Cohen syndrome
Encyclopedia
Cohen syndrome is believed to be a gene
mutation
at locus
8q22 gene COH1. Cohen syndrome has several characteristics such as obesity
, mental retardation
and craniofacial dysmorphism. It has an autosomal
recessive
transmission with variable expression.
Cohen syndrome is diagnosed by clinical examination, but often difficult due to variation in expression.
Ocular complications, though rare, are listed as optic atrophy, microphthalmia
, pigment
ary chorioretinitis
, hemeralopia
(decreased vision in bright light), myopia
, strabismus
, nystagmus and iris
/retina
l coloboma
.
General appearance is obesity with thin/elongated arms and legs. Micrognathia, short philtrum
, and high vaulted palate
are common. Variable mental retardation with occasional seizure
and deafness also is characteristic of Cohen syndrome. There is evidence to suggest a link between Cohen Syndrome and periodontal disease
.
One case of Cohen Syndrome, in a Palestinian boy from Tul-Karem, was reported in the Israeli monthly Kol Israel BeAsakim (in Hebrew) in the December 2007 issue.
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
mutation
Mutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
at locus
Locus (genetics)
In the fields of genetics and genetic computation, a locus is the specific location of a gene or DNA sequence on a chromosome. A variant of the DNA sequence at a given locus is called an allele. The ordered list of loci known for a particular genome is called a genetic map...
8q22 gene COH1. Cohen syndrome has several characteristics such as obesity
Obesity
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems...
, mental retardation
Mental retardation
Mental retardation is a generalized disorder appearing before adulthood, characterized by significantly impaired cognitive functioning and deficits in two or more adaptive behaviors...
and craniofacial dysmorphism. It has 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...
recessive
Recessive
In genetics, the term "recessive gene" refers to an allele that causes a phenotype that is only seen in a homozygous genotype and never in a heterozygous genotype. Every person has two copies of every gene on autosomal chromosomes, one from mother and one from father...
transmission with variable expression.
Cohen syndrome is diagnosed by clinical examination, but often difficult due to variation in expression.
Ocular complications, though rare, are listed as optic atrophy, microphthalmia
Microphthalmia
Microphthalmia also referred to as microphthalmos, nanophthalmia or nanophthalmos, is a developmental disorder of the eye that literally means small eye...
, pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
ary chorioretinitis
Chorioretinitis
Chorioretinitis is an inflammation of the choroid and retina of the eye. It is also known as choroid retinitis.-Causes:...
, hemeralopia
Hemeralopia
Hemeralopia is the inability to see clearly in bright light and is the exact opposite of Nyctalopia . Hemera was the Greek goddess of day and Nyx was the goddess of night. However, it has been used in an opposite sense by many non-English-speaking doctors...
(decreased vision in bright light), myopia
Myopia
Myopia , "shortsightedness" ) is a refractive defect of the eye in which collimated light produces image focus in front of the retina under conditions of accommodation. In simpler terms, myopia is a condition of the eye where the light that comes in does not directly focus on the retina but in...
, strabismus
Strabismus
Strabismus is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the extraocular muscles, which prevents bringing the gaze of each eye to the same point in space and preventing proper binocular vision, which may adversely...
, nystagmus and iris
Iris (anatomy)
The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus 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 , grey, violet, or even pink...
/retina
Retina
The 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...
l coloboma
Coloboma
A coloboma is a hole in one of the structures of the eye, such as the iris, retina, choroid or optic disc...
.
General appearance is obesity with thin/elongated arms and legs. Micrognathia, short philtrum
Philtrum
The philtrum , is a medial cleft common to many mammals, extending from the nose to the upper lip, and, together with a glandular rhinarium and slit-like nostrils, is believed to constitute the primitive condition for mammals in general...
, and high vaulted palate
Palate
The palate is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but, in most other tetrapods, the oral and nasal cavities are not truly separate. The palate is divided into two parts, the anterior...
are common. Variable mental retardation with occasional seizure
Seizure
An epileptic seizure, occasionally referred to as a fit, is defined as a transient symptom of "abnormal excessive or synchronous neuronal activity in the brain". The outward effect can be as dramatic as a wild thrashing movement or as mild as a brief loss of awareness...
and deafness also is characteristic of Cohen syndrome. There is evidence to suggest a link between Cohen Syndrome and periodontal disease
Periodontal disease
Periodontitis is a set of inflammatory diseases affecting the periodontium, i.e., the tissues that surround and support the teeth. Periodontitis involves progressive loss of the alveolar bone around the teeth, and if left untreated, can lead to the loosening and subsequent loss of teeth...
.
One case of Cohen Syndrome, in a Palestinian boy from Tul-Karem, was reported in the Israeli monthly Kol Israel BeAsakim (in Hebrew) in the December 2007 issue.