Ethnic variation in red cell glutathione peroxidase activity

Glutathione peroxidase activity was measured in blood and cultured fibroblasts from healthy persons of several different population groups. Individuals of Jewish ancestry and others of Mediterranean origin were found to manifest a decrease of red cell but not of leukocyte or fibroblast enzyme activity. Oriental populations differed in that the scatter in red cell enzyme activity was significantly lower than in Occidental populations. The erythrocyte enzyme of individuals with low activity was found to be less stable to heating than was the enzyme from persons with high activity. As a possible explanation for these data, a provisional genetic model is presented: a low GSH Px allele with a frequency of 0.556 in the Jewish population and of only 0.181 in the United States-Northern European population. Our results suggest that an association between GSH Px deficiency and hemolytic anemia need not represent a cause-and-effect relationship.