We analysed ABO genotype by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) at the four points of coding region (261, 526, 703 and 796 at cDNA). In 1990, Yamamoto et al, reported that nucleotide position 261 is the deletion site for 0 allelic cDNA and nucleotide position 526, 703 and 796 are the site where nucleotide substitutes take place between the coding regions of cDNA for A and B transferases.
We collected blood samples from 90 Japanese healthy adults consisted of 25 A-type, 23 B-type, 25 O-type, and 17 AB-type.
In 88 cases of 90, we could define the ABO genotype utilizing PCR-RFLP at the deletion position (nucleotide position 261) and at the nucleotide position 526 corresponding to the first amino acid substitution.
In the rest of 2 cases, A alleles showed the B allelic pattern at the nucleotide position corresponding both to the first and second amino acid substitution (nucleotide position 526 and 703, respectively).
But all A alleles showed the identical pattern at the nucleotide position 796 corresponding to the third amino acid substitution as Yamamoto et al. showed. A single base deletion was recognized in O allelic cDNA without exception so far.
These results suggest that it is necessary to test not only the first amino acid substitution but also the second and third amino acid subustitutions for the precise diagnosis of ABO genotype.
