一个孩子拥有两个母亲？

A team of scientists in Britain were granted official approval to create a human embryo¹ using genetic² material from two women, raising the future prospect³ of babies with a pair of mothers.

The group from Newcastle University has been given the green light by the Human Fertilisation and Embryology Authority (HFEA), the government-appointed genetics and reproductive technology watchdogs for Britain, where such science is tightly regulated.

The scientists will transfer the pro-nuclei -- the components⁴ of a human embryo nucleus⁵ -- made by one man and woman into an unfertilised egg from another woman.

This technique is intended to help prevent mothers from passing on so-called mitochondrial diseases on to their unborn babies, genetic conditions caused by DNA⁶ outside the nucleus of a cell, in the mitochondria.

Mitochondria have their own DNA, inherited from the mother only. If this DNA is faulty, then children can develop diseases affecting cells in the brain, heart, liver, kidney or skeletal muscles, for which there is currently no known cure.

Previous studies in mice showed in was possible to prevent the transmission of mitochondrial disease by moving the nucleus from an egg containing bad mitochondrial DNA to an unaffected egg.

The human trial will not see any eggs allowed to develop into babies, but the research nonetheless remains⁷ controversial.

Professor John Burn from Newcastle University stressed that the new tests would not lead to "designer babies".

"From a philosophical⁸ or medical point of view there is no reason why we should not do this," he said.

"I would use the analogy of simply replacing the battery in a pocket radio to explain what we are doing. You are not altering the radio at all -- just giving it a new power source.

If a baby was born following such a technique, he noted⁹, it would resemble its biological parents rather than the women into whose embryo the nucleus would be transplanted, as characteristics such as hair colour, height and personality come from nucleus DNA.

However, campaigners expressed concern at the project.

"This shows once again that the HFEA does not have any regard for public consultation¹⁰ and the views of the public," Josephine Quintavalle, from the Comment on Reproductive Ethics¹¹ group, told the BBC. 

　　日前一个英国科学家小组得到了有关部门的正式批准，允许他们利用从两名女性身上获取的遗传材料培育人类胚胎。这样在将来的某一天，一个孩子可能就会同时拥有两位生物学意义上的母亲。

　　据法新社9月8日报道，来自英国纽卡斯尔大学的一个研究小组日前得到了英国人类生育及胚胎繁殖管理局（HFEA）的准许，得以开展这项研究。而在通常情况下，此类研究都是被严加限制的。

　　科学家们将把取自于一男一女受精卵的原核（pronuclei，人类胚胎细胞核的构成成分）移植到另外一名妇女提供的一个未受精的卵子中去。这一技术旨在帮助那些患有由线粒体引起的遗传性疾病的母亲们防止将疾病传给她们未出生的胎儿。

　　报道说，胎儿的线粒体拥有其自己的DNA，这只是从其母亲身上遗传而来的。但如果这个DNA具有缺陷，那么孩子在以后的成长过程中则会受到影响脑细胞、心脏、肝脏、肾脏或者骨骼肌的疾病的困扰。而对于这种线粒体疾病，目前人们尚未找到合适的治疗方法。

　　以前在白鼠身上进行的相关研究曾显示，通过将细胞核从含有不良线粒体DNA的卵细胞中移植到另外一个未受精的卵细胞中，以防止线粒体疾病向下一代传递是可能的。

　　虽然，人类试验将不会允许任何卵细胞发育成为小婴儿，但这一研究仍然存在着争议。对此，该大学的约翰·波恩教授也强调说，最新试验将不会导致“设计婴儿”的产生。他说， “我可以用一个类比来解释我们正在从事的这件事，我们只是简单地换掉了一个收音机的电池，并没有改变整个收音机——我们只是给它新的动力来源而已”。

　　波恩教授还表示，如果一个婴儿在这种技术下诞生，他将类似于他的生物学父母，而非那位提供卵子的女性。这是由于胎儿的头发颜色、身高及性格等特征都是来自于受精卵细胞核DNA的。

　　相关：人类绝大多数的遗传基因都是在细胞核内的染色体中，但是在细胞核以外的线粒体中，也存在着含有极少数遗传基因的物质，这些物质被称为是染色体外遗传物质，它是通过母亲遗传的。尽管胎儿所接受的来自线粒体的遗传物质不到1%，但是它们一旦有缺陷，很可能导致50多种遗传性疾病传给胎儿。