[Congenital methemoglobinemia: a rare case of cyanosis in the newborn].

We report the case of a newborn presenting a cyanosis after the birth with a good general state. Congenital methemoglobinemia is a rare disease which is characterized by a brutal appearance, in early infancy, of a bluish skin color not regressing with oxygen inspiration, and by a good general state. It is due to the recessive autosomal NADH-cytochrome b5 reductase (EC. 1.6.2.2) deficiency. This enzyme normally allows the reduction of the physiologically formed methemoglobinemia. Two forms of congenital methemoglobinemia have to be distinguished: the benign form (type I) and the severe form (type II).