【摘要】 目的Ax是一种罕见的ABO亚型,其分子机理尚未完全阐明。本文以一个Ax亚型家系和一个无关的Ax亚型献血者个体为对象,研究中国人群Ax亚型的分子基础。方法ABO血清学定型、血浆N-乙酰-D-半乳糖胺基转移酶(A酶)活性测定、ABO基因7个外显子及其侧翼序列的PCR扩增、基因克隆和测序分析。结果DNA克隆和测序分析显示,家系先证者和无关献血者个体的ABO基因分别为A/O01和A/O02基因型,在第7外显子均存在426G>C杂合突变,导致N-乙酰-D-半乳糖胺基转移酶的氨基酸发生M142I改变。在120个正常样本中未检出此突变。结论ABO基因426G>C突变导致的N-乙酰-D-半乳糖胺基转移酶第142位氨基酸置换改变了酶的保守区域,从而降低了酶的催化活性,导致Ax表现型。本突变为国际首次报道。更多还原

【Abstract】 Objective:Ax is a very rare ABO blood group phenotype and the molecular mechanism underlying it still remains largely unknown.In this study,we studied the molecular basis of Ax subgroup in Chinese population by a Ax Chinese family and an unrelated Ax Chinese donor.Method:Serologic investigations were performed including serum transferases activity assay.DNA sequences of all 7 exons and exon-intron boundaries of ABO gene were analyzed using genomic DNA by polymerase chain reaction(PCR)and direct DNA sequencing or sequencing after gene cloning.Result:DNA analysis revealed that the ABO gene of the proband and the unrelated donor were heterozygous of A/O01 and A/O02 alleles.A novel mutation 426G>C was identified in A allele,which resulted in the amino acid changes M142I in the A glycosyltransferase.Conclusion:Amino acid substitutions resulted from novel mutations 426G>C on ABO gene change highly conserved regions of the enzyme and may reduce the activity of the glycosyltransferases,leading to the Ax phenotype.更多还原