Cataracts, Congenital, Autosomal Recessive 3
Patient Information
Characteristics
Background and History
Opacities of the lens in the eye (cataracts) can result from a variety of causes such as infections, trauma, and various systemic diseases. Some like this one are inherited as the result of a mutation in a gene.
Clinical Correlations
This is a rare type of cataract that is present at birth. Nothing is known about the natural history and rate of progression, if any. It has only been reported in two families in Pakistan. In one family only cataracts were present and in the other the cornea (windshield of the eye) was small and there were scars present. In the latter family, individuals also had nystagmus (dancing of the eyes).
Genetics
Inheritance
The parents in each family were related but the families apparently not. This suggests autosomal recessive inheritance in which mutations in the two copies of the gene must be present for the cataracts to be expressed. Parents of these children can expect that each future child has a 25% chance of being born with cataracts. Nothing is known about the specific mutation causing these cataracts.
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
Ophthalmologists are usually the specialists that diagnose cataracts. If they interfere with vision, surgery for removal is required. No other disease is present.
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