Cohen Syndrome
Patient Information
Characteristics
Background and History
Cohen syndrome was first reported by M. Michael Cohen, an American geneticist and oral and maxillofacial surgeon, and coworkers in 1973 . It occurs with high prevalence in Finnish populations.
Clinical Correlations
This is a disorder with manifestations throughout the body. Individuals are usually born with a normal head circumference but growth tends to lag behind with time. They may have a week high-pitched cry similar to a cat meow. The facial features are said to be characteristic with a low hairline, bushy eyebrows and eyelashes, and highly arched eyelids with a 'wavy' appearance. Delays in achieving milestones are evident in the first years of life, and mild to moderate mental retardation is common. A cheerful disposition is characteristic. Most patients have a low resistance to infections secondary to low white blood cell counts. Muscle tone is decreased so that arms and legs seem ‘floppy’ and joints are unusually flexible.
Many patients have visual problems in the first year of life and these become progressively worse. Night blindness and near sightedness are usually present but reduced vision secondary to a degeneration of the retina may lead to severe difficulties. There is also a progressive constriction of the peripheral field of vision which can cause individuals to appear clumsy by bumping into things.
Genetics
Inheritance
This is an autosomal recessive disorder that requires two copies of a mutation. One of these is inherited from each parent but the carrier parents do not have symptoms.
Pedigree
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
Diagnosis and Prognosis
Because of the characteristic features of this syndrome, a pediatrician or geneticist is usually able to make the diagnosis by clinical examination. Of course, a gene test is necessary to confirm the diagnosis since several other disorders can have some similar features.
Outside of the eye problems, this disorder is usually not progressive. Specifically, the mental deficits do not worsen and there is usually no serious disease of other internal organs.
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