超级富豪也将成为健康超人

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　　如果说人类基因组是生命之书，那么Crispr技术就是用来编写这本书的Microsoft Word。这种基因“剪切和粘贴”技术3年前才问世，可用于从初露端倪的基因组中剪除DNA片段，如有需要，还可向基因组中插入新的片段。

　　The amendments³ are permanent and can be passed down the generations. The technology works on mice and men; a team in China recently revealed they had partially⁵ succeeded in excising⁶ the gene⁴ for beta thalassaemia, an inherited blood disorder⁷, from a human embryo⁸. It is a wonder society is not yet spooked by what could be a defining technology for the future of humanity.

　　这种修改是永久性的，可以代代相传。这种技术可以用于小鼠和人类；中国的一个科研小组最近透露，他们从一个人类胚胎上切除β-地中海贫血症（一种遗传性血液疾病）基因的操作取得了部分成功。奇怪的是，这种可能界定人类未来的技术还未震惊社会。

　　超级富豪也将成为健康超人

　　Crispr — short for clustered regularly interspaced short palindromic repeats — is the simplest of a suite⁹ of new gene-editing technologies, and is a trick borrowed from the bacterial¹⁰ immune system. Bacteria, when invaded by a virus, deploy¹¹ “molecular scissors” — a DNA-cutting enzyme¹² that chops up the invader¹³. Pair the scissors with a guiding molecule¹⁴ capable of directing the blades to a specific point, and you are ready to edit a genome. After the DNA is severed¹⁵, cellular¹⁶ repair machinery¹⁷ kicks in to close the gap and the embryo continues to develop. This is how the Chinese scientists banished¹⁸ the mutant gene from their human embryo.

　　Crispr是“规律成簇的间隔短回文重复”(clustered regularly interspaced short palindromic repeats)的简称，是一套新的基因编辑技术中最简单的一种，借鉴了细菌的免疫系统。当细菌遭到病毒的入侵时，会使用“分子剪刀”——一种DNA内切酶来切掉入侵者。将分子剪刀与一个能将“刀锋”引导到特定点的分子进行配对，你就能够对基因组进行编辑了。DNA被切除后，细胞修复机制开始发挥作用，接合断裂的部分，胚胎继续发育。这就是中国科学家从人类胚胎中去除突变基因的方法。

　　The deletion was not perfect. It was carried out in a non-viable embryo so we will never know if it would have developed into a thalassaemia-free baby. Nonetheless, the research was so controversial that both Nature and Science declined to publish it. But publication elsewhere in April ignited a debate that still burns. A group of mostly US biologists has called for a moratorium¹⁹, noting that modifications²⁰ to the human germ line (changes that would be passed down generations) constituted a Rubicon not to be crossed lightly. UK scientists, working in a tight regulatory regime, are loath²¹ to back this call given the risk to basic science.

　　这一切除还不完美。由于实验是在一个不能存活的胚胎上进行的，我们永远无从得知这个胚胎能否发育成一个不会患地中海贫血症的婴儿。尽管如此，这项研究极富争议性，以至于《自然》(Nature)和《科学》(Science)都拒绝发表这项研究。但该研究今年4月发表在别处，引发了一场仍在激烈展开的辩论。以美国生物学家为主的一组科学家呼吁中止研究，指出对人类生殖细胞系的修改（这种修改会代代相传）是一条不可轻率跨过的界线。在严格的监管制度下工作的英国科学家考虑到对基础科学构成的风险，不愿呼应前者的呼吁。

　　This reluctance²² to impede²³ fundamental research is shared by Jennifer Doudna of University of California, Berkeley, who co-invented Crispr and won a $3m Breakthrough prize last year (she is also tipped for a Nobel). US politicians, however, are twitchy; a proposal being considered in Congress would ban the Food and Drug Administration from approving clinical applications in human embryos²⁴.

　　美国加州大学伯克利分校(University of California, Berkeley)的珍妮弗?杜德纳(Jennifer Doudna)也不太情愿阻碍基础研究，她是Crispr技术的发明者之一，去年赢得了300万美元的“突破奖”(Breakthrough Prize)（很多人认为她还将获得诺贝尔奖）。然而，美国政界人士焦虑不安；国会正在考虑一项禁止美国食品药品监督管理局(FDA)批准人类胚胎相关临床应用的法案。

　　The cancellation²⁵ of human disease at genome level, which affects an individual and all their descendants, requires contemplation beyond the laboratory — by philosophers, lawyers, clerics and the public. This has been absent. In the UK there has been febrile discussion over the prospect²⁶ of creating “three-parent babies”using donated mitochondrial DNA; but genome editing could be capable of far greater things, and affects nuclear DNA — from which we derive²⁷ our genetic²⁸ identity.

　　在基因组层面消除人类疾病，将影响个人及其所有后代，这需要实验室以外的社会各界进行考量——哲学家、律师、宗教人士和公众。而这些人现在缺席。在英国，人们正在热烈讨论使用捐献的线粒体DNA生育“三亲婴儿”的前景；但基因组编辑能够做到更加伟大的事情，它会影响我们获得遗传特征的来源——核DNA。

　　Inserting new genes²⁹, which has yet to be carried out in human embryos, raises further questions. If, in one embryo, I paste in a royal flush of genes conferring resistance to Ebola, cancer and Alzheimer’s, have I created a superhuman? Will perfect health become the preserve of the super-rich? Start-ups such as Editas Medicine of the US are already gambling³⁰ on this. We may one day have unaltered people living alongside a younger, gene-edited generation.

　　目前新基因插入还未在人类胚胎上进行过，这种技术提出了更多问题。如果我向一个胚胎插入一套基因，使其获得对埃博拉、癌症和阿尔茨海默病的抗性，我是否创造了一个超人？完美的健康会不会成为超级富豪的专属？美国的Editas Medicine等初创公司已经启动这场豪赌。有一天，未曾进行基因修改的人或许会和更年轻、进行过基因编辑的一代人共同生活在一个世界上。

　　That the discussion has not gone fully³¹ public might be because genome- editing technology is complex — and because, un?like with mitochondrial disease, there are no heart-wrenching personal tales on which to hang the debate. The Nuffield Council on Bioethics, a UK-based charity, is considering genome-editing; its views cannot come too soon.

　　这场讨论还未完全公开，或许是因为基因编辑技术比较复杂，也可能是因为不像线粒体疾病的相关技术，这场辩论无法用催人泪下的个人故事大做文章。英国慈善机构纳菲尔德生命伦理委员会(Nuffield Council on Bioethics)正在考虑基因组编辑；该委员会的意见让人期待。

　　Imagining ourselves as glorified³² books, penned in the language of genes, is a fitting analogy as we muddle³³ on. At some point, society must decide whether any person deserves to be a perfect piece of prose, or whether we should each remain an unedited thriller³⁴ with an unpredictable ending.

　　在我们继续摸索之际，一个合适的类比是把我们自己想象成一本用基因语言书写的精彩的书。在某个时间点，社会必须决定，是不是有任何人应该成为一篇完美的散文，还是该保持现状，继续做一篇未经编辑的、结尾不可预测的惊险小说？

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