A Second Nonsecretor Allele of the Blood Group Α(1,2)Fucosyl-transferase Gene (FUT2)

Abstract

While screening Le(a+b+) Polynesian DN A samples for a candidate Se w allele, a point mutation (C 571 →T) resulting in a new stop codon (Arg 191 →stop) in the Α(1,2)fucosyltransferase gene (FUT2) was identified. This point mutation resulted in the gaining of a new restriction enzyme cleavage site ( DdeI ), which allowed restriction enzyme cleavage screening of 40 selected Polynesians and 42 random Caucasians. The nonsecretor phenotype in two of the three nonsecretor Polynesians analyzed was due to homozygosity for the ‘new’ mutation, whereas the third Polynesian nonsecretor (with Caucasian ancestors) was due to homozygosity of the ‘old’ (Trp 143 →stop) mutation. The nonsecretor phenotype in all Caucasians analyzed was a consequence of homozygosity for the ‘old’ mutation. Both the new and the old nonsecretor mutations were identified in the heterozygous state in some secretor-positive Polynesians, while only the old mutation was found in the heterozygous state in Caucasians of the same phenotype.