胚胎基因編輯值得肯定

The first successful “gene editing” of human embryos to prevent transmission of inherited disease, announced this week, is a landmark in biotechnology. Humanity has gained the power to engineer its own evolution by making genetic changes that will be passed down through future generations.

首例爲了防止遺傳疾病傳播而對人類胚胎進行“基因編輯”的成功實驗在本週宣佈，這是生物技術領域的一塊里程碑。人類獲得了設計自身進化的力量——通過將會傳給子孫後代的基因改變。

Most scientists have rightly greeted the achievement, by a US-based team working with colleagues in South Korea and China, as an experimental tour de force. Using new technology called Crispr, the researchers removed a genetic mutation that causes sudden heart failure from dozens of early human embryos with impressive precision and efficiency — and without the “off-target” impact on other genes that many feared would be an unwanted side-effect of gene editing. But much more work will be needed to assess the technique’s safety before anyone plans to implant an edited embryo into a womb.

多數科學家正確地歡迎由一個美國團隊在與韓國和中國同事合作下取得的這項成就，視其爲一個實驗傑作。研究人員利用基因編輯技術CRISPR，以令人印象深刻的精確度和效率，從幾十個早期階段人類胚胎中切除了將會導致突發性心臟衰竭的基因突變，而且沒有對其他基因造成“脫靶”損傷，而很多人曾經擔心這種損傷將是基因編輯的一種不可取的副作用。但是，在任何人計劃將編輯好的胚胎植入子宮之前，還需要進行大量工作，以評估這種基因編輯技術的安全性。

The project’s success should inspire governments, regulatory authorities and medical academies around the world to prepare more actively for clinical trials leading to genetically engineered babies. On top of thorough safety testing, extensive regulatory and ethical work with maximum public involvement will be needed before this can happen — building on the activities of bodies, such as the Nuffield Council on Bioethics in the UK and American Society of Human Genetics, that are already engaging with the subject.

這個項目的成功應該鼓舞世界各國政府、監管機構和醫學院校更積極地準備最終將會帶來“基因工程嬰兒”的臨牀試驗。在臨牀試驗可以啓動之前，除了嚴密的安全測試以外，還需要廣泛的監管和倫理研究，並且讓公衆最大限度地參與討論——以已經在研究這個主題的機構，如英國納菲爾德生物倫理學理事會(Nuffield Council on Bioethics)和美國人類遺傳學會(American Society of Human Genetics)的工作爲基礎。

If we dismiss the idea of an absolute religious or philosophical prohibition of any tampering with human evolution, even to prevent the most horrible diseases, then there are several other issues to consider.

如果我們拒絕以宗教或哲學爲本的絕對禁止對人類進化作任何篡改（哪怕爲了預防最可怕的疾病也不能例外）的觀念，那麼還有其他幾個議題需要考慮。

The “slippery slope” argument — that technology developed for good medical reasons will inevitably be applied for ethically more dubious purposes such as producing “designer babies” with enhanced looks, athletic ability or intelligence — justifies strong regulatory controls to prevent such abuse, but is surely no reason to abandon research that aims to reduce human suffering.

“滑坡”論點——出於良好醫學理由而開發的技術，將不可避免地被應用於在倫理上更爲可疑的目的，例如生產具有增強外表、運動能力或智力的“設計師寶寶”——說明需要強有力的監管控制來防止這種濫用，但這肯定不是放棄旨在減少人類苦難的研究的理由。

In fact there are sound scientific reasons why it would be extremely hard to apply the technology to genetic enhancement. One is that the desired traits depend on many genes acting together, most of them unknown; these will lie far beyond the scope of DNA editing for the foreseeable future. Another is that the experiment published this week worked well because each embryo carrying a defective heart gene also had a healthy copy, which acted as a template for the DNA repair process. This should make Crispr editing possible in thousands of other inherited disorders in which sufferers have one good and one bad copy of the gene responsible. There would be no comparable template for genetic enhancement.

事實上，有充分的科學理由說明，爲什麼將這項技術應用於基因增強是極其困難的。其中一個原因是，想要的特性取決於許多基因的共同作用，其中大多數是未知的；在可預見的未來，這些將遠遠超出DNA編輯的範疇。另一個原因是，本週發表的實驗之所以進行順利，是因爲每一個攜帶有缺陷心臟基因的胚胎都有一個健康的“副本”，後者可作爲DNA修復過程的模板。這種方法應該使CRISPR編輯能夠被應用於數千種其他遺傳疾病——只要患者有一個好版本的基因，也有一個要負責的壞版本基因。對於基因增強，就沒有這種可比較的模板了。

Critics also question the need for gene editing when pre-implantation diagnosis (PGD), which selects healthy IVF embryos by a DNA test, can do the job, too. This is often true, but sometimes no healthy embryos are available — and, even when they are, gene editing could increase the number available to implant in the womb.

當胚胎植入前遺傳學診斷(PGD)——通過DNA測試來選擇健康的體外受精(IVF)胚胎——也可以達到同樣目的時，批評者還質疑基因編輯的必要性。這個命題往往是正確的，但有時沒有健康的胚胎可用——再說即使存在健康的胚胎，基因編輯也可以增加可植入子宮內的胚胎數量。

A more practical barrier to embryonic gene editing may be cost and complexity. The Crispr procedure is bound to be expensive, even after streamlining for clinical use, and PGD will still be needed before implantation to ensure that the DNA has been repaired. The number of beneficiaries may be small in the early years, but the technology’s long-term promise is so great that society must develop a framework for its clinical development. Producing healthy babies is a laudable aim.

胚胎基因編輯的更實際障礙可能是成本和複雜性。CRISPR手術肯定是昂貴的，即使在經過精簡用於臨牀之後也會如此，同時在植入胚胎前仍然需要PGD診斷，以確保DNA已被修復。受益者的數量在初期可能很少，但這種技術的長期前景是如此之大，社會必須爲其臨牀開發制定一個框架。生產健康的寶寶是值得稱道的目標。