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Use and misuse of preimplantation genetic testing

BMJ 2007; 335 doi: (Published 11 October 2007) Cite this as: BMJ 2007;335:752
  1. Peter Braude, director,
  2. Frances Flinter, clinical director of children's services and genetics
  1. Centre for Preimplantation Genetic Diagnosis, Guy's and St Thomas' Foundation Trust, Guy's Hospital, London SE1 9RT
  1. Correspondence to: P Braude peter.braude{at}

    Detection of genetic diseases before implantation for couples at risk helps ensure healthy children, but testing for aneuploidy does not improve the chances of live birth in normal infertile women, say Peter Braude and Frances Flinter

    A randomised trial in the New England Journal of Medicine has rekindled the acrimonious debate about the efficacy and appropriateness of testing for chromosomal imbalance (aneuploidy) before implantation in older infertile women having in vitro fertilisation.1 These women have such a poor prognosis of having a child by in vitro fertilisation that many will latch on to any promise that might improve their odds. This is the second randomised trial that shows no benefit from preimplantation genetic screening, yet advocates are unwilling to accept the findings. We examine the place of genetic testing of embryos in modern medical practice and possible future uses.

    Preimplantation diagnosis

    Preimplantation genetic diagnosis (PGD) was developed as an alternative to prenatal diagnosis and possible termination of an affected pregnancy for couples at risk of passing on a serious genetic disease to their children.2 3 It has an important place in preventing transmission of inherited conditions where the child has a high risk of dying early (such as spinal muscular atrophy),4 of severe mental or physical disability (such as unbalanced chromosome translocations),5 or of diseases such as Duchenne muscular dystrophy or cystic fibrosis that develop in childhood and shorten lifespan. In some cases the effect of the disease is so severe that it results in repeated early miscarriage (chromosome imbalance) or later fetal, neonatal, or infant death. Each of these conditions can be detected before implantation, provided the mutation within the relevant gene is known, the chromosome carrying the gene can be tracked through the family tree, or the specific chromosomal rearrangement has been identified.3

    The technique …

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