Abstract: ObjectiveTo analyze the characteristics of blood group serology and molecular mechanism of B3 subtype family members. MethodsBy using conventional blood serum method to identify blood type; detected the ABO preliminary genotyping by PCR-SSP method and amplified, sequenced and analyzed the nucleotide sequence of the sixth and seventh exon of ABO genes. ResultsTwo people in the family are A1B3 isoforms, containing anti-B antibody in serum. Three are B3 isoforms without anti-B antibody in serum. Genetic analysis reveals that the seventh exon has 1054C>T mutations, which causes the consequence that the polypeptide chain 352 nd arginine is replaced by tryptophan substitutions. ConclusionsThe point mutation of 1054C>T gene causes the molecular genetic basis of B3 subtypes, and can be stably inherited in the family. The techniques of molecular biology and human antiserum can identify the B3 subgroup correctly.

Key words: ABO, blood, group, system, B3, subtype, Genotype, Family