ObjectiveTo explore the blood group identification method of ABO subtype B(A) and its molecular mechanism.
MethodsIn July 2015, a patient who planned to conduct further blood group identification due to the inconsistent of ABO blood group positive and negative determination at the Taian Central Hospital in Shandong Province, was selected as the proband. This proband, her husband and 2 sons were selected as study subjects. This proband was female, and 45 years old. The ABO blood groups of all subjects were identified by serological methods. Sequence specific primer (SSP)-PCR was used to directly sequence the exon 6 and 7 of the subjects′, ABO gene, and their ABO genotypes were determined based on the sequencing results. The procedures followed in this study were in accordance with the standards established by the Medical Ethics Committee of Taian Central Hospital, and this study was approved by the committee (Approval No. 2015-018). All the subjects signed the informed consents for clinical trials.
Results① Results of ABO blood type positive and negative determination showed that the ABO blood groups of proband and her eldest son were B (A) subtype, and that of her husband and younger son were O type. Results of absorption and release test showed that A antigen was detected in the serum samples of the proband and her eldest son, but the A antigen was not detected in serum samples of her husband and the younger son. ② The gene sequencing results of the proband and her elder son indicated an O02allele and a nucleotide mutation at c. 640A>G in exon 7 of ABO gene, which was in accordance with the characteristic of B(A)04allele, and the genotype was B(A)04/O02. The genotype of proband′s husband and the younger son was O01/O02. The B(A)04allele of her elder son was come from his mother. The inheritance of B(A)04allele was cis.
ConclusionsThe method of molecular biology is necessary for identifying rare ABO subtypes. The c. 640A>G mutation on exon 7 of ABO gene is the genetic basis of B(A)04allele.
