'Saviour sibling' is a perfect tissue match
Dr Kirsty Horsey
Progress Educational Trust
24 July 2003
This week sees more good news for Michelle and Jayson Whitaker, the British couple who were refused permission by the UK's Human Fertilisation and Embryology Authority (HFEA) to use embryo screening (PGD) to provide a bone marrow donor for their sick son. The Whitakers, who travelled to Chicago for the IVF treatment that would potentially save their existing son, Charlie, have received confirmation that their new son, James, is definitely a perfect tissue match for his brother. Despite the use of the embryo screening procedure, there remained a two per cent chance that this would not be the case, said the couple's UK doctor, Dr Mohammed Taranissi.
Charlie Whitaker suffers from Diamond-Blackfan anaemia, a rare disorder of the blood which means he has to undergo a blood transfusion every three weeks. His only chance of living beyond about 30 years is a bone marrow transplant from a compatible donor. The Whitakers have had a daughter since Charlie, but she is unfortunately not a tissue match. Rather than leaving it to chance again, the Whitakers sought PGD to ensure that their next child would be able to help Charlie. But the HFEA said that it could not authorise the treatment because the Whitakers were seeking PGD for tissue typing alone, and not to ensure the embryo was itself free from a serious condition.
In October 2002, the couple travelled to the Reproductive Genetics Unit in Chicago for IVF treatment with PGD. They produced nine healthy embryos, from each of which a single cell was tested to see if the embryo would be a tissue match for Charlie. Three of the embryos were a close match and the best two were implanted into Michelle. One of the embryos successfully implanted and, as a result, James Whitaker was born on 16 June 2003 at a hospital in Sheffield, UK. A sample of the baby's umbilical cord blood was taken and sent to the Chicago clinic for testing to confirm the tissue match with Charlie - the results have just come back positive. The remaining cord blood is stored at a stem cell unit in Oxford until it is needed for transplantation. The family have been advised to wait six months before considering the stem cell transplant in case signs of the blood disorder appear in James. The causes of Diamond-Blackfan anaemia are unknown, but the illness can sometimes run in families.
On hearing the news, Jayson Whitaker said 'We are really ecstatic. It's really good news and we see it as one more positive milestone on the journey towards getting Charlie better'. However, despite the tissue match, the couple have not yet firmly made up their mind to go ahead with the stem cell transplant because the procedure carries a five per cent risk of death for Charlie.
© Copyright Progress Educational Trust
Reproduced with permission from BioNews, an email and online sources of news, information and comment on assisted reproduction and genetics.
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