Distribution of Adenosine Deaminase Types in Various Populations

Genetic variation of the enzyme, adenosine deaminase (ADA), can be detected by starch gel electrophoresis of human red cell lysates and an appropriate staining procedure (Spencer, Hopkinson, and Harris, 1968). Three phenotypes (ADA 1, ADA 2-1, and ADA 2) appear to be determined by two structural alleles, ADA' and ADA2. The frequency of the less common allele, ADA2, was reported to be 0 03 and 0 05 in London Negroes and Caucasians, respectively. Its frequency among Asiatic Indians was 0-12 (Hopkinson, Cook, and Harris, 1969). A very rare ADA 3-1 phenotype, found in an English family, has also been described (Hopkinson et al., 1969).