HLA-DRB1*1218新等位基因克隆测序鉴定及内含子序列分析

目的 鉴定中国人群人类白细胞抗原(human leukocyte antigen,HLA)DRB1基因,分析新等位基因第1和2内含子序列信息.方法 采用聚合酶链反应-序列特异寡核苷酸探针反向杂交法(polymerase chain reaction-sequence specific oligonucleotide probes,PCR-SSOP)对广东地区随机正常人群进行HLA常规基因分型,发现1个与HLA-DRB1*120201相近的未知基因,对先证者DNA应用组特异性引物扩增HLA-DRB1位点第2外显子,PCR产物经克隆到质粒载体中以获得单链,对克隆所得产物进行HLA-DRB1基因的第2外显子及第1和第2内含子双向测序分析.并与DRB1*120201基因序列的第2外显子和DRB1*03010101等位基因内含子相比较.结果 发现该个体的一个HLA-DRB1*080302基因被确认,而另一个HLA-DRB1基因为新等位基因,其序列被GenBank接受(编号为FJ481086).新等位基因与最相近的DRB1*120201相比,在第2外显子上有1个核苷酸的不同,即第262位G→C(密码子59 GAG→CAG,氨基酸59 Glu→Gln).DRB1*1218与DRB1*03010101等位基因第2内含子序列完全相同,而与DRB1*03010101等位基因第1内含子序列相比较有12个碱基不同.结论 发现并鉴定一个新的HLA等位基因,经世界卫生组织HLA因子命名委员会正式命名为HLA-DRB1*1218.

Identification of a novel allele HLA-DRB1*1218

Objective To identify a novel human leukocyte antigen (HLA) allele by cloning and sequence-based typing in Chinese population, and analyzing the sequence of the introns 1 and 2. Methods The routine HLA-A, -B, -DRB1 low resolution genotyping for stem cell donor from Guangdong province was performed with polymerase chain reaction-sequence specific oligonucleotide probes (PCR-SSOP). An unknown HLA-DRB1 allele was initially detected by HLA typing. Genomic DNA of the proband was amplified by using HLA-DRB1 locus group-specific primer, the amplified product was cloned, sequenced, and compared to the closest DRB1 * 120201 allele and the closest intron sequence of the DRB1 * 030101 allele. Results The sequencing results showed that a normal DRB1 * 080302 and a novel DRB1 * 1218 variant allele were identified. The sequence of the novel allele has been submitted to GenBank (FJ481086). The novel allele had 1 nucleotide substitution of the closest matching allele HLA-DRB1 * 120201 at nt262(G →C) in exon 2, resulting in an amino acid change from GIu(GAG)→Gln (CAG) at codon 59. The intron 2 sequence is identical between the novel HLA-DRB1 * 1218 and DRB1 * 030101, but there are 12 nucleotides substitution in intron 1. Conclusion A novel HLA allele was confirmed by cloning and sequence-based typing in Chinese. It was officially designated as HLA-DRB1 * 1218 by WHO Nomenclature Committee.