The aim of this form of IVF is to stamp out serious diseases which can be passed from a mother to her children. Around one in 200 babies are born each year in the UK with a defect in the way cells are supplied with energy.
One in 6,500 babies can suffer potentially life-threatening diseases including a form of muscular dystrophy and conditions leading to hearing and vision loss, heart, lung and liver problems, and bowel disorders. An estimated 12,000 people in the UK live with the diseases.
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Gordon Brown has said forced child migration schemes that continued until the 1970s amounted to "government-induced trafficking".
200 UK officers already working on the case are sifting through 15 tonnes of debris on each of the building's 24 floors.