Nature发布颠覆性成果：近亲婚配会影响什么？

　　

一项重要的国际研究发现，由来自不同遗传背景的父母所生的孩子往往会比其他人更高，且具有更敏锐的思考能力。相关的研究论文发布在7月1日的《自然》(Nature)杂志上。

研究人员分析了来自世界各地100多项研究的健康和遗传信息。其中包括来自城市和乡村35万多人的详细资料。

研究小组发现，更大的遗传多样性与身高增长之间有关联。它也与更好的认知能力，以及更高的教育程度有关。

但遗传多样性不会影响诸如高血压或胆固醇水平等因素——它们会影响个体形成心脏病、糖尿病和其他复杂疾病的几率。

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来自爱丁堡大学的研究人员检测了一些个体的完整遗传组成。他们指出在一些情况下人们遗传了来自父母的相同的基因拷贝——这表明他们的祖先有亲缘关系。

而个体基因中少有这种情况者，表明他们的遗传物质具有更大的遗传多样性，父母双方的家庭不太可能是远亲。

过去人们认为近亲结合会提高个体罹患复杂疾病的风险，然而研究人员发现事实并非如此。他们发现唯一受到遗传多样性影响的性状就是身高和更敏捷的思考能力（延伸阅读：澳遗传学家研究称近亲结婚健康风险被严重夸大 ）。

研究结果表明随着时间的推移，进化帮助了人们提高身高和更敏锐的思维能力，但却没有影响他们罹患一种严重疾病的倾向。

爱丁堡大学Usher研究所的Jim Wilson说：“这项研究突显了通过大规模遗传分析来揭示我们进化史基本信息的能力。”

爱丁堡大学Usher研究所的Peter Joshi博士说：“我们的研究解答了达尔文率先提出的关于遗传多样性利益的问题。下一步我们将把注意力放在从遗传多样性中受益最多的基因组特异区域上。”

生物通推荐原文摘要：

Directional dominance on stature and cognition in diverse human populations

Homozygosity has long been associated with rare, often devastating, Mendelian disorders1, and Darwin was one of the first to recognize that inbreeding reduces evolutionary fitness2. However, the effect of the more distant parental relatedness that is common in modern human populations is less well understood. Genomic data now allow us to investigate the effects of homozygosity on traits of public health importance by observing contiguous homozygous segments (runs of homozygosity), which are inferred to be homozygous along their complete length. Given the low levels of genome-wide homozygosity prevalent in most human populations, information is required on very large numbers of people to provide sufficient power3, 4. Here we use runs of homozygosity to study 16 health-related quantitative traits in 354,224 individuals from 102 cohorts, and find statistically significant associations between summed runs of homozygosity and four complex traits: height, forced expiratory lung volume in one second, general cognitive ability and educational attainment (P < 1 × 10−300, 2.1 × 10−6, 2.5 × 10−10 and 1.8 × 10−10, respectively). In each case, increased homozygosity was associated with decreased trait value, equivalent to the offspring of first cousins being 1.2 cm shorter and having 10 months’ less education. Similar effect sizes were found across four continental groups and populations with different degrees of genome-wide homozygosity, providing evidence that homozygosity, rather than confounding, directly contributes to phenotypic variance. Contrary to earlier reports in substantially smaller samples5, 6, no evidence was seen of an influence of genome-wide homozygosity on blood pressure and low density lipoprotein cholesterol, or ten other cardio-metabolic traits. Since directional dominance is predicted for traits under directional evolutionary selection7, this study provides evidence that increased stature and cognitive function have been positively selected in human evolution, whereas many important risk factors for late-onset complex diseases may not have been.