosome) containing hundreds of genes. Large chromosomal abnormalities always produce effects on many different body parts and organ systems.
  • A congenital metabolic disease is also referred to as an inborn error of metabolism
    Inborn error of metabolism
    Inborn errors of metabolism comprise a large class of genetic diseases involving disorders of metabolism. The majority are due to defects of single genes that code for enzymes that facilitate conversion of various substances into others...

    . Most of these are single gene defects, usually heritable. Many affect the structure of body parts but some simply affect the function.
  • Other well defined genetic conditions may affect the production of hormones, receptors, structural proteins, and ion channels.

Antibiotics


Use of antibiotics around the time of conception
Fertilisation
Fertilisation is the fusion of gametes to produce a new organism. In animals, the process involves the fusion of an ovum with a sperm, which eventually leads to the development of an embryo...

, particularly sulfonamides and nitrofurantoin
Nitrofurantoin
Nitrofurantoin is an antibiotic which is marketed under the following brand names; Furadantin, Macrobid, Macrodantin, Nitrofur Mac, Nitro Macro, Nifty-SR, Martifur-MR, Martifur-100 , Urantoin, and Uvamin . It is usually used in treating urinary tract infection...

 are associated with major birth defects. Whether or not this association is causal has not been determined.

Epidemiology


Cell division errors can be due to a lack of nutrients or availability of atomic building blocks, or the presence of toxins that impede normal growth. Division errors which occur very early in the development of a multicellular organism can result in large scale structural and functional differences in the organism's final shape. For example it is now understood that a lack of folic acid
Folic acid
Folic acid and folate , as well as pteroyl-L-glutamic acid, pteroyl-L-glutamate, and pteroylmonoglutamic acid are forms of the water-soluble vitamin B9...

 in the diet of a mother can cause cellular neural tube
Neural tube
In the developing vertebrate, the neural tube is the embryo's precursor to the central nervous system, which comprises the brain and spinal cord...

 deformities that result in Spina Bifida
Spina bifida
Spina bifida is a developmental congenital disorder caused by the incomplete closing of the embryonic neural tube. Some vertebrae overlying the spinal cord are not fully formed and remain unfused and open. If the opening is large enough, this allows a portion of the spinal cord to protrude through...

.

External physical shocks or constrainment due to growth in a restricted space, may result in unintended deformation or separation of cellular structures resulting in an abnormal final shape or damaged structures unable to function as expected.

For multicellular organisms that develop in a womb, the physical interference or presence of other similarly developing organisms such as twins
TWINS
Two Wide-Angle Imaging Neutral-Atom Spectrometers are a pair of NASA instruments aboard two United States National Reconnaissance Office satellites in Molniya orbits. TWINS was designed to provide stereo images of the Earth's ring current. The first instrument, TWINS-1, was launched aboard USA-184...

 can result in the two cellular masses being integrated into a larger whole, with the combined cells attempting to continue to develop in a matter that satisfies the intended growth patterns of both cell masses. The two cellular masses can compete with each other, and may either duplicate or merge various structures. This results in conditions such as conjoined twins
Conjoined twins
Conjoined twins are identical twins whose bodies are joined in utero. A rare phenomenon, the occurrence is estimated to range from 1 in 50,000 births to 1 in 100,000 births, with a somewhat higher incidence in Southwest Asia and Africa. Approximately half are stillborn, and a smaller fraction of...

, and the resulting merged organism may die at birth when it must leave the life-sustaining environment of the womb and must attempt to sustain its biological processes independently.

Fossil record



Evidence for congenital deformities found in the fossil record is studied by paleopathologists, specialists in ancient disease and injury. Fossils bearing evidence of congenital deformity are scientifically significant because they can help scientists infer the evolutionary history of life's developmental processes. For instance, because a Tyrannosaurus rex specimen has been discovered with a block vertebra, it means that vertebrae have been developing the same basic way since at least the most recent common ancestor of dinosaurs and mammals. Other notable fossil deformities include a hatchling specimen of the bird-like dinosaur, Troodon
Troodon
Troodon is a genus of relatively small, bird-like dinosaur from the Late Cretaceous period . Discovered in 1855, it was among the first dinosaurs found in North America...

, the tip of whose jaw was twisted. Another notably deformed fossil was a specimen of the choristodere Hyphalosaurus
Hyphalosaurus
Hyphalosaurus is a genus of freshwater aquatic reptile, and a major part of the Jehol Biota. It lived during the early Cretaceous period , about 122 million years ago. It contains two species, H. lingyuanensis and H. baitaigouensis, both from the Yixian Formation of Liaoning Province, China...

, which had two heads- the oldest known example of polycephaly
Polycephaly
Polycephaly is a condition of having more than one head. The term is derived from the Greek stems poly- meaning 'much' and kephali- meaning "head", and encompasses bicephaly and dicephaly . A variation is an animal born with two faces on a single head, a condition known as diprosopus...

.

See also

  • Congenital abnormality
    Congenital abnormality
    A congenital anomaly is a condition which is present at the time of birth which varies from the standard presentation....

  • Malformative syndrome
    Malformative syndrome
    A malformative syndrome is a recognizable pattern of congenital anomalies that are known or thought to be causally related .- Causes :* exogenous causes...

  • ICD-10 Chapter Q: Congenital malformations, deformations and chromosomal abnormalities
  • List of congenital disorders
  • List of ICD-9 codes 740-759: Congenital anomalies
  • March of Dimes
    March of Dimes
    The March of Dimes Foundation is a United States nonprofit organization that works to improve the health of mothers and babies.-Organization:...

  • Mitochondrial disease
    Mitochondrial disease
    Mitochondrial diseases are a group of disorders caused by dysfunctional mitochondria, the organelles that are the "powerhouses" of the cell. Mitochondria are found in every cell of the human body except red blood cells...


External links