ABSTRACT
The purpose of this study was to investigate the molecular genetic basis of A2 subgroup and identify the novel alleles at ABO locus in Chinese Han population. All seven exons and their flanking sequences, enhancer and promoter in the ABO gene of five samples from individuals with serological discrepancies were amplified by polymerase chain reaction (PCR); the PCR products were screened by directly sequencing; the haplotypes of exon 6 and 7 were analyzed by TOPO cloning sequencing. The results showed that five samples were identified as A2 or A2B subgroup by serological technology. The A201 and A205 alleles were confirmed in one A2B individual and one A2 individual, respectively. A novel A2 variant allele was identified in three A2B individuals. The two nucleotide acid alterations (467C > T and 539G > C) at the exon 7 resulting in two amino acid substitutions (P156L and R180P) in this novel allele were observed, when compared with A101 allele. It is concluded that the polymorphism of A2 allele is found to be relatively variable in Chinese population, and a novel A208 allele responsible for A2 subgroup is firstly reported.