High Frequency of Unusual ABO Alleles in Patients with Leukemia.

Background: Mutations critical for ABO group phenotypes which encode the catalytic domain of ABO glycosyltransferases have been studied in healthy blood donors. Weakening of A and B transferases have been reported in patients with leukemia, particularly those in which the myeloid lineage is involved. The purpose of this study was to use sequence specific PCR (PCR-SSP) to perform ABO genotyping of leukemic patients.

Material and Methods: A total of 108 unrelated leukemic patients were initially classified serologically using tube test technique and gel test for ABO typing and subgroup detection. Genomic DNA was prepared from peripheral blood cells. All samples were then screened by 32 different PCR-SSP, each specific for a single nucleotide variation to screen 16 known polymorfic sites of exons 6 and 7 (modified from Seltsam, Transfusion 2003,43(4):428–39.

Results: The results of PCR screening were conclusive and consistent with the ABO phenotypes in 71 patients (65.07%). Common ABO alleles were found in only 15 (13.8%) of patients studied. Unusual ABO alleles were found in 26 of 28 blood group O patients (ABO*O05, ABO*O21, ABO*O30, ABO*O33, ABO*O35, ABO*O36, ABO*O43 and ABO*O45), in 20 of 43 blood group A patients (ABO*A103, ABO*A104, ABO*A106, ABO*A202, ABO*A203), in 8 of 10 blood group B patients (ABO*B104, ABO*B105) and in 2 of 4 AB blood group patients (ABO*Bx01, ABO*B103). In 37 patients (34.2%), PCR screening revealed allele combinations that were incompatible with known ABO allele combinations or subgroups predicted by serologic analysis.

Conclusion: This is the first report of using PCR-SSP for ABO genotyping of leukemic patients. The pathophysiologic role of unusual ABO allele combinations in patients with leukemia warrants further investigation.