Sequence analysis of exon 6/7 and flanking intron of cisAB subgroup

Objective To investigate the molecular genetic basis cisAB subgroup of ABO blood group system in Han nationality.Method On basis of standard serological identification for blood group and genotyping by PCR SSP, genomicDNA sequences of complete exon 6 and 7 including flanking intron of cisAB subgroup in 2 individuals of Han nationality were amplified by specific primers. The PCR products were directly sequenced following gel purification by Bigdye Sequencing kit.Results The 2 individuals (propositus and her father) were blood grouped serologically as A2B3 and A3B respectively, and the propositus was genotyped as BO 1 by the PCR SSP assay.According to the sequence analysis, three heterozygous alleles in the propositus were observed:261G (deletion and non deletion) in exon6,T467C in exon 7,and the C803G in exon 7 while a normal C at locus 796 compared with A1 allele,thus the 2 samples were defined as unusual cisAB subgroup.Conclusion The unique mutations of T467C, C803G and normal 796C explain the molecular genetic basis of cisAB phenotype.