A familial case of ABO phenotype-genotype discrepancy.

In the present study, we detected a familial case of ABO phenotype-genotype discrepancy. Although the observed phenotypes were B and O, the corresponding ABO genotypes were AB and AOG, respectively, by routine examination. Exons 6 and 7 of the ABO gene were sequenced and subsequently, the sequence of the allele responsible for ABO phenotype-genotype discrepancy was examined. Our results indicated that the Ax allele was present in 3 family members. By employing traditional serological methods, we further identified and confirmed that the allele Ax and the resulting Ax phenotype are responsible for ABO phenotype-genotype discrepancy.