Variable expressivity of autosomal dominant anterior segment mesenchymal dysgenesis in six generations.

Of 58 members in a six-generation family with anterior segment mesenchymal dysgenesis with variable expressivity, 21 of 35 members (60%) at risk were affected. Of the 15 living affected family members, nine (60%) had visual acuities of 6/12 (20/40) or better in at least one eye, five (33%) had visual acuities between 6/15 and 6/60 (20/50 and 20/200) in at least one eye, and one (7%) had a visual acuity of less than counting fingers at one foot in both eyes. All nine affected patients who underwent slit-lamp examinations had corneal abnormalities with and without synechiae. All 15 affected patients also had cataracts, and three of the 15 (20%) had optic nerve abnormalities. In a corneal button from the severely affected proband, Descemet's layer and endothelial cells were absent even in the periphery. Other corneal and lenticular changes were secondary to the primary endothelial defect. Anterior segment mesenchymal dysgenesis in this family appeared to be caused by an aberration of the first wave of mesenchyme from the rim of the optic cup.