建议通过植入前基因检测来预测常见疾病的风险

建议通过植入前基因检测来预测常见疾病的风险：Preimplantation genetic testing proposed to predict risk of common dis

一项新的研究声称已经绘制了IVF产生的胚胎基因组图，并表明所使用的相同技术也可用于实现植入前基因检测(PGT)。

该论文发表在《自然医学》杂志上，概述了使用微量遗传物质推断3天和5天大的体外胚胎全基因组序列的分子和统计技术。作者认为，这使得预测患癌症和糖尿病等受许多不同基因影响的常见疾病的风险成为可能。这种理解许多基因的综合影响的方法称为多基因风险评分（PRS）。

来自加利福尼亚基因组学公司MyOme的作者写道：“我们的方法能够预测胚胎基因组中罕见和常见的变异。”“我们的研究结果可能会为讨论基于基因组的PGT在临床实践中的效用和实施提供信息。”

为了构建100多个胚胎的基因组，研究人员在称为基因分型的过程中分析了整个基因组中的数十万个特定位点。他们用来自未来父母的基因序列填补了基因组的空白，并将他们预测的基因组与出生的孩子的基因组进行了比较。

作者发现，他们能够以97-99%的准确率推断出用于计算12种医疗状况的PRS的站点的正确序列。他们说这可以为胚胎创建PRS。

虽然组装胚胎基因组的方法引起了科学界的兴趣，但所谓的“PGT-P”（涉及PGS的PGT）的预测价值和伦理意义是有争议的。除论文外，《自然医学》发表评论指出PGT-P存在的许多科学和伦理问题，同时在《自然》杂志上发表了类似的批评性社论。

“需要强调的是，这项研究并未阐明使用PRS进行IVF胚胎选择的最重要方面，其中存在PRS在这种情况下的统计有效性以及程序的伦理适当性的基本问题'，没有参与这项研究的欧洲分子生物学实验室副主任Ewan Birney教授说。

在英国，仅允许有可能生育患有严重遗传疾病（如亨廷顿病或囊性纤维化）孩子的夫妇根据其携带的基因选择胚胎。人类受精和胚胎学管理局最近表示，在英国使用PGT-P进行胚胎选择是不合法的。

原文：

A new study claims to have mapped the genomes of embryos created by IVF，and suggests that the same techniques used could also be used to enable preimplantation genetic testing(PGT).

The paper，published in Nature Medicine，outlines molecular and statistical techniques for inferring the whole genome sequence of three-and five-day-old in vitro embryos using tiny amounts of genetic material.The authors believe that this makes it possible to forecast the risk of developing common diseases，such as cancer and diabetes，that are affected by many different genes.Such an approach to understanding the combined effects of many genes is called a polygenic risk score(PRS).

'Our approach enabled the prediction of both rare and common variants in embryo genomes'wrote the authors，from genomics company MyOme in California.'Our findings may inform the discussion of utility and implementation of genome-based PGT in clinical practice.'

To construct the genomes of more than 100 embryos，the researchers analysed hundreds of thousands of specific sites across the genome，in a process called genotyping.They filled in the gaps in the genomes with genetic sequences from the prospective parents，and compared their predicted genome to that of the born child.

The authors found that they were able，with 97-99 percent accuracy，to infer the correct sequence at sites used to calculate PRSs for 12 medical conditions.They say that this could enable the creation of PRSs for embryos.

While the method for assembling the genomes of embryos is of interest to the scientific community，the predictive value and ethical implications of so-called'PGT-P'(PGT that involves PGSs)are controversial.Alongside the paper，Nature Medicine published commentaries pointing to the many scientific and ethical problems with PGT-P，while a similarly critical editorial on the matter was published in Nature proper.

'It is important to stress that this study does not shed light on the most important aspect of using PRSs for embryo selection from IVF，where there are fundamental questions of both the statistical validity of the PRS in this setting and also the ethical appropriateness of procedure'，said Professor Ewan Birney，deputy director of the European Molecular Biology Laboratory，who was not involved in the study.

In the UK，selecting an embryo based on the genes it carries is only permitted for couples who are at risk of having a child with a serious genetic condition，such as Huntington's disease or cystic fibrosis.The Human Fertilisation and Embryology Authority has recently stated that it would not be legal to use PGT-P for embryo selection in the UK.