Bel亚型α1，3半乳糖基转移酶新等位基因的鉴定

Identify a novel B subgroup allele of al, 3 galactosyltransferase

目的分析1例罕见B放散型的ABO血型分子背景，鉴定ABO新等位基因。方法对1例正反定型未能鉴定其ABO血型的捐血者，分别采用ABO基因第6及第7外显子直接序列测定及单倍体克隆测序进行基因分型，以及检测AB0基因CBF／NF—Y微卫星增强子区域。结果血清学鉴定为Bel的个体中发现了一个突变的B等位基因，该等位基因与B101等位基因相比，差异在nt905位A〉G突变。该突变导致αl，3半乳糖基转移酶Asp302gly，定为Bel新基因，Genbank注册号为FJ009674。AB0基因微卫星增强区域序列测定为G／C型。结论α1，3-D-半乳糖基转移酶基因中nt905A〉G突变可能是Bel分子遗传机制之一，第302位氨基酸变异大大影响了糖基转移酶的活性。

Objective To analyze the ABO genetic background in a rare B elution subtype and identify a novel ABO allele. Methods One sample with discrepancy of serological tests was directly sequenced for Exon 6 and Exon 7 at ABO locus and its haploid types. The genomic DNAs were further detected for the CBF/NF-Y ministatellite enhancer region of ABO gene. Results A novel B allele was identified in a Bel individual. The B allele was different from the common B101 allele by n905A〉G missense mutation, which resulted in an amion acid change from Asp to Gly at 302 locus. The allele was defined as Bel new allele and registered as number FJ009674 on Genbank. The sample had four 43-bp minisatellite repeats within the CBF/NF-Y enhancer region with G/C type. Conclusion 905A 〉 G mutation in the αl, 3 galactosyltransferase may be one of genetic bases of Bel phenotype. The change of amino acid at 302 locus may greatly affect the activity of galactosyltransferase.