Single-tube multiplex PCR-SSCP analysis distinguishes 7 common ABO alleles and readily identifies new alleles

The ABO blood group is clinically the most important blood group system. Elucidation of the molecular basis of the ABO polymorphism allows genotype determination without family studies. Described here is a new method based on the simultaneous amplification by polymerase chain reaction (PCR) of 3 fragments from exon 6, and 5′ and 3′ ends of exon 7 of the ABO gene, followed by single-strand conformation polymorphism (SSCP) analysis. This multiplex PCR-SSCP protocol allows the well-established base changes at 9 nucleotide positions 261, 297, 467, 526, 646, 657, 681, 1059, and 1096 to be assayed simultaneously so that 7 common alleles (A1, A1v, A2, B, O1, O1v, and O2) can be distinguished in a single-tube single-lane format. Each allele was characterized by a set of 3 haplotype-specific SSCP patterns. Chinese (n = 125) and white European (n = 98) samples were analyzed, and their genotypes were found consistent with the serologic phenotypes or could be deduced unambiguously. Fifteen samples (2 Chinese and 13 white European) were each found carrying at least 1 rare allele. Most of these alleles were new and some might be generated by intragenic recombination. This technique is the simplest, quickest, and most informative method reported to date and also readily identifies new alleles.