Microphthalmia and Anophthalmia, ALDH1A3 Associated
Patient Information
Characteristics
Background and History
Many gene changes (mutations) lead to abnormally small (microphthalmia) or missing eyeballs (anophthalmia). These may occur in association with malformations or disease in other parts of the body (syndromic) or they may occur by themselves (isolated).
Clinical Correlations
Patients are born with absence of one or both eyeballs or in other cases the eyes are abnormally small. In some patients malformations called cysts are found in the orbit where the eye is normally located. A few patients have heart or neurological disease.
Genetics
Inheritance
This condition results from changes in a specific gene known as ALDH1A3 and is inherited in an autosomal recessive pattern. Parents are usually related to each other (consanguineous marriages) and are clinically normal but carry the mutation in a single dose. When both parents transmit the changed gene to a child (which occurs with a 25% probability), the double dose of changes leads to this condition.
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
An ophthalmologist is usually the one to diagnose the full condition but the abnormal eyes may be evident to pediatricians at birth. The abnormally formed eye(s) often do not function properly and no treatment is available to restore vision. In other patients there may be some residual vision in which case low vision aids can be of help.
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