α1,3半乳糖基转移酶基因721C>T突变导致B_w亚型

C721T mutation of the α1,3 galactosyltransferase gene responsible for B_w subgroup

目的 研究红细胞ABO血型系统Bw亚型的分子基础。方法 通过标准血型血清学方法明确鉴定2个家庭3例Bw亚型,PCR扩增Bw 亚型ABO糖基转移酶基因的增强子、启动子和第1～7外显子及侧翼内含子序列,PCR产物经割胶纯化后直接测序。同时将第6和7外显子克隆到pc DNA3.1(- )质粒,转化DH5α后进行序列分析。采用序列特异性引物-聚合酶链反应方法证实测序所发现的突变。结果 直接测序发现3例Bw亚型的基因型为B/ O杂合,其中糖基转移酶基因的第2 6 1位G杂合缺失,第72 1位C/ T杂合。克隆证实一条染色体上为正常的O等位基因,另一条染色体上B等位基因(α1,3半乳糖基转移酶基因)存在第72 1位C>T突变,导致多肽链Arg2 4 1Trp替换。序列特异性引物-聚合酶链反应检测14 0份随机样本未发现此突变。结论 α1,3半乳糖基转移酶基因第7外显子72 1C>T突变可能是Bw亚型分子遗传基础之一。

Objective To gain an insight into the molecular genetic basis of B w subgroup of ABO blood group system. Methods Three B w phenotypes were confirmed by standard serological techniques. The enhancer, promoter and exons 1-7 including flanking introns of ABO gene were amplified and directly sequenced after PCR amplified fragments being purified by gel. Exons 6 and 7 were also sequenced after pcDNA3.1(-) vector transformation. The sequence specific primer-polymerase chain reaction was performed to confirm the mutations detected by sequencing in this study. Results Genotypes of three individuals were B w/O by direct sequencing, there were G deletion heterozygous at position 261 and C/T heterozygous at position 721. A normal O allele was confirmed by cloning sequencing and 721 C>T mutation of the α1,3 galactosyltransferase(B allele) gene was also observed, which caused amino acid 241 Arg>Trp substitution. This mutation was not detected in 140 random samples by PCR-SSP. Conclusion The mutation of 721C>T in the α1,3 galactosyltransferase gene may be one of the molecular genetic bases of B w phenotype.