Histocompatibility antigens in two American Indian tribes of French Guiana.

Two South American Indian populations were typed for HLA antigens. In each, the individuals typed were related and their genealogies were known. Determination of their genotypes was done; there seemed to be neither excess nor deficiency in homozygotes. The antigens observed, A2, A9, Aw19.2 (Aw30-Aw31), A28 for the first locus and B5, Bw15, Bw35, Bw40 for the second locus are in accordance with those previously described for other South American Indians. The two populations belong to the same primary linguistic family Tupi-Guarani and they live in the same geographic area, but there was no intertribal marriage until recently. Genetic drift can explain the differences observed.