中国汉族人群人类白细胞抗原新等位基因A*1155的确认

背景：在国内发现的新等位基因中，大部分都是先采用人类白细胞抗原分型低分辨方法进行分型，如发现反应格局异常后，再进一步用基因测序或基因克隆方法进行确认，这样有可能导致一些新等位基因未被发现。基因测序分型方法被认为是人类白细胞抗原分型的金标准，它可得出精确的核苷酸序列。 目的：直接采用基因测序分型方法对中华骨髓库标本进行检测，识别和确认中国汉族人群中新发现的等位基因。 方法：应用中国造血干细胞捐献者测序结果可疑为新等位基因的重采血样5 mL，采用基因测序分型技术，发现一样本HLA-A位点的杂合结果HLA-A*030101/A*110101在外显子上有1个位置与数据库不符，为了区别哪一个为新等位基因，采用基因克隆(TOPO TA Cloning)技术对两个等位基因1-8外显子进行DNA双向测序，发现1个与HLA-A*110101序列相近的新等位基因，分析两者核苷酸序列的差异。并将测序结果与已知人类白细胞抗原等位基因序列比较分析。 结果与结论：通过克隆分离杂合等位基因，再进行测序确认发现新的序列与A*110101相比，在第2外显子第330碱基位置上C→G，密码子86AAC→AAG，发生了氨基酸的改变，由天冬酰氨变为赖氨酸。提示该等位基因为新的HLA-A等位基因，2009-10-31被世界卫生组织人类白细胞抗原因子命名委员会正式命名为HLA-A*1155。

Identification of a novel human leukocyte antigen allele A*1155 in a Chinese Han population

BACKGROUND: Most of novel alleles in China are found due to abnormal reaction patterns in low-resolution human leukocyte antigen (HLA) typing and identified by further gene sequencing or gene cloning. Thus, some novel alleles may be missed. Gene sequencing is considered to be the golden standard for HLA typing, which can obtain exact nucleotide sequence. OBJECTIVE: To detect the samples in Chinese Bone Marrow Bank by gene sequencing typing, and to identify novel allele in Chinese Han population. METHODS: Blood (5 mL) suspected as a new gene were redraw. An unknown HLA-A allele was detected by sequence-based typing (SBT) in a Chinese bone marrow donor. SBT showed that there was 1 difference compared with database in exon 2. Its anomalous patterns suggested the possible presence of either a novel A*03 or a novel A*11. To separate the two alleles and to determine whether the allele was novel, TOPO TA cloning was performed. The sequencing result was compared with known HLA allele sequence. RESULTS AND CONCLUSION: Heterozygous allele was separated by cloning. A novel allele was identified with sequencing. The novel allele was most similar to A*1155 except for one nucleotide exchange in exon 2 at position nt 330 C>G, codon 86 N (AAC)>K (AAG), resulting in amino acid exchange. This allele is a novel HLA-A allele and has been officially named HLA-A*1155 by the Nomenclature Committee of World Health Organization on 31 October 2009.