Enzyme activity and distribution of adenosine deaminase types in a population of central Italy

Blood samples from 718 unrelated individuals born in municipalities of the 'Alto Maceratese' region in central Italy were examined for adenosine deaminase (ADA). The allele frequencies for ADA*1 and ADA*2 were 92.48 and 7.45%, respectively. One case of the rare ADA 5-1 phenotype was observed. The observed phenotype distribution agreed well with the one expected assuming a Hardy-Weinberg equilibrium. Enzyme activity was measured in red blood cells from individuals with different phenotypes. The relationships between the enzyme activity of the phenotypes was found to be ADA 1 greater than ADA 2-1 greater than ADA 2 greater than ADA 5-1.