Mental Retardation in Methemoglobinemia Due to Diaphorase Deficiency

Abstract
SEVERAL specific genetic lesions may result in congenital methemoglobinemia. Abnormal hemoglobins with mutations affecting alpha or beta globin near the site of heme attachment are found in most cases with a dominant mode of transmission.1 The biochemical defect in most cases of recessively inherited congenital methemoglobinemia is an almost complete deficiency of erythrocyte dihydronicotinamide adenine dinucleotide (NADH) or reduced diphosphopyridine nucleotide (DPNH), diaphorase activity.2 , 3 This enzyme functions with NADH as the principal agent reducing methemoglobin, which is constantly produced physiologically by the oxidation of hemoglobin. Gibson4 established the site of the metabolic defect and suggested that the reductase was a . . .