05 May 2004
ByAppeared in BioNews 257
US doctors report that they have helped five couples to have IVF babies which are able to provide tissue-matched cord blood for ill siblings. Four of the so-called 'saviour siblings' were conceived to help children with leukaemia, while another was born to help Charlie Whitaker, a British boy affected by Diamond-Blackfan anaemia. Scientists and clinicians at the Reproductive Genetics Institute in Chicago have now published details of the procedure, which involves genetic testing of embryos to establish their tissue type. The authors, who published their findings in the Journal of the American Medical Association, claim the technique has 'wide implications in medical practice'.
The Chicago doctors helped the Nash family conceive the world's first saviour sibling, a baby boy born in October 2000. Adam Nash provided umbilical cord blood stem cells used to treat his sister Molly, who was affected by a rare genetic condition called Fanconi's anaemia. The procedure involved testing IVF embryos to identify those which were both free from the disease, and also a tissue match for Molly. The five latest cases have sparked debate in the US, since all the embryos were tested solely for tissue type, and not for any genetic condition. Gilbert Meilander, a member of the President's Council on Bioethics, called the technique 'morally troubling'.
The doctors treated nine couples, who had existing children affected by acute lymphoid leukaemia, acute myeloid leukaemia, or Diamond Blackfan anaemia. After testing a total of 199 embryos, they identified 45 tissue-matched embryos for implantation. The team used 28 of these in 12 IVF cycles, which resulted in five singleton pregnancies. 'Screening embryos is still highly controversial and even not allowed in some countries, but it appears to be a reasonable option for couples', said the Institute's director Yury Verlinsky. The Whitaker family travelled to Chicago for treatment, after being refused permission to have the procedure carried out in the UK.
A new poll suggests that the majority of Americans support the use of PGD (preimplantation genetic diagnosis) for establishing tissue type only. A survey of 4005 people by the Genetics and Public Policy Center revealed that 61 per cent approve of using PGD to help an ailing sibling, while 33 per cent disapprove. By contrast, 57 per cent of respondents disapprove of using PGD to select embryos on the basis of sex. However, 80 per cent expressed concern that if not regulated, genetic technologies such as PGD could 'get out of control'. 'There is strong support for using these technologies when there is a health benefit, even when that benefit is for another person, but this support coexists with deep-seated worries about where all these new technologies may be taking us', said Center director Kathy Hudson.