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没有证据表明在胚胎选择中使用多基因风险评分法

  一些私人生育诊所宣传和推销在胚胎选择中使用多基因风险评分(PRS)。

  这些诊所声称,胚胎的PRS可以帮助预测未来孩子患上某些疾病或复杂特征的可能性,这些疾病或特征被认为是受一些不同基因的影响。然而,发表在《欧洲人类遗传学杂志》上的一篇论文说,没有证据表明PRS能够以这种方式可靠地预测个人的性状。本文认为,使用PRS来选择胚胎是未经证实的,也是不道德的。

  "第一作者、欧洲人类遗传学会(ESHG)公共和专业政策委员会主席Francesca Forzano博士说:"许多疾病是由遗传和环境共同造成的,而PRS只能捕捉到相关遗传成分的一小部分,这些成分本身可能是非常复杂和难以分析的。"此外,虽然PRS可以识别一般人群中存在某些疾病风险的个体(遗传变异性非常高),但没有证据表明它们可以帮助一对夫妇选择一个胚胎而不是另一个,因为单个家庭中的遗传变异性是有限的。

  个人有不同的特定基因变体。PRS研究可能影响疾病或性状发展的几个基因的变异。一些变体可能会增加发展某种特定性状的可能性,而其他变体则可能会降低这种可能性。

  一个特定个体的特定性状的PRS是基于我们目前对特定人群中遗传变异的了解,然后预测该个体在整个人群中该性状分布的可能位置。[例如,如果有问题的性状是身高,PRS可能会预测该个体是否可能处于人口中最大的20%,最小的20%,或处于中间的某个位置)。

  英国的生育机构--人类受精和胚胎学管理局(HFEA)告诉《泰晤士报》:"在植入前遗传学测试中使用PRS目前在英国是非法的。胚胎选择在英国是合法的,只是为了防止严重的遗传性疾病。

  出版BioNews的慈善机构Progress Educational Trust的主任Sarah Norcross呼吁监管机构密切关注这些测试在英国的营销。"她说:"使用PRS选择胚胎在科学上和伦理上都是不允许的。"即使PRS--尽管完全缺乏临床证据--可以有效地预测某些胚胎的某些事情,但使用该测试所需的胚胎数量无法在临床环境中完成。在生育治疗方面,可供选择的胚胎非常少,所以选择一个胚胎而不是另一个胚胎的理由必须基于明确的证据。

  原来的文章内容如下。

  Some private fertility clinics are promoting and marketing the use of polygenic risk scores [PRSs] for embryo selection.

  These clinics claim that PRSs of embryos can help predict the likelihood of a future child developing certain diseases or complex traits that are thought to be influenced by a number of different genes. However, a paper published in the European Journal of Human Genetics states that there is no evidence that PRSs can reliably predict a person's traits in this way.

  Dr. Francesca Forzano, first author of the paper and chair of the European Society of Human Genetics [ESHG] Public and Professional Policy Committee, said, "Many diseases are caused by a combination of genetics and environment, and PRSs can capture only a fraction of the relevant genetic component, which itself can be very complex and difficult to analyze. In addition, while PRSs can identify the risk of a particular disease in the general population [where genetic variability is very broad], there is no evidence that they are useful to couples in deciding whether to select one embryo or another, because the genetic variability in an average family is limited.

  Individuals have different gene-specific variants. PRSs study variants in multiple genes that can affect the development of a disease or trait, and certain variants may increase the likelihood of developing a specific trait, while others may decrease the likelihood.

  A PRS for a given trait in a given individual is based on what we currently know about genetic variants in a given population of people, and then predicts where the individual is likely to lie in the distribution of the trait across the population. [For example, if the trait in question is height, the PRS might predict whether the individual is likely to be in the largest 20 percent of the population, the smallest 20 percent of the population, or somewhere in the middle].

  The U.K.'s fertility regulator, the Human Fertilisation and Embryology Authority [HFEA], told The Times, "The use of PRS in preimplantation genetic testing is currently illegal in the U.K. Embryo selection is only legal in the UK to prevent serious inherited diseases.

  Sarah Norcross, director of the charity Progress Educational Trust, which publishes BioNews, urged regulators to keep a watchful eye on the marketing of these tests in the United Kingdom. "It is neither scientifically nor ethically legitimate to try to select embryos with PRS," she said. Even if-for the sake of argument and despite the complete lack of clinical evidence-PRS could meaningfully predict certain things about certain embryos, the sheer number of embryos required to use this test would be unachievable in a clinical setting.1 In the context of fertility treatment, there are very few embryos to choose from, so the rationale for favoring one embryo over another must be based on clear evidence.