Cataracts, Congenital Zonular Pulverulent 3
Patient Information
Characteristics
Background and History
Opacification of the lens in the eye resulting in loss of transparency is called a cataract. Cataracts that appear in infants or childhood are generally called congenital or developmental cataracts. All newborns should have a complete eye examination since early detection and treatment can be important to prevent lazy eye (amblyopia). Cataracts may arise from a variety of causes including various general developmental syndromes, intrauterine infections such as rubella, chromosomal abnormalities, or inherited disorders of metabolism such as galactosemia. About one-fourth are familial and these are usually caused by single gene mutations. Inherited forms of cataracts are usually bilateral.
Clinical Correlations
Early onset cataracts that are inherited are often present to some degree at birth but may not be detected until later. These cataracts are often progressive as well so that serial monitoring is required and cataract surgery can be performed at an appropriate time. However, it is common for nearly everyone to have small, visually insignificant opacities in the lenses that do not progress and cause no difficulty in seeing. In other words, not all cataracts need to be removed.
Zonular cataracts consist of regional opacities in the lens within otherwise clear areas. In the disorder described here there are also tiny dot-like opacities located in the central or nuclear parts of the lens. They may be seen at birth or not until early childhood. They occur in both eyes and are progressive, often requiring surgery in adult life.
No other abnormalities are present.
Genetics
Inheritance
This type of cataract is inherited in an autosomal dominant pattern, i.e., parents with cataracts can expect that half their children will have similar lens opacities.
Pedigree
Autosomal dominant
Autosomal dominant disorders require only one mutation for the disease to be expressed. Since an affected parent has two chromosomes, only one of which has the mutant gene, parents can expect that half (50%) of their children will receive that one and inherit the disease. It is common for individuals that inherit the mutation, however, to not have evidence of the disease (nonpenetrance).
Autosomal dominant inheritance leads to a vertical pattern of transmission
Diagnosis and Prognosis
The outlook for vision and a healthy, normal lifespan is excellent. The diagnosis can only be made by an ophthalmologist who may suggest cataract surgery when vision is significantly impaired.
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