Variant of type B blood in an El Salvador family. Expression of a variant B gene enhanced by the presence of an A2 gene.

A variant of type B blood was found in three members of a family from El Salvador. In two members, both genotype BO, the blood and saliva had the characteristics of the phenotype Be1 . In the third member, genotype A2B, the red cell B antigen was stronger than in his BO genotype relatives. Thus, in this family, the presence of the A2 gene appeared to enhance the expression of the B gene.