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本研究探讨2例ABO亚型A2B的分子机制。利用单克隆抗体检测先证者红细胞ABO血型抗原,用标准A、B、O细胞检测先证者血清中的ABO抗体,采用聚合酶链反应(polymerase chain reaction,PCR)技术扩增先证者ABO基因的第5至7外显子序列,其PCR产物经酶切后直接测序分析。同时,PCR产物经TOPO TA克隆到质粒载体中获得单链,对所得克隆进行ABO基因第6、7外显子双向测序分析。结果表明,先证者红细胞有A、B抗原,同时其血清中存在抗A1抗体。直接测序分析发现,第261位无缺失,第297位A/G、467C/T、526C/G、657C/T、703G/A、742C/T、796C/A、803G/C、930G/A杂合。克隆测序得到B101和1个新的A等位基因。与A102相比,新A等位基因仅在第742位C→T突变,导致第248位精氨酸变成色氨酸,新等位基因已被正式命名为A213。结论 :α-1,3-N-乙酰半乳糖胺基转移酶基因第742位C→T突变导致产生A2表型,表型个体血清中可含有抗A1抗体。
This study explored the molecular mechanism of two ABO subtypes A2B. The monoclonal antibody was used to detect the ABO blood group antigens of the probands. The ABO antibodies in the probands were detected by standard A, B and O cells. The proband ABO was amplified by polymerase chain reaction (PCR) Genes 5 to 7 exon sequences, the PCR products were digested by direct sequencing analysis. Meanwhile, the PCR product was cloned into the plasmid vector by TOPO TA to obtain a single strand, and the obtained clones were subjected to the exon 6 and 7 exon bi-directional sequencing analysis of the ABO gene. The results show that proband erythrocytes have A, B antigen, while the presence of anti-A1 antibodies in serum. The direct sequencing analysis showed that there was no deletion at position 261, the 297th A / G, 467C / T, 526C / G, 657C / T, 703G / A, 742C / T, 796C / A, 803G / C, 930G / A Together Cloning and sequencing gave B101 and a new A allele. Compared to A102, the new A allele was mutated only at the 742th C → T mutation, resulting in the conversion of 248th arginine to tryptophan and the new allele as A213. CONCLUSION: The C → T mutation at position 742 of α-1,3-N-acetylgalactosaminyltransferase gene results in the production of A2 phenotype, and the phenotypic individual serum may contain anti-A1 antibody.