Ethics of using preimplantation genetic diagnosis to select a stem cell donor for an existing person

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Abstract
PGD for the benefit of a relative Children have been conceived to provide stem cells for their siblings. In the most publicised case, the Ayala case,8 Marissa Ayala was conceived in 1989 to provide stem cells for her sister Anissa. A later report noted, “Marissa is now a healthy four year old, and, by all accounts, as loved and cherished as her parents said she would be. The bone marrow transplant was a success and Anissa is now a married, leukemia-free bank clerk.”9 Assisted reproduction has been used to conceive children to provide stem cells for siblings.10 At the end of 1999, a couple in the United States underwent in vitro fertilisation and for the first time used PGD to screen their embryos for those whose tissue type matched that of their daughter, who had Fanconi's anaemia. Over four treatment cycles, five suitable embryos were implanted; one survived and at birth blood from the umbilical cord was harvested. This blood was used in a successful stem cell transplant for the daughter.11 In Britain the parents of a 2 year old boy with β thalassaemia applied in October 2001 to the Human Fertilisation and Embryo Authority for permission to select an embryo, using PGD, that can provide him with a matched stem cell transplant, again through umbilical cord blood taken at birth.12 These are the first publicly recorded cases of requests for PGD for the benefit of a relative; they are likely to herald further requests. In both these cases, the technique fulfils two functions. Firstly, it is used to select embryos that do not have the genetic mutation that affects the family (Fanconi's anaemia or thalassaemia). This is a standard indication for PGD. Secondly, it is used to select an HLA compatible stem cell donor from these embryos. Even more controversially, in both the United States and Australia there have been requests to use PGD to select a HLA compatible embryo to serve as a stem cell donor in the absence of any family history of genetic disease. Recently a British couple went to the United States to have in vitro fertilisation and PGD to select a stem cell donor for their child with relapsed leukaemia. The woman is currently pregnant.13