A new genetic model proposing that the Se gene is a structural gene closely linked to the H gene

The Se gene is classically considered as a regulatory gene controlling the expression of the structural gene H in external secretions. Under this hypothesis, Bombay (h/h) individuals should not be able to express the Se gene. Statistical analysis of the 44 published Bombay pedigrees suggests on the contrary that there is no suppression of Se in Bombay individuals, and that both Se and H loci can be fully expressed at the phenotypic level. Based on a lod score of 12.9 at 1% recombination units and the existence of two different acceptors for the biosynthesis of the H antigen, a new genetic model is proposed in which H and Se would be two closely linked structural genes coding for two different 2-alpha-L-fucosyltransferases.