來源網址：http://tw.news.yahoo.com/article/url/d/a/090522/115/1jy1h.html女孩變女人 月經的基因找到了
更新日期:2009/05/22 08:58 楊舒婷
【記者楊舒婷綜合報導】青春期何時來？女孩何時變女人？肥胖是導致月經太早出現的原因？科學家已從基因裡找到答案！最新公佈於自然遺傳學雜誌(Nature Genetics)的研究報告指出，染色體6和9與女孩初次來潮的時間有密切關係；而太早來潮的女性，可能是因為擁有這兩對基因的變體。
女性有經期、分泌雌激素是為了繁衍目的，但雌激素也同時增加罹患心血管疾病、乳癌、骨質疏鬆等風險。因此，若女性越早進入青春期，罹患相關疾病的可能性就越高。
科學家表示，約有5%的女性帶有這兩組基因的變體，可能導致初次經期時間過早，比沒有變體的女性早約4至6個月。這項研究針對17,510名女性進行調查，發現她們初次來潮的時間和基因模組密切相關，與身高、體重也有對應關係。
經期過早更與罹患疾病、心理問題等息息相關。英國皇家醫學會成員、心理學家阿瑞克‧西格曼表示：「女性若過早進入青春期，易有沮喪、患得患失、挑釁、嗜菸酒或藥物、自信心不足等心理症狀，甚至有試圖自殺的傾向。」
不過，科學家也表示，雖然目前發現基因會影響進入青春期的時間，但營養攝取、運動等還是較主要的影響因素。
自然遺傳學雜誌(Nature Genetics)
May 2009, Volume 41 No 5 pp505-634相關文章中英翻譯
來源網址：http://www.yeeyan.com/articles/view/85455/42298/dzPuberty gene sets our sexual clocks
Puberty gene sets our sexual clocks
18:00 17 May 2009 by Ewen Callaway
Magazine issue 2709. Subscribe and get 4 free issues.
For similar stories, visit the Genetics Topic Guide
Some women's biological clocks tick faster than others, and now, researchers have uncovered the first genetic evidence to explain differences in the length of women's fertile lives.
The findings may indicate why some women go through puberty and menopause abnormally early or late. And eventually, the genes identified could lead to treatments for these conditions, as well as for diseases linked to prolonged or shortened fertility, such as breast cancer and osteoporosis, researchers say.
But the most immediate application of the discoveries will be to point biologists studying fertility in the right direction, says André Uitterlinden, a geneticist at Erasmus Medical Center in Rotterdam, the Netherlands.
"It's sort of the tip of the iceberg," says Uitterlinden, who led one of four groups that identified several variations in a gene called LIN28B that affect the timing of girls' first period, or menarche.
His team, as well as independent groups based in the UK, the US and Iceland, uncovered this gene's role by comparing genome-wide scans of thousands of women with their age at menarche.
Across hundreds of thousands of single letter differences peppered across the human genome, all four research teams found genetic variations near the gene LIN28B associated with earlier or later first periods.
Under development
Girls go through menarche between the ages of 9 and 16, and the variations in LIN28B accounted for just one to three months of these differences. For instance, one study found that Icelandic girls with two genetic letter Ts at a spot near LIN28B experience menarche 2.4 months earlier, on average, than girls with two Cs at that site.
Just how LIN28B might affect menarche isn't clear, says Ken Ong, a paediatrician at the Medical Research Council Epidemiology Unit in Cambridge, UK, who led another team.
The gene makes a protein that controls the quantities of other proteins a cell produces, and studies in roundworms suggest that the gene is involved in growth and development throughout life.
In humans, LIN28B seems to be involved in variations in adult height, as well. This helps explain why women who go through menarche later are taller than women who have their first period at a young age, says Uitterlinden. Indeed, two teams found that several other genes linked to height also predict age at menarche.
This points to a more general role for the LIN28B in puberty and adolescent development, than menstruation alone, says Ong. His team found a variant near the gene associated with earlier breast development in girls and, in boys, earlier voice-breaking. "Showing it in boys means [LIN28B] is more fundamental, not just to puberty, but to the timing of growth as well," he says.
Menopause control
Genes also play a role in menopause, and two research teams have identified several gene variants associated with advancing or delaying menopause by as much as two years.
As with menarche, these variants explain just a small percentage of the differences between the age at which women go through menopause, which range between about 40 and 60.
To find other genes associated with these traits, researchers will need to scan the genomes of even more women and look for less common genetic variations, says Kári Stefánsson, CEO of deCODE Genetics in Reykjavik, Iceland.
All four teams focused their hunts on gene variations found in at least 10 per cent of the population, while Stefánsson thinks that rarer variants may play a more significant role in menarche.
However, this shouldn't hinder efforts to understand the biology of menarche and menopause and eventually target them with drugs, he says. "The complexity of our biology is fairly limited, so it is highly likely that rare variants are going to affect the same biochemical pathways."
Journal references: Nature Genetics (DOI: 10.1038/ng.382; DOI: 10.1038/ng.383; DOI: 10.1038/ng.385; DOI: 10.1038/ng.386; DOI: 10.1038/ng.387)
生育基因设定性时钟
生育基因设定性时钟
埃文卡拉威写于2009年5月17日下午六点
类似的故事，请访问遗传学主题指南
有些妇女的生物钟比别人的走得快，而现在，研究人员们已经发现可以解释妇女们生育生活长短差异的首要基因依据。
研究人员说，研究结果可能表明，为什么有些妇女经历青春期和更年期异常早或迟。而且最终，这些被确定的基因能够引导出出对前述情况的治疗方法，而且也能引导出和生育延迟或缩短有联系的疾病，如乳腺癌或骨质疏松症的治疗方法。
“但对该发现的最直接的应用将是为研究生育的生物学家们指出正确的方向。”位于荷兰鹿特丹伊拉斯谟医学中心的遗传学家André Uitterlinden说。
“这有点像冰山一角，” Uitterlinden说 ，他领导了四个小组中的一组，这些小组辨认出了一种名为LIN28B基因的数种差异，而这些差异能影响女孩们的发育的第一阶段或月经初潮的时间。
他的团队和其他几个分别设立在英国、美国和冰岛的独立团队一样，通过对成千上万的处于月经初潮年纪的妇女们的染色体组的扫描情况进行比较而发现了这种基因的作用。
四个研究小组从纵横分布在人类基因组中的数以十万计的单字母的差异中发现了在基因LIN28B附近的基因变异会影响青春期的早晚。
在发展中
女孩们在9岁到16岁之间经历初潮，而这些年龄的差异中，其中一到三个月的差异是由基因LIN28B差异导致的。例如，一项研究发现，冰岛的女孩们在基因LIN28B附近某点有两个基因子母Ts，她们经历月经初潮的年纪平均比在该基因点是两个基因子母Cs的女孩们要早2.4个月。
“不过基因LIN28B会如何影响月经初潮目前尚不清楚，” Ken Ong说，他是一位位于英国剑桥的医学研究委员会流行病学室的儿科医师，领导着另一支团队。
这种基因能产生一种蛋白质，这种蛋白质能控制一个细胞能产生的其他蛋白质的数量，而且对蛔虫的研究表明，该基因参与整个生命的生长和发育阶段。
在人类中， 基因LIN28B似乎与成年人的身高差异也有联系。这有助于解释为什么妇女中经历月经初潮较晚的会比那些很年轻时就经历生命发育的第一阶段的女孩要高些，Uitterlinden这么说 。而事实上，两个小组发现，其他几个和身高有关的基因也能预测初潮的年龄。
这表明基因LIN28B在青春期和青少年的发育中有更广泛的作用而不仅仅是影响月经，Ong说。他的研究小组发现了在该基因附近的一个差异和女孩胸部发育提前及男孩的变声期提前有关。“男生身上的这些表现反映出LIN28B有着更根本的作用，不仅是对青春期，还对生长发育的时期有影响”。
更年期控制
基因对更年期也有影响，而且有两个研究小组发现了数个基因变异体可能导致更年期提前或者推迟能多达两年。
相对月经初潮而言，由这些基因变异造成妇女经历更年期的年龄差异，只占了这些年龄差异的一个小比例，因为妇女经历更年期的年纪从40岁到60岁。
为了寻找其他具有这些特性的其他基因，研究人员需要扫描更多妇女的基因组和寻找不太常见的遗传变异，位于冰岛的雷克雅未克的解密遗传学的首席执行官Kári Stefánsson说。
四个小组对基因变异的搜索集中在至少出现在占人口百分之十的人群中的基因变异，然而Stefánsson认为那些较少见的变异可能对月经初潮有更重要的作用。
然而，这不应阻碍我们努力去研究生物学的月经初潮和更年期，而且最终使药物与其挂钩。Stefánsson说，我们生物学的复杂程度相当有限，所以很有可能是一些罕见的变异会影响同一生化途径。 ”
白俄羅斯特殊體操隊選手漢娜（左）身材嬌小，被誤為是參賽選手的子女。
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