ABO变异型B305血型基因亚型的鉴定及序列分析

Indentification and Sequence Analysis of A Individual with B305 Blood Group Gene Subtypes of ABO Variant

目的:研究和鉴定1例ABO变异型B3亚型的分子生物学特性。方法:在标准血型血清学方法鉴定的基础上,采用聚合酶链反应-序列特异性引物(PCR-SSP)、ABO基因第6、7外显子PCR产物直接测序及克隆测序等方法进行ABO亚型基因分型和序列分析。结果:先证者红细胞含有弱B抗原,同时血清中含有抗-A抗体。PCR-SSP结果显示样本基因型为BO1。直接测序分析发现261del G,297A/G、425 T/C、526C/G、657C/T、703A/G、796C/A、803G/C和930G/A 8个位点杂合。克隆测序得到两个等位基因B305和O01。B305等位基因序列与B101等位基因序列比对仅第425位碱基为T>C突变,导致多肽链M142T替换。结论:α-1,3半乳糖基转移酶基因425位碱基T>C突变产生B305等位基因,导致B抗原表达减弱。

Objective：To investigate and identify the molecular and biological characteristics of B305 blood group gene subtypes of a ABO variant.Methods：The individual was confirmed by standard serological techniques.The genotyping and sequencing were performed by using polymerase chain reaction-sequence specific primer（PCR-SSP）,direct sequencing and gene cloning for Exon 6 and exon 7 of ABO locus respectively.Results：B antigen was detected on red blood cells of the proband and there was anti-A antibody in the serum.The PCR-SSP result showed B01 phenotype.DNA sequencing showed 261 delG,297A/G,425T/C,526C/G,657C/T,703A/G,796C/A,803G/C and 930G/A heterozygote in exon 6 to exon 7.After cloning and sequencing,2 alleles B305 and 001 were obtained.The sequence of B305 allele had one nucleotide mutation（T to C） at position 425 compared with that of B101 allele,resulting in an amino acid substitution（M142T）.Conclusion：T 〉 C at nt425 of α-1,3 galactosyltransferase gene can result in B305 blood group gene subtypes,which reduce the expression of B antigen.