中国人罕见的cisAB变异型分子机制分析

为研究中国人群ABO血型系统中罕见的cisAB变异型的分子遗传背景, 用血型血清学方法鉴定12例ABO血型疑难样本和116例随机无血缘关系样本, 应用聚合酶链反应和DNA序列分析等方法对样本ABO基因酶活性编码区外显子6、7和侧翼内含子进行突变筛选和检测, 并对不同基因型的扩增片段进行单倍体序列分析。血清学检测发现12个样本均为(A强B弱)或(A弱B强), PCR产物直接序列分析表明这些样本均为cisAB变异型, 并存在4种基因型。通过单倍体序列分析, 从中发现2种cisAB等位基因, 其中cisAB01不仅存在外显子7的467C>T和803G>C变异, 还在第6内含子存在未经报道的163T>C和179C>T变异; 另一种等位基因是在B101基础上保留了A101的803G位点, 编码一条176G、235S、266M和268G组合的多肽链。经检索, 未发现该组合的ABO等位基因, 该等位基因已被国际血型抗原基因突变数据库命名为cisAB05等位基因。文章系统研究了中国人群cisAB变异型分子机制, 发现了一种新的cisAB05等位基因, 同时根据内含子序列推测cisAB01等位基因可能是通过A101和B101等位基因间的同源交换而形成的。

Molecular genetic analysis of rare cisAB variants in Chinese population

We investigated the molecular genetic basis of rare cisAB variants at the ABO locus in Chinese population. Serological techniques were performed to characterize erythrocyte phenotype of 12 discrepant samples and 116 randomly selected samples. Mutations of complete exon 6 and 7 including flanking intron in the ABO genes were screened by PCR and directly sequencing. The haplotypes of diverse genotypes were also analyzed by cloning sequencing. Twelve samples were identified as AweakB or ABweak phenotype by serological technology, and were also identified as cisAB variants including four genotypes by directly sequencing. Two cisAB alleles were found by haplotype sequencing. One allele was cisAB01, in which four nucleotide acid alterations were observed (467C>T and 803G>C in exon 7, 163T>C and 179C>T in intron 6); the other allele maintained a nucleotide acid of A101 allele (803G) compared with B101 allele, which resulted in a polypep-tide containing 176G, 235S, 266M, and 268G four amino acids. This is a novel allele, which has been named cisAB05 by Blood Group Antigen Gene Mutation Database. According to systematically investigation of the molecular genetic basis of the cisAB variants in Chinese population, we found a novel cisAB05 allele and presumed that the cisAB01 allele is derived from homologues exchange of A101-B101 combination.