CORRELATION OF A MISSENSE MUTATION IN THE HUMAN SECRETOR ALPHA-1,2-FUCOSYL-TRANSFERASE GENE WITH THE LEWIS(A- A POTENTIAL MOLECULAR-BASIS FOR THE WEAK SECRETOR ALLELE (SE-W)(B+) PHENOTYPE )

A missense mutation (A(385) to T), predicting an Ile(129) to Phe subst itution, in the human Secretor alpha 1,2-fucosyltransferase gene was p resent in double dose in Lewis(a + b +) individuals, but not in Lewis( a - b +) individuals. Co-segregation of the Lewis(a + b +) phenotype w ith homozygosity for the mutation was also verified. These results yie ld a potential molecular basis for the weak Secretor allele (Se-w) acc ounting for the Lewis(a + b +) phenotype.