Table 1.

Causes of Congenital Methemoglobinemia

Autosomal Recessive	Autosomal Dominant
Cytochrome b5 reductase (CYB5R)deficiency (Congenital Methemoglobinemia)	Hemoglobin M disease
Subtypes: Congenital Methemoglobinemia Type I (enzyme defect in erythrocytes) Congenital Methemoglobinemia Type II (enzyme defect in all cells)	Subtypes: Boston Fort Ripley Hyde Park Iwate Kankakee Osaka Saskatoon