An analysis of polymorphism for the ABO blood group genes in a Japanese population based on polymerase chain reaction

The allele frequencies and the polymorphism in the ABO blood group gene of 340 individuals living in the central part of Japan near Tokyo were analyze d using polymerase chain reaction (PCR) based techniques. We analyzed the k nown polymorphic sites (at positions 297, 526, 657, 703, 796, 803 and 930) between A and B alleles, and the single deletion at position 261 in O allel es using PCR-RFLP (restriction fragment length polymorphism), PCR-SSCP (sin gle strand conformation polymorphism) and sequencing methods. We found two new allele subtypes in the A and B alleles. A new A allele subtype showed f our nucleotide differences at positions 297 (adenine versus guanine), 526 ( cytosine versus guanine), 657 (cytosine versus thymine) and 703 (guanine ve rsus adenine), and the allele frequency was 0.0044. This A allele subtype w as probably generated by a crossing-over of B allele and A or O allele. Sec ond new B allele subtype had a single nucleotide difference at position 467 (cytosine versus thymine) and the frequency was 0.0015. The ratio of a mut ant O allele (the nucleotide differences at positions 646, 681, 771 and 826 ) to the common O allele in the central part of Japan was low in the wester n part (Osaka region) and higher in the northern part (Yamagata region). Th ere may be a geographical dine for these two allele frequencies in Japan. T here was no difference in the transferase activities between common alleles and rare alleles.