Document Type

Brief Communication


Adenosine deaminase {ADA, E.C. exhibits a wellknown polymorphism at the protein level. We have studied ADA and an STR polymorphism exhibiting variation of a TTTA repeat motif at intron 3 of the ADA gene in random samples from northern Portugal (N = 218) and southwestern Germany {N = 114). The ADA phenotype distribution and population data on the worldwide distribution of ADA favor recurrent mutation as an explanation for the maintenance of the ADA *2 gene product at polymorphic frequencies.