Nictitating membrane in trisomy 18 syndrome.

A 2,290-g infant boy born after a 43-week gestation had the classic, somatic, and dermatoglyphic findings of trisomy 18 (Edwards) syndrome. The diagnosis was established cytogenetically. A bilateral nictitating membrane was present. In contrast to those in lower species this membrane was established horizontally and moved cephalad for closure. Thus, the membrane occasionally coverd the conjunctiva and cornea completely, giving the impression of corneal clouding. Postmortem studies were not permitted.