A rare cause of cyanosis: Congenital methemoglobinemia.

Congenital Methemoglobinemia is a rare condition that may mimic congenital heart diseases. There are two types of congenital Methemoglobinemia. The type I is usually benign. The enzyme deficiency is limited to red blood cells. Clinically, the patient presents cyanosis without neurological disorders. Whereas, in type II, cyanosis is associated with severe neurological impairment.