Purpose: We identified and examined four generations of a family with coexisting autosomal dominant zonular cataracts and sutural opacities and sought to determine their genetic basis.
Methods: Twenty-four of the 48 members in the family were examined. Systemic and ocular histories were obtained, and a detailed ophthalmic examination was performed. From each individual, 20 ml of blood was drawn for linkage studies with microsatellite markers in regions to which zonular cataracts had previously been localized (chromosomes 1, 2, and 16).
Results: Individuals of the first generation were reportedly asymptomatic. Several members of the second generation had morphologically identical zonular cataracts. Affected members of the third generation showed morphologic heterogeneity, with the zonular opacity varying from a uniform lamella to a segregation of dots. A high degree of consanguinity in the second generation suggested recessive inheritance with a pseudodominant inheritance pattern. However, examination of one member of the asymptomatic first generation disclosed senile cataractous changes superimposed on a faint zonular cataract enclosing sutural opacities and a pulverulent fetal nucleus. The latter findings were reconfirmed to be present in affected members of all generations, suggesting an autosomal dominant mode of inheritance. Initial efforts at linkage analysis excluded the gene locus causing this cataract from the Duffy, haptoglobin, and gamma-crystallin regions.
Conclusions: The cataract in this family is both phenotypically and genetically distinct from previously described and mapped cataracts.