Monozygotic twins with incompletely concordant simple congenital ptosis in a 4-generation pedigree.

This case reports 4-year-old monozygotic twins incompletely concordant for simple congenital ptosis. Pedigree analysis demonstrates 4 generations of autosomal dominant transmission. The case and pedigree are reviewed in light of a number of recent advances in the understanding of genetic influences on simple congenital ptosis.