A pedigree of congenital ptosis shows that 49 of 96 individuals were affected. Bilateral ptosis was present in 92% of those involved. There were five skip generations all mediated through the female lineage, a finding not reported with this frequency before in known pedigrees of congenital ptosis. A new classification of congenital ptosis is presented consisting of two subgroups, sporadic and genetic.
Cohen HB. Congenital PtosisA New Pedigree and Classification. Arch Ophthalmol. 1972;87(2):161-163. doi:10.1001/archopht.1972.01000020163008