Instead of choosing an embryo based on eye-color or other traits, this couple chose to carry an embryo based on the fact that it could save the life of their other child. This marks the first time that parents have used genetic testing to select a child who is both free of a disease and is the best tissue match for a sibling who needs a transplant to fight that disease. Molly Nash was born with an inherited bone marrow disease called Fanconi anaemia which kills sufferers before the age of seven. To save her life, doctors needed to transplant cells from a perfectly matched sibling. The deadly condition prevents Molly Nash from creating her own bone marrow and could lead to leukemia.
Children suffer from severe bleeding and immune system disorders.
But, in this case, doctors also selected an embryo which would produce the tissue match necessary to offer Molly the chance of a bone marrow transplant. On 26 September at Fairview-University Medical Center in Minneapolis, doctors took stem cells from his umbilical cord and injected them into Molly. Umbilical cord cells can repopulate the bone marrow with healthy cells which then give rise to the immune system cells essential to maintaining health. In the UK, PGD can only be used for treating serious genetic disorders. This brings up many ethical issues.