好英语网40岁当爹儿女易自闭
Older men are more likely than young ones to father a child who develops autism or schizophrenia, because of random mutations that become more numerous with advancing paternal age, scientists reported on Wednesday, in the first study to quantify the effect as it builds each year. The age of mothers had no bearing on the risk for these disorders, the study found.
周三发表的一份科学报告显示，男性年龄越大，所生育的子女患自闭症和精神分裂症的几率也会随之增大。这是因为，随着年龄增长，随机的基因变异也越多。这是科学家第一次量化研究父亲年龄对新生儿患病机率的影响。研究还发现，母亲的年龄与孩子患上述疾病的几率无关。
Experts said that the finding was hardly reason to forgo fatherhood later in life, though it may have some influence on reproductive decisions. The overall risk to a man in his 40s or older is in the range of 2 percent, at most, and there are other contributing biological factors that are entirely unknown.
专家说，年长的男性大可不必因为这项研究的结果而放弃当父亲，但这也许会影响他们关于生育下一代的决定。 男人在40多岁或更年长时要孩子的话，总体风险最高是2%，此外还有一些完全未知的生理因素也会产生影响。
But the study, published online in the journal Nature, provides support for the argument that the surging rate of autism diagnoses over recent decades is attributable in part to the increasing average age of fathers, which could account for as many as 20 to 30 percent of cases.
但是，这项在《自然》(Nature)杂志网站发表的研究支持了这样一种观点，即自闭症的确诊率在近几十年来快速上升，部分是由于男性作父亲的平均年龄的提高，有20-30%的病例与此有关。
The findings also counter the longstanding assumption that the age of the mother is the most important factor in determining the odds of a child having developmental problems. The risk of chromosomal abnormalities, like Down syndrome, increases for older mothers, but when it comes to some complex developmental and psychiatric problems, the lion’s share of the genetic risk originates in the sperm, not the egg, the study found.
这次研究的发现也反驳了长期存在的一种观点，即认为母亲的年龄是决定孩子出现发育问题几率的最重要因素。大龄母亲会增加染色体异常的风险，如唐氏综合征。但是，当涉及一些复杂的发育和精神问题时，研究发现大部份的遗传风险源于精子，而不是卵子。
Previous studies had strongly suggested as much, including an analysis published in April that found that this risk was higher at age 35 than 25 and crept up with age. The new report quantifies that risk for the first time, calculating how much it accumulates each year.
此前的一些研究，包括一篇在4月发表的分析报告，也显示了同样的结论，这种风险在35岁时大于25岁，且会随着年龄的增加而同步攀升。这次的新报告则首次将风险量化，计算了风险每年会增加多少。
The research team found that the average child born to a 20-year-old father had 25 random mutations that could be traced to paternal genetic material. The number increased steadily by two mutations a year, reaching 65 mutations for offspring of 40-year-old men.
研究小组发现，一个20岁父亲所生的孩子会携带25个可以追溯到父亲遗传物质的基因突变 。突变的数量每年稳定增加两个，在父亲40岁的新生儿中达到65个。
The average number of mutations coming from the mother’s side was 15, no matter her age, the study found.
研究还发现，来自母亲的平均突变数是15个，无关她的年龄。
“This study provides some of the first solid scientific evidence for a true increase in the condition” of autism, said Dr. Fred R. Volkmar, director of the Child Study Center at the Yale School of Medicine, who was not involved in the research. “It is extremely well done and the sample meticulously characterized.”
“这项研究，首次为自闭症发病率真正的增长原因提供了一些坚实的科学证据。研究做得非常好，对病例特点的分析也极为精细。”耶鲁大学医学院(Yale School of Medicine)儿童研究中心(Child Study Center)主任弗雷德·R·福尔克马尔博士(Fred R. Volkmar) 说，他并没有参与这项研究。
The new investigation, led by the Icelandic firm Decode Genetics, analyzed genetic material taken from blood samples of 78 parent-child trios, focusing on families in which parents with no signs of a mental disorder gave birth to a child who developed autism or schizophrenia. This approach allows scientists to isolate brand-new mutations in the genes of the child that were not present in the parents.
这项新的调查由冰岛的基因解码公司(DeCode Genetics)带领完成，分析了78组父、母、子的血样中遗传物质。研究集中于那些父母没有精神疾病的迹象，生出的孩子却得了自闭症或精神分裂症的家庭。这种方法使科学家可以分离出那些在父母基因中不存在，却在子女基因中发生了的新突变。
Most people have many of these so-called de novo mutations, which occur spontaneously at or near conception, and a majority of them are harmless. But recent studies suggest that there are several such changes that can sharply increase the risk for autism and possibly schizophrenia — and the more a child has, the more likely he or she is by chance to have one of these rare, disabling ones.
大多数人有很多这种所谓的“新生突变”，这些突变在母亲受孕时或孕后不久随机发生，大多数是无害的。但最近有研究显示，某些这样的突变会显著增加患上自闭症，或者是精神分裂症的风险。子女新生突变越多，发生某种罕见的致病突变的几率也就越高。
Some difference between the paternal and maternal side is to be expected. Sperm cells divide every 15 days or so, whereas egg cells are relatively stable, and continual copying inevitably leads to errors, in DNA as in life.
父亲和母亲双方的遗传差异是不难想见的。精子细胞大约每隔15天就进行一次分裂，但卵细胞相对来说比较稳定。而持续不断的复制不可避免地会导致错误，生活中如此，DNA也是一样。
Still, when the researchers removed the effect of paternal age, they found no difference in genetic risk between those who had a diagnosis of autism or schizophrenia and a control group of Icelanders who did not. “It is absolutely stunning that the father’s age accounted for all this added risk, given the possibility of environmental factors and the diversity of the population,” said Dr. Kari Stefansson, the chief executive of Decode and the study’s senior author. “And it’s stunning that so little is contributed by the age of the mother.”
然而，当研究者排除父方年龄的因素后，他们还是发现，那些患有自闭症或精神分裂症的研究对象和作为对照组的正常冰岛人之间，在遗传风险上没有不同。“考虑到环境因素和人口的多样化，所有额外的风险都可以归因于父亲的年龄，这简直太惊人了。”Decode公司的首席执行官以及该研究的高级作者卡里·斯特凡松(Kari Stefansson)说道。“同样令人惊讶的是，母亲年龄造成的影响是这么小。”
In the end, these kinds of mutations may account for 20 to 30 percent of cases of autism, and perhaps schizophrenia, some experts said. The remainder is likely a result of inherited genetic predisposition and environmental factors that are the subjects of numerous studies.
一些专家指出，这类突变最终导致的自闭症或精神分裂症案例占总数的20%到30%。剩下的病因可能是遗传的基因倾向以及环境因素等，已有众多研究以这些因素为课题。
Dr. Stefansson and other experts said that an increase in the average age of fathers had most likely led to more cases of autism. Unlike other theories proposed to explain the increase, like vaccinations, it is backed by evidence that scientists agree is solid.
斯蒂芬森博士和其他专家指出，男性作父亲的平均年龄的增加，极有可能是自闭症患儿增多的原因。和其他用来解释这一现象的理论不同（如疫苗），科学家们同意这一理论有确凿证据的支撑。
But this by itself hardly explains the overall increase in diagnoses, at least in the United States. The birthrate of fathers age 40 and older has increased by more than 30 percent since 1980, according to government figures, but the diagnosis rate has jumped tenfold, to 1 in 88 8-year-olds in the most recent government survey.
但仅靠这种理论不能解释整体上确诊病例数量的增加，至少在美国是这样。政府数据显示，自1980年以来，父亲在40岁及以上的新生儿出生率增加了30%多，但自闭症确诊率却激增10倍，最近的政府调查显示的数据是，每88名8岁儿童中就有一人患病。
And it is not clear whether the rate of schizophrenia diagnosis has increased at all in that time.
还不清楚精神分裂症的确诊率在这段时间内是否有增加。
Nonetheless, if these study findings hold up and extend to other brain disorders, wrote Alexey S. Kondrashov of the University of Michigan, in an editorial accompanying the study, “then collecting the sperm of young adult men and cold-storing it for later use could be a wise individual decision.”
但是，密歇根大学(University of Michigan)的阿列克谢·S·孔德拉绍夫(Alexey S. Kondrashov)在配合这篇论文发表的评论中写道，若这些研究结果成立，并能适用于其他的大脑疾病，“那么收集并冷冻年轻男性的精子以待后用，不失为明智的个人选择。”
That very much depends on the individual, of course. Said Evan E. Eichler, a professor of genome sciences at the University of Washington in Seattle, “You have to understand that the vast majority of these mutations have no consequences, and that there are tons of guys in their 50s who have healthy children.”
当然，这很大程度上取决于个人。西雅图华盛顿大学(University of Washington)的基因组科学教授埃文·E·艾希勒(Evan E. Eichler)说，“你要知道，这些突变绝大部分不会产生什么后果，而且有很多男性在50岁以后生下的孩子也很健康。”