Red blood cell NADH diaphorase in Italian populations.

Abstract

NADH diaphorase is considered the most important enzyme which controls the level of methaemoglobin in the erythrocyte, thereby maintaining the pigment in the reduced functional state. Electrophorctic variants of this enzyme have been shown in subjects with methaemoglobinaemia (Kaplan and Beutler, 1967; West et al., 1967; Bloom and Zarkowsky, 1969). Studies on the frequency of such variants in healthy individuals were reported by Kaplan and Beutler (1967), Brewer et al. (1967), Defter et al. (1970) and tIopkinson et al. (1970). The last group carried out an extensive investigation on thousands of individuals : the overall frequency of variant phenotypes was about 1 °/o in European, Indian and Negro populations. In addition to the common phenotype Dia 1, Hopkinson et al. described 6 variant phenotypes: Dia 2 1 , 3--1, 4--1, 5--1, 6--1 and Dia 2. Family data support the hypothesis that the first 5 represent heterozygotes of one of a series of rare alleles (Dia 2, Dia ~, Dia 4, Dia 5 and Dia 6) with a common allele Oia 1 at an autosomal locus. The phenotype Dia 2 corresponds to the homozygote for Dia 2 allele. The present paper reports a study of red blood cell (RBC) NADH diaphorase in the Roman and Sardinian populations.