Cataracts 46, Juvenile-Onset
Patient Information
Characteristics
Background and History
This type of hereditary juvenile cataract (lens opacities) has been reported in a genetic isolate of Lehrerleut Hutterites living in the northwestern United States and southwestern Canada. It is also found among the peoples of the Aland Islands, Finland. There is a high frequency of sudden death, presumably of cardiac origin, among young people with this type of cataract.
Clinical Correlations
Infants are born with clear lenses. Some opacification of the lenses is evident among children usually between the ages of 3 and 9 years. There may be considerable asymmetry in the degree of opacification but the progression is rapid and severe loss of vision occurs usually within three months after initial detection.
In the study populations numerous individuals with these cataracts experienced sudden death between the third and fifth decades of life presumably due to cardiac arrythmias. No other health problems have been reported.
Genetics
Inheritance
This type of juvenile cataract is inherited in an autosomal recessive pattern that requires both members of a specific gene to be changed. Thus if both parents carry such a mutation, each of their children inherit a 25% risk of developing 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
Infants are usually born with clear lenses and are otherwise healthy. The lenses become cloudy around 3 to 9 years of age and require cataract surgery within a few months following first detection. Cataract surgery (removal of the cloudy lens) takes place in one or more stages and is usually successful with good vision postoperatively.
The occurrence of sudden death at a young age presumably due to heart rhythm abnormalities suggests that affected individuals should have cardiac monitoring.
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