Absence of the Diego antigen, a genetic characteristic of early immigrants to South America.

The Diego blood group is an exclusive Mongoloid gene marker, although it is not present in all Mongoloid populations. The absence of the gene in Waica Indians and its very low frequencies in Warrau and Yaruro Indians of South America suggest that it represents a genetic characteristic of Marginal American Indians. Since Marginal Indians are considered to be early comers to the New World, we suggest that Diego-negative populations were the first to arrive and to extend throughout South America, while the Diego-positive tribes came later.