一例ABO亚型ABx09的分子生物学研究和鉴定

目的 研究1例ABO亚型ABx09的分子机制.方法 应用单克隆抗体检测先证者红细胞ABO血型抗原,标准A、B、O红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)技术分别扩增先证者ABO基因的第1～7外显子序列,PCR产物经酶切后直接测序分析.第5～7外显子扩增产物经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5～7外显子双向测序分析.家系调查采集先证者父母的标本进行血型血清学实验和ABO基因第6和7外显子直接测序分析.结果 先证者红细胞有A、B抗原,同时血清中存在抗B抗体.直接测序分析发现第6外显子第261位无缺失、第297位AG,第7外显子467CT、526CG、657CT、703GA、796CA、803GC、889GA、930GA杂合,可指定为A102Bx09基因型.克隆测序得到两个等位基因A102和Bx09.与B101序列相比,Bx09第889位G→A,导致第297位谷氨酸变成赖氨酸.家系调查显示先证者Bx09等位基因从母亲遗传所得.结论 α-1,3-半乳糖基转移酶基因第889位G→A突变导致产生Bx09表型,其血清中可含有抗B抗体.

Identification of an ABx09 phenotype of ABO subtype

Objective To analyze the molecular basis for an individual with ABx09 phenotype of ABO subtype.Methods The ABO group antigens on red blood cells of the proband were identified by monoclonal antibodies,and the ABO antibody in serum was detected by standard A,B,O cells.The exons 1-7 of ABO gene were amplified by polymerase chain reaction (PCR) respectively and the PCR products were sequenced directly.The amplified products for exons 5-7 were also cloned by TOPO TA cloning sequencing kit to split the two alleles apart,selected colonies were sequenced bidirectionally for exons 5-7 of the ABO gene.The samples of the proband's parents were collected,then serological test of the blood group and sequence analysis for exons 6-7 of ABO gene were preformed.Results Both A and B antigens were detected on red blood cells of the proband and there was anti-B antibody in the serum.There was no G deletion at position 261,while 297AG in exon 6,467CT,526CG,657CT,703GA,796CA,803GC,889GA and 930GA heterozygote in exon 7 were detected by direct DNA sequencing,which can be assigned for A102Bx09 genotype.After cloning and sequencing,two alleles A102 and Bx09 were obtained.The sequence of Bx09 had one nucleotide changes (G to A) at position 889 compared with that of B101,which resulted in an amino acid change of Glu to Lys at 297 position.The Bx09 in the proband was inherited from her mother by family investigation.Conclusion G→A at nt889 of α-1,3 galactosyltransferase gene can result in Bx09 phenotype,with the presence of anti-B antibody in serum.