ABO血型系统B101—002等位基因杂交导致的Bw亚型

Hybridization of B101 and 002 alleles responsible for Bw subgroup in ABO blood group

目的研究中国汉族个体红细胞ABO血型Bw亚型的分子遗传背景。方法通过标准血型血清学方法鉴定了1个家庭3例ABw亚型，PCR扩增样本基因组DNA的ABO基因增强子、启动子和外显子1～7及侧翼内含子序列，PCR产物经割胶纯化后直接测序，并将含有多态性位点的外显子7克隆到pcDNA3．1（-）质粒，转化DH5a后进行单倍体序列分析。结果3例ABw亚型的直接序列分析发现其ABO基因均有A102、B101和002等3种等位基因部分序列特征，但无法直接确定其基因型。单倍体序列分析表明，其中1个等位基因为A102，另1个为B101—002杂交等位基因，表现为B101等位基因基础上的646T〉A，657T〉C和681G〉A变异。在110份随机样本中未发现该杂交等位基因。结论B101和002等位基因杂交可能是导致该Bw亚型的分子机制。

Objective Bw subgroup of ABO blood group system was investigated to reveal its molecular genetic basis in Chinese HaM population. Methods The Abw subgroup of three relatives were identified by standard blood group serological techniques. The enhancer, promoter and exon 1 to exon 7 including flanking intron sequences of ABO gene were amplified by polymerase chain reaction. Direct sequencing was then performed on the gel-purified PCR products. Afterwards the exon 7 with polymorphic sites were cloned into pcDNA3.1 （ - ） vector and transformed into DH5α to carry out a haploid analysis. Results According to the direct sequencing analysis, sequence characteristics of the 3 tested subjects were found specific to partial sequence of A102, B101 and 002 alleles, thought the genotypes could not be confirmed directly. The haploid analysis affirmed that one allele is A102 while the other is a B101- 002 hybrid, which harbored 646T 〉 A, 657T 〉 C and 681G 〉 A variants compared with B101 allele. This hybrid allele was not detected in a 110 randomly selected samples. Conclusion The B101-O02 hybrid allele may account for the Bw phenotype and its molecular genetic basis.