中国汉族人群检出新的B(A)641T>C等位基因

目的明确稀有ABO表现型的遗传学基础。方法对ABO血清学常规定型正反不一致的样本,采用PCR-RFLP方法作初步基因分型,对8例血清学表现为AwB,而基因分型具有O基因的个体,进行ABO基因第6和7外显子PCR产物的TA克隆及核苷酸序列测定。结果8例样本除1对为母女关系外,其余无任何亲缘关系,血清学表现相似,红细胞上含有接近正常的B抗原和少量A抗原,H抗原含量较正常B细胞显著增高,血清中存在抗-A,初定为AwB,基因分型均为BO。克隆测序表明除具有正常O1或者O1V基因外,他们的B基因第7外显子在正常B等位基因的基础上,均发生单碱基突变,4例发生nt700C>G点突变,导致Pro234Ala,2例无关个体为nt640A>G点突变,导致Met214Val,1对母女均表现nt641T>C点突变,导致Met214Thr。证实所有8例样本真正血型应为B(A)表现型,其基因型均为B(A)/O型。结论在中国汉族人群中检出3种B(A)血型,除了已在我国台湾首先被发现的B(A)700C>G和笔者以前报道的B(A)640A>G之外,新发现1种B(A)641T>C等位基因。

Study on B(A) phenotypes and identification of novel B(A)641 allele in chinese population

Objective To determine the genetic basis of 8 ABO blood group samples which showed conflicting results for blood grouping and genotyping. Methods An absorption-elution test and family study were conducted to study ABO subgroups involved in ABO grouping discrepancies. PCR-SSP and PCR-RFLP methods were used for ABO genotyping. PCR products of exon 6 and 7 were cloned and sequenced. Results All of these samples were suspected to be the A_ weak B phenotype by blood group serological test and to have a BO genotype by primary genotyping. Results of the sequencing analysis indicated that four out of the 8 samples had the nt700C>G mutation in the B gene, which were previously defined as B(A)700. Among the remaining 4, 2 unrelated individuals had the same novel 640A>G mutation as we reported before, while the other 2 individuals who were mother and daughter had a 641T>C mutation. All 8 samples displayed the B(A) phenotype. Their real genotypes were B(A)/O. Conclusion Three B(A) alleles in the Chinese Han population were detected. Two alleles,B(A)700,B(A)640 were reported previously. One novel allele B(A)641, was first identified in this study.