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 …