試管嬰兒新技術：一些試管嬰兒還具有父母之外第三人的遺傳信息

——梁詩豪／文 來源：微信公眾號種下希望（re-preg）

編者的話：

各位朋友，你知道試管嬰兒嗎？那是利用人為的方法讓精子卵子在體外融合發育成胚胎再植入回子宮的技術。通常所說的試管嬰兒是父母精子卵子的結合體，但你聽說過嗎？有的嬰兒還可以有除了父母之外第三者的遺傳信息。

Exclusive:World』s first baby born with new 「3 parent」 technique

獨家：第一個使用新「三父母」技術出生的嬰兒

By Jessica Hamzelou

由Jessica Hamzelou 攥寫

It』s a boy! A five-month-old boy is the first baby to be born using a new technique that incorporates DNA from three people, New Scientist can reveal. 「This is great news and a huge deal,」 says Dusko Ilic at King』s College London, who wasn』t involved in the work. 「It』s revolutionary.」

是個男孩！New Scientist 雜誌揭示，這個男嬰已經五個月大了，是第一個使用新技術出生的嬰兒，男嬰整合了3人的DNA信息。倫敦King』s大學的Dusko Ilic說：「這是個好消息而且具有很大的意義，是具有革命性的。」

The controversial technique, which allows parents with rare genetic mutations to have healthy babies, has only been legally approved in the UK. But the birth of the child, whose Jordanian parents were treated by a US-based team in Mexico, should fast-forward progress around the world, say embryologists.

這個具有爭議性的技術，允許攜帶稀少變異基因的家長獲得健康的BABY，目前全世界只有英國立法同意。但是胚胎學家說這對家長的這件案例應該會加快這項技術在世界的普及以及接受進度。

The boy』s mother carries genes for Leigh syndrome, a fatal disorder that affects the developing nervous system. Genes for the disease reside in DNA in the mitochondria, which provide energy for our cells and carry just 37 genes that are passed down to us from our mothers. This is separate from the majority of our DNA, which is housed in each cell』s nucleus.

男孩的媽媽有造成Leigh氏腦病的基因，這種病症是一種致死性紊亂，會影響到神經系統的發育。致病基因潛藏在線粒體的DNA中。線粒體為機體提供能量而且攜帶有37個來自母體的基因。這與我們的主要的DNA不同，主要DNA在細胞核中。

Around a quarter of her mitochondria have the disease-causing mutation. While she is healthy, Leigh syndrome was responsible for the deaths of her first two children. The couple sought out the help of John Zhang and his team at the New Hope Fertility Center in New York City.

患者大約有1/4的線粒體有致病基因。雖然她是健康人，Leigh氏腦病與她前兩個孩子的死亡都有關。夫婦找到新希望生殖中心的張進團隊尋求幫助。

Zhang has been working on a way to avoid mitochondrial disease using a so-called 「three-parent」 technique. In theory, there are a few ways of doing this. The method approved in the UK is called pronuclear transfer and involves fertilising both the mother』s egg and a donor egg with the father』s sperm. Before the fertilised eggs start dividing into early-stage embryos, each nucleus is removed. The nucleus from the donor』s fertilised egg is discarded and replaced by that from the mother』s fertilised egg.

張一直致力於使用所謂的「三父母」技術來避免線粒體疾病。從理論上來講，有幾種方法可以做到避免這種疾病。該方法在英國受到批准，被稱為原核移植，並涉及到用父親的精子來使母親和捐獻者的卵子受精。在兩個受精卵開始分裂形成早期胚胎之前，每個的細胞核都被去掉。把捐贈者的受精卵核丟棄，取而代之的是母親方來的的受精卵核。

But this technique wasn』t appropriate for the couple – as Muslims, they were opposed to the destruction of two embryos. So Zhang took a different approach, called spindle nuclear transfer. He removed the nucleus from one of the mother』s eggs and inserted it into a donor egg that had had its own nucleus removed. The resulting egg – with nuclear DNA from the mother and mitochondrial DNA from a donor – was then fertilised with the father』s sperm.

但這種技術不適合這對夫婦，他們是穆斯林。穆斯林反對對於兩個已經形成的胚胎的破壞。因此張的團隊採取了一種不同的方法，被稱為spindle nuclear transfer。具體做法是從母親方的卵子中取出細胞核，將其注入到一個已經去核的供者卵中。由此產生的卵子既攜帶有供者線粒體DNA也有母親的主要DNA，最後被父親的精子受精。

Zhang』s team used this approach to create five embryos, only one of which developed normally. This embryo was implanted in the mother and the child was born nine months later. 「It』s exciting news,」 says Bert Smeets at Maastricht University in the Netherlands. The team will describe the findings at the American Society for Reproductive Medicine』s Scientific Congress in Salt Lake City in October.

張的團隊使用這種方法創造了五個胚胎，只有其中一個發育正常。這個胚胎被移植到母親子宮，孩子在九個月後出生。在荷蘭Maastricht大學的Bert Smeetss說「這是令人振奮的消息。」該小組將在十月在鹽湖城的美國生殖醫學科學大會上報告自己的發現。

Neither method has been approved in the US, so Zhang went to Mexico instead, where he says 「there are no rules」. He is adamant that he made the right choice. 「To save lives is the ethical thing to do,」 he says.

這兩種方法在美國都沒有被批准，所以張去了墨西哥，他說：「這裡沒有規則」。他堅決的說他做了正確的選擇。他說：「拯救生命是一件有道德的事。」

The team seems to have taken an ethical approach with their technique, says Sian Harding, who reviewed the ethics of the UK procedure. The team avoided destroying embryos, and used a male embryo, so that the resulting child wouldn』t pass on any inherited mitochondrial DNA. 「It』s as good as or better than what we』ll do in the UK,」 says Harding.

Sian Harding說：「張團隊似乎通過他們的技術使用了有道德的途徑去解決問題。」他回顧了英國輔助生殖程序中的倫理。該小組避免破壞胚胎，並使用了一個雄性胚胎，使所得到的孩子不會傳遞任何遺傳的線粒體DNA給下一代。Harding說：「這次治療和我們在英國所能做的一樣好或更好。」

A remaining concern is safety. Last time embryologists tried to create a baby using DNA from three people was in the 1990s, when they injected mitochondrial DNA from a donor into another woman』s egg, along with sperm from her partner. Two of the fetuses developed genetic disorders, and the technique was halted by the US Food and Drug Administration. The problem may have arisen from the fetuses having mitochondria from two sources.

剩下的擔憂是安全方面的。上次胚胎學家試圖利用三人的DNA創造一個嬰兒是在上世紀90年代。在那時，他們將從供體卵子獲得的線粒體DNA，注射到母方的卵子。而後注射的是的她的伴侶的精子。兩個胎兒發育時都出現了基因紊亂。該技術隨後被美國食品和藥物管理局（FDA）叫停。這一問題可能是由於胎兒同時擁有兩個來源的線粒體產生的。

When Zhang and his colleagues tested the boy』s mitochondria, they found that less than 1 per cent carry the mutation. Hopefully, this is too low to cause any problems; generally it is thought to take around 18 per cent of mitochondria to be affected before problems start. 「It』s very good,」 says Ilic.

當張和他的同事們測試了這個男孩的線粒體時，他們發現，不到1％的線粒體攜帶這種突變。寄希望來講，這個值太低，很難造成任何問題，一般認為在問題開始出現之前，需達到約18 %的線粒體突變。伊利奇說：「這是非常好的。」

Smeets agrees, but cautions that the team should monitor the child to make sure the levels stay low. There』s a chance that faulty mitochondria could be better at replicating, and gradually increase in number, he says. 「We need to wait for more births, and to carefully judge them,」 says Smeets.

Smeets先生同意，但警示的說，張團隊應該嚴密監控孩子去確保突變線粒體保持在低水平。有這麼一種機會，有缺陷的線粒體可能有更強的複製能力，然後數量逐漸增加並佔領細胞。他說。「我們需要等待更多的嬰兒出生，並仔細觀察與判斷他們（來總結出更多經驗規律）。」(河南省人民醫院生殖研究所）