[Blood genotyping of patients with ABO-group transformations in hematologic disorders]

Blood genotyping was performed in three patients with ABO-group transformation hematological disorders. Serological examinations revealed the following A-subtype transformations: case 1 was AML with A3B; case 2 was RAEB in transformation with A3; case 3 was AML with Alnt. Polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) analysis of the area flanking the two points 261 and 796 of the cDNA coding region revealed the genotypes of cases 1, 2 and 3 to be AB, AO, and AA, respectively. Four points in the cDNA coding region (467, 526, 703, and 871) were analyzed by PCR-RFLP to detect A-subtype-specific substitutions. Nucleotide position 467 is the substitution site for A-subtype allelic cDNA and 871 is the substitution site for the A3-subtype. At nucleotide positions 526 and 703, non-isosemantic substitutions are known to take place between the A1 and Aint alleles. No nucleotide substitutions specific to A-subtypes in this region were detected in any of the three cases. Thus, ABO blood group genotyping may be a useful way to distinguish between subtypes and transformations of phenotype.