20例ABO血型抗原表达异常样本的血型基因分析

Genetic analysis of weakened expression of ABO blood group antigen in 20 cases

目的探讨20例样本ABO血型抗原表达减弱的分子生物学机制。方法采用微柱凝集法及盐水试管法进行ABO血型血清学鉴定;对ABO基因第1-7外显子及其上游启动子区域PCR产物直接测序进行基因分型。结果11例样本通过家系分析可以确定其基因型(1例ABO*A2.01/ABO*B.01,1例ABO*A2.01/ABO*O01.01,1例A1.02/B3.04,2例B3.04/O.01.01、2例B3.02/O.01.02,4例Bw.12/O.01.01);3例样本在ABO基因启动子区域发生-35_-18位的碱基缺失,通过家系分析,提示该变异发生在B等位基因;1例样本在ABO基因启动子区域发生-119位C>T变异;1例样本发生第7外显子1054位点缺失碱基C;4例样本在ABO血型基因1-7外显子及其调控区域未发现变异。结论启动子区域-119位C>T变异及Exon71054del变异可能是导致ABO血型抗原异常表达的新变异;部分ABO亚型可能与内含子异常或mRNA合成异常有关;本地区B亚型明显多于A亚型。

Objective To explore the molecular mechanism for weakened expression of ABO blood group antigens in 20 cases.Methods Blood samples were collected from 20 cases with weakened expression of ABO blood group antigens,including 12 children undergoing elective surgery and 8 of their parents or grandparents.Serological identification of the ABO blood group was performed using microcolumn agglutination method and saline test tube method.The PCR products of exons 1-7 and their upstream promoter region of the ABO gene were directly sequenced for genotyping.Results In 11 of the cases,the ABO genotype could be determined by pedigree analysis(including 1 case of ABO*A2.01/ABO*B.01,1 case of ABO*A2.01/ABO*O01.01,1 case of A1.02/B3.04,2 cases of B3.04/O.01.01,2 cases of B3.02/O.01.02,and 4 cases of Bw.12/O.01.01).Pedigree analysis revealed deletion mutation at-35_-18 nt in the ABO promoter region in 3 cases,indicating that the mutation occurred in the B allele;a C>T mutation occurred at-119 nt in the ABO promoter region in 1 case;a C deletion at 1054 nt in exon 7 was identified in 1 case;no mutation was found in exons 1-7 and their regulatory region of ABO gene in 4 cases.Conclusion The C>T mutation at-119 nt in the promoter region and the deletion mutation at 1054 nt in exon 7 of ABO gene are probably new mutations leading to abnormal expression of ABO blood group antigens.Some ABO subtypes may be associated with abnormal introns or mRNAsynthesis.