What is infertility?
Genetics and Infertility
Genetic Testing for Infertility
There are now available advanced techniques of genetic analysis which make it possible to screen eggs and embryos for specific abnormalities. The basic technique - preimplantation genetic diagnosis, or PGD - was successfully introduced more than 20 years ago and was designed to detect genetic alterations in the embryos of couples known to be at risk of passing on inherited disease to their children. These were usually fertile couples, whose only need of IVF was to provide a number of embryos for analysis from which a few might be "diagnosed" as unaffected.
More recently, PGD technology has been applied to the IVF embryos of infertile couples undergoing IVF treatment in the hope that the identification of chromosomally normal embryos for transfer will improve IVF success rates. There is growing evidence that miscarriage and failed implantation in IVF are largely explained by chromosome imbalance in the embryo, which is why the technique of embryo or egg screening by PGD may be especially worthwhile in women with a history of miscarriage, failed IVF cycles and in those of an older maternal age. We know that the risk of having a baby with a chromosome abnormality increases with age; Downs syndrome, for example, is caused by an extra copy of chromosome 21. Any couple who have had a pregnancy diagnosed with a chromosome abnormality would be advised to consider PGD.
The latest techniques of embryo screening by PGD use a method known as array CGH. All chromosomes can be assessed and only embryos identified at low risk of chromosome abnormalities are selected for embryo transfer.