一例ABO亚型Ax28新等位基因的鉴定

Identification of a novel Ax allele of the ABO blood group

目的研究ABO血型新等位基因Ax28的分子机制。方法应用单克隆抗体检测样本的红细胞ABO血型抗原,标准A、B、O红细胞检测血清中ABO抗体。PCR技术扩增ABO基因7个外显子及其邻近内含子序列后测序,对第5~7外显子扩增产物进行克隆后测序。结果先证者红细胞有弱A抗原,同时血清中存在抗A和抗B抗体。直接测序分析发现第6外显子第261位杂合缺失,第7外显子在467C>T、830T>C杂合突变。克隆测序得到两个等位基因O01和Ax28。与A102序列相比,Ax28第830位T>C突变,导致第277位缬氨酸变成丙氨酸。结论N乙酰氨基半乳糖基转移酶基因第830位T>C突变可能引起酶活性减弱,进而导致产生Ax28变异型。

Objective To explore the molecular basis for an individual with Ax28 phenotype of the ABO subtype.Methods The ABO group antigens on red blood cells of the proband were identified by monoclonal antibodies.The ABO antibody in serum was detected by standard A,B,O cells.Exons 1to 7of the ABO gene were respectively amplified by PCR and directly sequenced.Amplicons for exons 5 to 7 were also sequenced after cloning.Results Weakened A antigen was detected on red blood cells from the proband.Both anti-A and anti-B antibodies were detected in the serum.Heterozygous 261G/del was detected in exon 6,while heterozygous 467C/T and 830T/C were detected in exon 7 by direct DNA sequencing.After cloning and sequencing,two alleles (O01 and Ax28)were obtained.Compared with A102,the sequence of Ax28contained one nucleotide changes (T to C)at position 830,which resulted in amino acid change (Val to Ala)at position 277.Conclusion The novel mutation c.830T>C of the galactosaminyltransferase gene may give rise to the Ax28phenotype.