- Wednesday, 04 February 2015 15:31
- By: Tom Solomon, The Guardian
John had mitochondrial disease. His mother, who had given him so much in life, had also given him bad mitochondrial DNA. And so he had died. The news that MPs have voted to allow “three-person IVF” babies to prevent some mitochondrial diseases will be welcomed by all those who care for such patients, as well as their families.
Mitochondria are an essential part of the body’s makeup. They are like little batteries inside almost every cell in the body, giving it energy. But when they go wrong they can cause a range of problems. Depending on which tissues in the body are most affected, this might be fits, diabetes, blindness, muscle wasting, heart disease, deafness, dementia – pretty much anything you can imagine. After the House of Commons vote, such diseases will be less likely, which can only be a positive step.
Mitochondrial diseases were first described in the 1960s, and in the 1980s scientists worked out that it was abnormal DNA in mitochondria that was the cause. Almost every cell in the body has in its nucleus DNA – the genetic code that comes from your mother and father. This determines your hair colour, height, everything that makes you what you are. In addition, there is DNA in the mitochondria that comes from your mother only. It doesn’t determine anything important, only whether your cells have energy and, if the mitochondria are faulty, whether you develop a terrible disease. Why the mitochondria carry their own DNA is not known, but probably relates back to the origins of life itself.
In the 1980s, when all this was being worked out, I was a medical student seeing patients with devastating conditions we barely understood. Now, 30 years later, I am a professor of neurology and we know a lot more. Every week in clinic I see patients with a range of other neurological diseases – Parkinson’s, multiple sclerosis, motor neurone disease – for which we have little idea what the cause is.
Although we have treatments to alleviate some of the symptoms, there is no cure for these diseases, let alone something to stop them happening in the first place. But mitochondrial diseases are a different story. Not only have we pinpointed the cause, down to the exact mutations in DNA, but we can stop the disease occurring.
This is a tremendous advance. Day after day we read of scientific breakthroughs that will take decades to develop into a cure. For mitochondrial disease, major breakthroughs occurred in the 1980s; decades later, here we are with a cure for it and it would be folly not to use it.
I find it mind-boggling that anyone would not support this fantastic advance in medical science that means so much to the families affected. It has been carefully developed with detailed scientific and ethical review at every stage: three reviews by the Human Fertilisation and Embryology Authority, a public consultation and a review by the Nuffield Council on Bioethics.
The procedure involves swapping less than one-tenth of 1% of the human genome. But would it matter if it were 1%? Or even 5%? This is DNA that doesn’t determine any human traits, just disease. The naysayers predictably argued that this may be the start of a slippery slope: the next thing might be swapping DNA from the nucleus, rather than the mitochondria. But if that small piece of rogue genome was causing another disease, say, cystic fibrosis, would it be so terrible to swap it?
Those arguing against the procedure seem to be horrified by the thought of babies produced from the DNA of three people. I don’t understand why. My children have the DNA of four people – including their grandparents – and it doesn’t seem to have done them any harm. There is talk of risks of designer babies. After yesterday’s vote, the only designer babies I foresee are those designed without terrible mitochondrial diseases.
In the past few days, we have heard a lot from the families of those affected and how much this ruling means to them. But think also of doctors and other healthcare workers. How would we feel looking after patients such as John in the future if we knew that his devastating illness could have been prevented, but was not?
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