Methemoglobin Reductase Deficiency

Clinical Features

Sass et al. (1967) found a black male with deficiency of NADPH (TPNH)-methemoglobin reductase, also known as NADPH-reductase and biliverdin reductase B (BLVRB; 600941). The case was detected when the patient's red cells were found to be abnormal with the methylene-blue screening test, which is ordinarily an indication of G6PD deficiency; by actual assay, G6PD activity was normal. Administration of primaquine for 30 days produced no hemolysis. Five close relatives including the mother had intermediate levels of NADPH-methemoglobin reductase consistent with heterozygous status. The father was dead. As one would predict from knowledge of the relative activities of the NADPH- and NADH (DPNH)-methemoglobin reductases, methemoglobinemia was not present in the presumed homozygote.

Bloom and Zarkowsky (1970) also reported such a patient. Their patient, in comparison with methemoglobinemia cases, demonstrated that NADPH-reductase is separate from NADH-reductase.