英国科学家在The American Journal of Human Genetics上发表最新文章，发现人类的基因中每200个基因中有1个基因是多余的！
该研究论文的通讯作者是Chris Tyler-Smith，Chris研究小组从整个基因组的水平分析基因的无意义的单核甘酸突变给基因带来的影响，研究发现，在终止密码子中无意义单核甘酸的突变可能导致基因无法表达目的蛋白或是表达功能不全的蛋白甚至是有害的蛋白产物。
研究小组从全世界范围内研究了上1000人的遗传密码子，研究关注的焦点是单个碱基的变化（单个核苷酸的变化），尤其是这些变化对蛋白表达所造成的影响是关注的焦点。研究者将这些变化称为无意义SNP（nonsense SNP），这些无意义的突变也许对人体造成不利的影响。
研究者称，这些变化也许与人类的某些遗传疾病有密切的关系，但是令人惊讶的是，这种无意义的突变在普通的人群中很普遍。平均每个人发生这样的突变约有46次。
人类基因组包含有约20,000个基因，其中有99个基因发生SNP突变，意味着在每200个基因中至少有1个基因变成多余的无意义的；而另外的一些无意义SNP突变发生在167个基因中，其中有8个突变数据出现在人类基因突变数据中，这8个突变与遗传疾病有关联。
研究者发现有些基因的丢失对人类的健康和进化没有影响，比如说，在亚洲，丢失MAGEE2基因对健康没有影响。
Chris说，也许基因学也存在less is more的定理。
这项研究为基因组学研究提出了一个新的问题：基因的丢失对人类健康和进化有何影响？（生物谷Bioon.com）
生物谷推荐原始出处：
The American Journal of Human Genetics, 05 February 2009 doi:10.1016/j.ajhg.2009.01.008
A Genome-wide Survey of the Prevalence and Evolutionary Forces Acting on Human Nonsense SNPs
Bryndis Yngvadottir1,Yali Xue1,Steve Searle1,Sarah Hunt1,Marcos Delgado1,Jonathan Morrison1,2,Pamela Whittaker1,Panos Deloukas1andChris Tyler-Smith1,,
1 The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambs CB10 1SA, UK
2 Present address: Cancer Research UK, Genetic Epidemiology Unit, Strangeways Research Laboratory, Worts Causeway, Cambridge CB1 8RN, UK
Nonsense SNPs introduce premature termination codons into genes and can result in the absence of a gene product or in a truncated and potentially harmful protein, so they are often considered disadvantageous and are associated with disease susceptibility. As such, we might expect the disrupted allele to be rare and, in healthy people, observed only in a heterozygous state. However, some, like those in the CASP12 and ACTN3 genes, are known to be present at high frequencies and to occur often in a homozygous state and seem to have been advantageous in recent human evolution. To evaluate the selective forces acting on nonsense SNPs as a class, we have carried out a large-scale experimental survey of nonsense SNPs in the human genome by genotyping 805 of them (plus control synonymous SNPs) in 1,151 individuals from 56 worldwide populations. We identified 169 genes containing nonsense SNPs that were variable in our samples, of which 99 were found with both copies inactivated in at least one individual. We found that the sampled humans differ on average by 24 genes (out of about 20,000) because of these nonsense SNPs alone. As might be expected, nonsense SNPs as a class were found to be slightly disadvantageous over evolutionary timescales, but a few nevertheless showed signs of being possibly advantageous, as indicated by unusually high levels of population differentiation, long haplotypes, and/or high frequencies of derived alleles. This study underlines the extent of variation in gene content within humans and emphasizes the importance of understanding this type of variation.
