個子矮小乃基因數(shù)量不足之過

　　A shortage of genes could be to blame for the lack of height in short people, researchers have found。

　　Two studies involving 12,000 people has been carried out in America and found a link between the amount of missing genetic material and a decrease in height。

　　Height is mostly passed down through families but scientists say this does not explain everything when comparing the variations between people。

　　Dr Joel Hirschhorn, who led a study published in the American Journal of Human Genetics, said: "Despite tremendous recent progress in finding common genetic variants associated with height, thus far these variants only explain about 10 percent of the variation in adult height."

　　Researchers now believe that missing copies of genes or other sections of DNA could be the reason behind up to half of the genetic impact on people's height。

　　Known as copy number variants (CNV)， the genetic abnormalities are alterations within the chromosome which means a cell has an excess or an absence of a slice of DNA。

　　Some CNVs are common, but others are rare or occur with low frequency among humans。

　　And the researchers found an excess of low frequency CNV deletions - where part of the genome is missing - in shorter people。

　　There is a wide variation in the amount of these CNV deletions which people have in their genome, with some people having several million。

　　The researchers from the Children's Hospital Boston found that for every million individual deletions, one eighth of an inch in height was lost in people。

　　據(jù)英國《每日郵報(bào)》11月24日報(bào)道，研究人員發(fā)現(xiàn)，基因數(shù)量不足可能是人身高較低的原因。

　　在美國進(jìn)行的兩項(xiàng)涉及1.2萬人的調(diào)查研究發(fā)現(xiàn)了缺失基因的數(shù)量與身高降低之間的關(guān)系。

　　身高主要通過家族遺傳，但是科學(xué)家說，在比較人與人之間的不同之處時，這個原因并不能解釋所有問題。

　　喬爾·何塞豪恩主持了這項(xiàng)研究，研究成果發(fā)表在美國的《人類遺傳學(xué)》雜志上，他說：“盡管一般的遺傳變異與身高方面關(guān)聯(lián)的研究近期取得了重大的進(jìn)展，但迄今為止，這種遺傳變異僅僅能解釋10%的成年人身高變化的原因。”

　　研究人員現(xiàn)在認(rèn)為，成人在身高方面受基因影響的背后原因，有一半可能是因?yàn)槿笔Щ�因副本或是DNA組成部分。

　　被稱為拷貝數(shù)變異(CNV)的基因異常是染色體內(nèi)部的改變。這意味著，一個細(xì)胞可能會多出或缺少一片DNA。

　　有些拷貝數(shù)變異是很常見的，但還有一些則在人類中極少發(fā)生或是發(fā)生的頻率較低。

　　研究人員發(fā)現(xiàn)，在個子比較矮的人身上，會出現(xiàn)低發(fā)生率拷貝數(shù)變異過剩——部分基因組缺失。

　　人類基因組拷貝數(shù)變異缺失在數(shù)量上也有很大的不同，有些人的缺失數(shù)甚至能達(dá)到幾百萬。

　　波士頓兒童醫(yī)院的研究人員發(fā)現(xiàn)，每一百萬個基因缺失就會使身高下降八分之一英寸。