Call to screen all IVF embryos for abnormalities
Dr. Kirsty Horsey
Progress Educational Trust29 May 2005
Testing embryos for chromosomal abnormalities before they are returned to the womb can dramatically improve the 'take home baby rate' for some patients, according to a US fertility doctor. Speaking at the Sixth International Symposium on Preimplantation Genetics, held in London last week, Yury Verlinsky of the Reproductive Genetics Institute in Chicago said that such testing should become a routine part of IVF treatment.
Preimplantation genetic screening (PGS) involves checking embryos for certain aneuploidies - chromosome errors that could affect normal development. It is different from preimplantation genetic diagnosis (PGD), in which an embryo is tested for a single genetic disorder. The Human Fertilisation and Embryology Authority (HFEA) first licensed PGS in 2002, and the first reported UK birth following the use of this technique was in 2003.
Verlinsky and his colleagues found that screening embryos dramatically increased the success rate for women with a history of recurring miscarriages, or for women over 35 undergoing IVF. The team claims that for these patients, the take-home-baby-rate increased from 11.5 per cent to 81.4 per cent when they used the technique. The scientists tested the polar body, a cell left over from the developing egg, so only studied the chromosomes inherited from the mother.
At a press conference held at the start of the meeting, Verlinsky said that embryo screening should be carried out for all patients undergoing IVF. 'About 40-70 per cent of all embryos are somewhat abnormal and this is human nature. So by selecting to transfer only a normal embryo, we fulfil our dreams to have a healthy child', he said. UK fertility pioneer Robert Edwards agreed with Verlinsky, saying 'the time has come that when we transfer an embryo, we should transfer a normal embryo'.
James Watson, famous for discovering the DNA double helix, also spoke at the meeting, on his current work to identify genes involved in autism. Watson, Edwards and Verlinsky all backed the use of PGD to select a baby's sex, for 'family balancing' reasons - couples who already have children of one sex, and wish to have a child of the opposite sex. Watson described the current HFEA ban on sex selection as 'pompous' and absurd'.
Edwards also called for PGD to be available on the NHS, which he said would be cost-effective compared to the expense of lifetime care for a seriously ill child. A spokeperson for the Department of Health told the BBC News website that the safety, clinical effectiveness and relative health benefits of PGD would need to be assessed before any decision about widespread provision could be made.
Reproduced with permission from BioNews, an email and online sources of news, information and comment on assisted reproduction and genetics.