A couple has been given permission to use fertility treatment to create a "saviour sibling" for their seriously-ill 20-month-old daughter.
Charlotte Mariethoz, from Leicester, has a rare blood condition called diamond blackfan anaemia and her only hope is a stem cell transplant from a genetically matched donor.
The Human Fertilisation and Embryology Authority, has issued a licence to a clinic allowing it to use controversial testing techniques to create a "designer baby" who will be a donor for Charlotte.
Embryos created through IVF treatment on her parents will be tested when they are a few days old to find a perfect genetic match. If there is one, the embryo will be implanted in Mrs Mariethoz's womb. When he or she is born, stem cells will be removed from the umbilical cord and transplanted into Charlotte.
Diamond blackfan anaemia affects only 100 children in the UK but sufferers usually die by 30. The condition is not genetic and the embryo tests will ensure the second baby does not have the same condition.
Anti-abortion groups are opposed to preimplantation genetic diagnosis, claiming it could be abused, allowing designer babies to be created on the basis of their eye colour or sex. They are also concerned about the pressure on any "saviour sibling" if the treatment does not save their elder brother or sister.
The Lords ruled last year that the technique could be authorised and a small number of licences has been issued. Last July, Julie and Joe Fletcher were the first UK couple to have a "saviour sibling". Their daughter Jodie was a perfect match for her three-year-old brother Joshua, who has diamond blackfan anaemia.