Advances in the Genetics of Congenital Ptosis.

Congenital ptosis, a birth defects presents at birth or by 1 year of age, is characterized by the drooping of the upper eyelid. Either in isolation (nonsyndromic) or with many different systemic disorders (syndromic). The estimated prevalence of ptosis (congenital and acquired) ranges from 0.79 to 1.99 per 10,000 people in different populations, and it is more prevalent in males. The underlying pathogenesis of congenital ptosis is myogenic and neurogenic, related to the development of muscles and nerves. Although most cases are sporadic, there are familial transmission characteristics, including autosomal dominant, recessive mode, and X-linkage inheritance patterns. Moreover, some forms are due to chromosomal aberrations and mutations and deletions in mitochondrial DNA. Genes involved in simple congenital ptosis (SCP) are ZFHX4 and COL25A1. The clinical aspects of various syndromes involving congenital ptosis are partly caused by single-gene mutations. However, the pathogenesis of congenital ptosis is not fully understood. We review the reported epidemiology, genetics, and clinical features of congenital ptosis and associated syndromes here.