Ophthalmic manifestations of neonatal protein C deficiency.

Protein C is a vitamin K dependent plasma zymogen which acts by regulating coagulation by its specific inactivation of factors V and VII, and facilitates fibrinolysis by elevating circulating plasminogen activator levels. Protein C deficiency is a rare condition which predisposes to episodes ofpotentially blinding and lethal thromboembolism. In the newborn period, congenital protein C deficiency occurs as an autosomal recessively inherited condition; homozygotes have very low or undetectable protein C activity (usually'less than 1%, normal 70-140%)' and present within the first few days of life. Heterozygotes have levels of around 50% and usually remain asymptomatic until adolescence or adult life. Neonatal protein C deficiency may also be acquired and transient, occurring particularly in ill preterm babies2 with the resultant thromboses being as profound as in the homozygous state. We present two cases of neonatal protein C deficiency, one with the classic homozygous state and the other a premature neonate with a probable acquired state. Both cases developed the typical systemic manifestation of purpura fulminans (necrotic skin lesions).