Hereditary Methemoglobinemia due to NADH Cytochrome b₅ Abnormality

—Clinical Importance of the Enzyme in Leukocytes and Platelets—

Abstract

NADH cytochrome b₅ reductase in erythrocytes, granulocytes, lymphocytes and platelets was investigated in two siblings with hereditary methemoglobinemia and in their parents.
NADH cytochrome b₅ reductase levels were markedly low in the erythrocytes derived from the propositus and her brother. Based on the findings that the NADH cytochrome b₅ reductase abnormality was limited to thye erthrocytes (erythrocyte type), it was suspected that the mental development of these patients should be normal. A follow-up study on their mental development was carried out in order to confirm whether or not this was true. At present, the propositus, who is 2 years and 11 monts old, and her brother, who is 3 years and 10 months old, have developed without any signs of mental retardation.
These findings indicate that the determination of the type of NADH cytochrome b₅ reductase abnormality (erythrocyte type or generalized type) might be useful in anticipating the complication of mental retardation in hereditary methemoglobinemia.