Microphthalmia, Isolated, With Cataract 1

Clinical Features

Capella et al. (1963) reported a family in which 12 persons in 4 generations had microphthalmia and congenital cataract; 3 affected individuals also had mental retardation. No instance of male-to-male transmission was noted, but the ratio of affected to unaffected was 1:1, consistent with autosomal dominant transmission.

Zeiter (1963) described a family with bilateral microphthalmia, congenital cataract, and nystagmus in 7 members over 3 generations. Of the 4 affected family members in the youngest generation, 2 were mentally retarded and 1 of the latter also had congenital heart disease with presumed interventricular septal defect and patent ductus arteriosus as well as hydrocephalus and brain atrophy on ventriculogram.

Temtamy and Shalash (1974) reported a 3-year-old Egyptian boy, born of first-cousin parents, with bilateral microphthalmia, cataracts, and nystagmus. An older sister, who died at age 3 of a 'severe chest infection,' was said to have had an identical phenotype.

Cytogenetics

Yokoyama et al. (1992) described a family in which autosomal dominant congenital cataract and microphthalmia were segregating together with a reciprocal translocation t(2;16)(p22.3;p13.3) through 3 generations. There were several instances of male-to-male transmission of the ocular abnormality. The family included 4 persons with balanced translocations, 3 with partial trisomy 2p derived from the translocation, and 2 with a normal karyotype. All the subjects with balanced or unbalanced translocations had congenital cataract and microphthalmia, whereas the 2 persons with normal karyotypes did not show any ocular abnormalities. Molecular genetic studies demonstrated that the breakpoint in chromosome 16 was in the 16p13.3 region, proximal to HBA1 (141800). Yokoyama et al. (1992) concluded that a gene at the breakpoint on 16p was disrupted in the formation of the translocation.