Screening by allele-specific primer PCR (ASP-PCR) for these mutations among 100 Caucasian and 100 Black random blood donors indicated allele frequencies of 2 . 5% and 0%, respectively. Ala100Thr alone was present in 33% of the Caucasians (but none of the Blacks) with no weakening of FY expression.A novel allele at the FY locus associated with the Fy x phenotype was studied. Mistyping of this weak Fy b antigen in clinical transfusion medicine may lead to delayed haemolytic transfusion reactions in immunized patients. A potential role for genomic typing is proposed.

This simple and rapid polymerase chain reaction method was shown to detect the three common alleles at the FY locus in two representative ethnic populations. Its future use as an independent technique in red cell FY investigations and for fetal genotyping in hemolytic disease of the newborn is predicted.