α_1抗胰蛋白酶变异型Etokyo的基因结构特征

CHARACTERISATION OF THE GENE FOR THE Etokyo VARIANT OF α_1-ANTITRYPSIN

Etokyo型是东北亚地区蒙古人种特有的α_1抗胰蛋白酶(α_1-AT)变异型,也是我国北方汉族人群中最常见的α_1-AT变异型。采用PCR直接测序技术首次对Etokyo型的基因结构特征进行了分析,结果表明Etokyo基因的编码区第280位密码子发生了单碱基替换,即:GAC→TAC,所编码氨基酸由天门冬氨酸~280变为酪氨酸。讨论了Etokyo基因突变性质及该型在人群中的分布特点。

Etokyo type is a peculiar variant of α_1-antitrypsin (α_1-AT) in the Mongolian population of Northeast Asia. It is also the commonest α_1-AT variant in the population of North China. The characterization of Etokyo gene is unknown so far. By the PCR direct sequencing technique, the four coding exons of α_1-AT gene from 5 unrelated healthy individuals (four M_1 Etokyo phenotypes, one M_2 Etokyo phenotype) of Han nationality in Harbin region were studied. The result showed that Etokyo gene differed from the normal M_1 (val^(213))α_1-AT allele by a single base transversion of guanine to thymine, which resulted in the change from Asp^(280)(GAC) into Tyr (TAC). Although this point mutation is a neutral one,it may be implicated in micro-evolution of human races.