Allele-related variations in the CCAAT-binding factor/NF-Y enhancer region of the A_2 blood group

Objective To identify the polymorphisms of CCAAT-binding factor/NF-Y enhancer region in individuals of Chinese Han population with A2 phenotype in ABO blood group system.Methods A total of 24 blood samples phenotyped as A2 subgroup and with known genotypes,detected from 2 940 randomly selected Chinese donors with A or AB blood group,were detected for nucleotide sequencing of the 5′regulatory region containing the CBF/NF-Y enhancer.Different sizes of PCR produce fragments obtained by gel purification Kit led to direct sequence.Results Seven samples with the A201 allele had four 43-bp microsatellite repeats while the A205 allele had single 43-bp repeat within the CBF/NF-Y enhancer region of ABO gene.A nucleotide substitution(GA)at nt.41 of the only one repeat in 15 individuals with the A205 allele were detected.No special molecular background was found in the two samples which were phenotyped as A2,but genotyped as A102/B101.Conclusion CBF/NF-Y enhancer region of the A2 alleles occurs with minisatellite fragments length polymorphisms.Allele-specific variations in CBF/NF-Y enhancer region of A2 blood group gene were elucidated in Chinese population.