Dozens of human embryos with three parents have been created by British scientists, ushering in an era of designer babies. The embryos - which effectively have two mothers and one father - have been genetically engineered to be free from incurable muscle, brain, heart and digestive illnesses, some of which kill within hours of being born. The Newcastle University researchers say that within as little as three years, it could allow women whose families are blighted by disease the chance of bringing a healthy child into the world.
But critics say the breakthrough is a step on the slippery slope towards human cloning and erodes the sanctity of human life. The cutting-edge research centres around mitochondria - sausage-shaped powerhouses inside cells which turn food into energy to be used by the brain and body. Each mitochondrion has is own DNA which gives instructions on how to build and operate the powerpack, or battery, and is passed down from mother to child. Serious defects in this DNA affect one in 6,500 babies and cause around 50 genetic diseases, some of which kill in infancy. With no cure for the conditions, which include some forms of diabetes, blindness and heart problems, women carrying diseased mitochondria often face the heartbreaking choice of whether it would be kinder to remain childless. The scientists have found a way of swopping the diseased DNA with healthy genetic material, creating embryos free of mitochondrial disease.
The 'transplant' technique, which is described in the prestigious journal Nature, begins by using IVF techniques to fertilise an egg from a healthy donor. When the resulting embryo is just a few hours old, the 'pronuclei', or nuclear DNA from the sperm and egg are removed, leaving the healthy mitochondria behind. The would-be mother's egg is then fertilised with her partner's sperm and the pronuclei removed and popped into the donor egg. This creates an egg where the genetic material comes overwhelmingly from the prospective parents and the mitochondria are healthy.
If the method is successful, the disease should be eradicated from future generations of the family. Professor Alison Murdoch, head of the Newcastle Fertility Centre, whose patients donated eggs for the study, said: 'It would be hype to say we are going to get rid of mitochondrial disease but I think it's realistic to say you could get rid of it in an individual family.' Eighty embryos were created in the Newcastle labs, each effectively with three parents - two mothers and a father. A fourth parent - the man whose sperm was used to fertilise the donor egg - was involved, but none of his DNA was passed on. Some of the embryos lived for six days, before they were destroyed to comply with fertility laws, which also forbid such embryos from being implanted in a woman.
But updated fertility laws which came into effect last year leave the door open for the legislation to be amended, allowing the technique women to give birth to disease-free babies. Lead researcher Professor Doug Turnbull said that if this happened, the first babies could be born in as little as three years. 'What we've done is like changing the battery on a laptop,' said the professor, an expert on mitochondrial disease. 'The energy supply now works properly, but none of the information on the hard drive has been changed. 'A child born using this method would have correctly functioning mitochondria, but in every other respect would get all their genetic information from their father and mother.
'This is a very exciting development with immense potential to help families at risk from mitochondrial diseases. 'We have no way of curing these diseases at the moment, but this technique could allow us to prevent the diseases occurring in the first place. 'It is important that we do all we can to help these families and give them the chance to have healthy children, something most of us take for granted.' Sir Mark Walport, director of the Wellcome Trust, which helped fund the research, said: 'This is exciting research that could lead to the major clinical advance of preventing devastating mitochondrial diseases by curing the disease in fertilised eggs.'
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