Microphthalmia, Syndromic 2
Patient Information
Characteristics
Background and History
This is one of several disorders in which the eyes are abnormally small. It differs from some others in that it occurs almost entirely in females and is associated with cataracts.
Clinical Correlations
Small, deep-set eyes and cataracts are present at birth. The lid openings are often small and the lids appear droopy. Some patients have glaucoma as well
The face is elongated and the nose is short with a broad tip. The primary teeth may erupt late and persist into at least adolescence. The number of teeth is often abnormal as well. The heart often has holes in the partitions and the valves may be abnormally floppy. A few patients have a cleft palate. Some patients have normal intelligence but others have psychomotor delays.
Genetics
Inheritance
This condition is caused by a mutation on the X chromosome which is apparently lethal in males and therefore the inheritance pattern is known as X-linked dominant. A few pedigrees with mother-daughter transmission have been reported.
Pedigree
X-linked dominant, mother affected
X-linked inheritance patterns result from mutations located on the X chromosome. Females have two X chromosomes of which only one carries a mutation in X-linked dominant disorders. This usually results in expression of the disease and women with a single mutation have the disorder caused by the mutation. Half of their offspring, male and female, will inherit the mutation. Men, with only one X chromosome, will always have the condition if they inherit the one with the mutation. Men would transmit it to all of their offspring. Without a modifying normal gene on a second X chromosome, X-linked dominant conditions are frequently lethal in such males. The result is a vertical transmission pattern, usually from female to female.
X-linked inheritance patterns result from mutations located on the X chromosome. Females have two X chromosomes of which only one carries a mutation in X-linked dominant disorders. This usually results in expression of the disease and women with a single mutation have the disorder caused by the mutation. Half of their offspring, male and female, will inherit the mutation. Men, with only one X chromosome, will always have the condition if they inherit the one with the mutation. Men would transmit it to all of their offspring. Without a modifying normal gene on a second X chromosome, X-linked dominant conditions are frequently lethal in such males. The result is a vertical transmission pattern, usually from female to female.
Diagnosis and Prognosis
The diagnosis requires collaboration between ophthalmologists, dentists and pediatricians. The prognosis is good in most patients. Cataracts can be surgically removed and glaucoma needs to be treated.
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