A New Genetic Test Technology
一项新的基因检测技术
A new genetic test can reveal the hair colour of unseen criminal suspects or unidentifiable victims.
一项新的基因检测技术可以显示未见过的犯罪嫌疑人或无法鉴定的受害人的头发颜色。
The new analysis used a collection of recently discovered mutations linked to hair colour, and it can predict the hue of an unknown person's hair with about 80 to 90 percent accuracy.
这项新的分析技术使用的是一组最近发现的与头发颜色有关的基因变异数据，它能预测陌生人头发颜色的准确率高达80%到90%。
"This could be really useful in cases with no eyewitnesses, where police have no idea who to look for at all," said human geneticist Manfred Kayser at Erasmus Medical Centre in the Netherlands, who led the study to be published in an upcoming issue of Human Genetics.
来自荷兰伊拉兹马斯医学中心的人类遗传学家曼弗雷德·凯瑟说一旦出现现场没有目击证人而警方也找不到任何线索的情况，这种技术就真的太有帮助了"。这是在即将出版的《人类基因》中的一项研究课题，而曼弗雷德则是该课题的带头人。
Forensic investigators extract DNA from blood, bones, spit, semen and other bodily stuff left at crime scenes, then check for matches in genetic databases. Until the past decade or so, unmatched samples weren't immediately helpful in crime solving. Recent genetic research , however, has buoyed DNA's forensic value by identifying markers linked to age, eye colour, skin colour and hair colour.
法医先从罪犯留在案发现场的血液、骨头、唾液、精液及其他人体组织中提取DNA，然后拿到基因数据库内进行比对配组。大约在过去的十年中，未比对配组的提取样没能给侦破案件带来立竿见影的效果，然而近期的基因研究中，基因鉴定与年龄、眼睛、皮肤及头发颜色产生了联系，这使得DNA的法医作用更加突显。
Two types of melanin pigments, one light and one dark, control hair's basic shades. Most people produce only the dark melanin, resulting in black hair. But people of European descent can produce the lighter melanin and have red hair colours, or produce some combination of both for blond hair colours.
人体有两种黑色素，一种色浅，一种色深，它们共同决定着头发的色度。绝大部分人只能生成深色黑色素，结果就长出了黑色头发。但是有着欧裔血统的人则产生浅色黑色素，因而有红色或红黑混杂的金色头发。
More subtle shade differences are controlled by a mutation called a single nucleotide polymorphism, or SNP, which is single change to one of 3 billion base pairs in the human genome. While many have no detectable effect on the body, some cause disease or result in visible changes such as hair coloration.
头发更为细微的差别是受一种叫做单碱基多态位点(或称做SNP)的变异控制，这种SNP变异是人体3亿基因组碱基对的单变。一些变异的效果还未在人体中检测出来，但有些会引发疾病，有些会引起看得见的变化，比如说头发的颜色。
Such mutations are common in DNA but very stable, Kayser said, because the chance one will be erased is roughly one in 100 million generations. SNPs linked to hair colour are even more stable because they' re visible, and people tend to gravitate toward mates with specific hair colours.
凯瑟称，这种变异在DNA中很常见，也很稳定，因为在1亿个基因组中一个碱基对被消除的机会是很难的;而与发色相关联的SNP则更为稳定，因为这些SNP是可见的，并且人们往往倾向于以头发的颜色来吸引伴侣。
Tracking down SNPs that affect physical appearance is akin to looking for needles in a haystack, but new large-scale genomic analyses have identified dozens of hair colour markers.
想要查找SNP基因会对人体的外观产生怎样的影响，这就犹如在稻草堆里找针，非常不容易;但新近的大规模基因分析已鉴别出几十种头发颜色的生成物质。
To see if hair colour could be predicted using 45 SNPs from 13 genes, Kayser and his team sampled DNA from 385 Polish volunteers and had dermatologists record their hair colour. Their testing singled out 13 SNPs on 11 genes that could predict red and black hair colours with about 90 percent accuracy, as well as blond and brown colours with better than 80 percent accuracy.
为了察看头发颜色是否可由13个基因中的45个SNP中进行预测，凯瑟和他的研究小组从385名波兰志愿者身上提取DNA样本，并由皮肤专家记录其头发颜色。他们的检测从11个基因中分辨出13个可以预测红、黑色头发的SNP，准确率达90%;同时，预测黄、褐色头发的准确率也高于80%。
"I don't see this as going to court kind of evidence, but as an investigative lead it's strong and could work in some scenarios really well," said forensic scientist Bruce Budowle of the University of North Texas at Fort Worth, who was not involved in the study.
"我看这不能用作出庭的证据，但作为一项研究领域，在某些场合它确实能发挥作用。"来自美国沃思堡北德克萨斯州大学的法医科学家布鲁斯·巴道乌尔说，他没有参与这项研究。
In addition to helping describe mystery suspects, said Budowle, a former FBI senior scientist, the new test should help artists create better renderings of unidentifiable victims. "A physical resemblance that's strikingly good is much better than a more abstract one. Hair colour may be all it takes to push someone over the edge," Budowle said.
此外，巴道乌尔，这位同时也是联邦调查局前高级科学家说"除了可以帮助描绘出神秘的嫌疑犯外，这项新式检测技术还能帮助艺术家们更好地创造出受害人复原图。客观的物理相似性总比抽象的东西好，而头发颜色就具备这样优势，很有可能在关键时把某些人定罪。"
The new model's accuracy could be improved by testing it on bigger and different populations. Finding more SNPs linked to hair coloration with genome-wide analyses may also help, but such efforts are expensive.
这项新模式的准确性还需要经过对更多不同人的试验来提高。用全基因组分析的方法查找更多与头发色度相关联的SNP或许有用，但这样做费用太高。
"Given the complexity of hair coloration and our sample size, I'm pretty amazed at how accurate it is," Kayser said.
凯瑟说，"给出复杂的头发色度，再拿出我们的样本，我真为它是如此精确而感到惊讶。"