Quantitative variations in polymorphic types of human red cell esterase D.

Human red cell esterase D was analysed quantitatively in Japanese samples. Among the three esterase D phenotypes there was a significant difference in catalytic activity, with an approximate ratio of 7:5:3 for EsD 1, EsD 2-1 and EsD 2. With a few inter-type individuals, the distribution of their activity values was plotted in a tri-modal curve. These results suggest that the esterase D system in human red cells is qualitatively and even quantitatively controlled by genes.