British lawmakers have given the thumbs up to a fertility treatment that uses genetic material from three people. The first birth to result from the mitochondrial treatment may come as early as next year.

As we’ve previously detailed, the treatment aims to prevent mothers passing on disorders that results from faults in mitochondria, the “power plants” of cells.

The treatment takes advantage of the fact that mitochondria (#9 in the picture) is located outside the nucleus in a cell. The treatment involves creating two embryos, one from the mother and father’s egg and sperm and the second from the father’s sperm and a donor’s egg. The nucleus from the donor embryo is then replaced with the one from the parent embryo.

Previous ethics reviews have concluded that the description of a “baby with three parents” is inaccurate. That’s because the proportion of the baby’s genome that would come from the donor would be approximately 0.001 percent, and that none of this would involve inherited traits.

The proposed law to allow such treatment makes clear that the donor would not be considered as a relative of the baby. It also restricts the treatment to cases where not only is there a serious likelihood of a genetic disorder being inherited, but where that disorder would also pose a serious risk to the child. Only licensed providers will be allowed to carry out the treatment, which is initially expected to be restricted to the University of Newcastle.

Members of the elected House of Commons today backed the proposed law by 382 votes to 128. It was judged an issue of conscience and thus the politicians did not have to follow party instructions on how to vote.

While many politicians spoke in favor of the technique, some argued that the results were too uncertain. Some religious figures have argued that it is wrong to produce embryos with the intention that they be destroyed.

The proposals will now need to pass a vote in the unelected House of Lords to become law. It’s uncertain if that will happen, but if they did reject it, the House of Commons could hold a fresh vote 12 months later which, if passed, would automatically turn it into law.