Annals Human Genet.：发现中国人特有解酒基因

2011/07/13 20:07:16

中国人的基因中存在能够分解酒中毒素的基因，且这种基因仅存在于中国人及与中国人有关的人群，如韩国、日本等东亚人群中间——复旦大学人类遗传学实验室、生命科学学院副教授李辉课题组昨天宣布了这一有趣的发现。

据介绍，因为这种基因的形成年代与“杜康酿酒”这一历史故事的时间相吻合，因此被专家戏称为“杜康基因”。

“杜康基因”学名是乙醇脱氢酶第七亚族基因（ADH－1－B）,与酒精及一些相关毒素的解毒功能相关，乙醇脱氢酶的功能主要是将人体摄入的酒精分解为乙醛，乙醛在人体内另一种乙醛脱氢酶的作用下进一步被分解为乙酸，而乙酸是人体内众多代谢反应需要的底物,这就完成人体对酒精的解毒功能。

为什么在欧洲同样有很多人饮酒，却没有发现乙醇脱氢酶第七亚族基因？对此，李辉解释说，虽然都是酒，但是欧洲的酒主要是由水果类酿造的，而东亚人群的酒是由粮食酿造的，这存在比较大的差别。另外，欧洲直到中世纪农业都不发达，用于酿酒的粮食很少。因此，酒精对欧洲人群中基因的选择时间短，作用很弱。这也解释了我国很多以游牧为主的少数民族不存在这种基因的原因。

既然东亚人群中有分解酒精能力特别强的乙醇脱氢酶第七亚族基因，那么是不是东亚人在饮酒时就可以随心所欲呢？对此，李辉的回答是否定的。他表示，虽然70％东亚人体内有乙醇脱氢酶第七亚族基因，但是这种基因只能是将酒精分解为乙醛，乙醛还是对人体有毒性的，很多人喝酒脸红就是由于乙醛刺激的原因。要想将乙醛彻底分解为无毒的乙酸，还需要另一种乙醛脱氢酶，但奇怪的是这种酶在东亚人群中又有70％的人没有。所以，尽管很多人不会发生酒精中毒，但会发生乙醛中毒。

研究只是向我们从一个侧面揭示了人类进化的有趣故事。为了健康，还是应该尽量少饮酒。

Diversification of the ADH1B Gene during Expansion of Modern Humans

Hui Li, Sheng Gu, Yi Han, Zhi Xu, Andrew J. Pakstis, Li Jin, Judith R. Kidd, Kenneth K. Kidd

Annals of Human Genetics   DOI: 10.1111/j.1469-1809.2011.00651.x

A variant allele, ADH1B48His, also known as ADH1B2, at the human Alcohol Dehydrogenase 1B gene (ADH1B) is strongly associated with alcoholism in some populations and has an unusual geographic distribution. Strong evidence implies selection has increased the frequency of this allele in some East Asian populations but does not fully explain its geographic pattern. We have studied haplotypes of 10 single nucleotide polymorphisms (SNPs) and two short tandem repeat polymorphisms (STRPs) in the ADH1B region in 2,206 individuals from a worldwide set of populations. These SNPs and STRPs define nine common haplogroups most of which have distinct geographic patterns. The haplogroups H5 and H6, both with the derived ADH1B*48His allele, appear restricted to the Middle East and East Asia, respectively. The positively selected H7 is derived from H6 by a new regulatory region variant defining SNP rs3811801 restricted to East Asia. Age estimates of the haplogroups based on the STRPs also agree with the time of the migration events estimated by other studies. H7 is estimated to have expanded recently, around 2,800 years ago, and ancient DNA samples from North China confirm its presence about that time. The dating of the H7 expansion may help understand the selective force on the ADH1B gene.