There are benefits to having three parents. You get to decide whether they are enough

In October I wrote an article in The Economist on a new method for curing mitochondrial disease. The method involves replacing faulty DNA from a mother’s egg with that from a healthy donor. And, if the baby is born, in principle, it paves way for a child to have three genetic parents.

Despite the public “uggh” factor raised by the idea of a three-parent child raises, there are good reasons for having such offspring. The technique may help cure a set of rare but nasty, inheritable diseases caused by faulty DNA our cells, and after decades of work researchers have developed a way of replacing those faulty bits.

Currently the law in Britain prohibits this vital research needed to develop a cure, because the process involves tinkering with human DNA. While such tinkering raises a number of issues, in this case, it should not stop that research from going forward. As I argued in the editorial that accompanied the article:

Mitochondrial transplants involve no tinkering with the DNA itself. Though on a microscopic scale, the process is quite like a heart, liver or kidney transplant, with the caveat that the transplant will be passed on to the recipient’s children, if she is female. Any organ transplant introduces new genes into the body. Mitochondrial genes are ubiquitous, it is true, but this difference is one of degree, not kind.

Another reason not to worry is that the mitochondria carry only 37 genes, compared with about 20,000 in the cell nucleus, and these genes are exclusively concerned with energy metabolism. Pushy parents will not be picking mitochondrial donors on the basis of looks, personality or intelligence.

Non-biological objections are sometimes raised as well. Some worry, for instance, that a person with three genetic parents might suffer an identity crisis. But that seems less likely than in the case of people conceived by in vitro fertilisation using sperm donated by strangers who have contributed half of their offspring’s genes, not a paltry three dozen. And for that reason mitochondrial donors are even less likely than sperm donors to want to be involved with bringing up children in whom they have but a fractional genetic interest.

The Human Fertilisation and Embryology Authority (HFEA) ends its consultation on mitochondrial replacement therapy today. Please take a few minutes to fill up the survey.

Your decision in the consultation is not to decide whether or not to allow this therapy to be used in public today, but to decide whether or not to allow the research to test for the therapy’s safety and efficacy.

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