Preimplantation genetic diagnosis: new reproductive options for carriers of haemophilia.

Preimplantation genetic diagnosis for haemophilia offers couples at risk for transmitting the condition the opportunity to embark on a pregnancy knowing that the embryo is unaffected by the disease. The technique aims to increase the range of reproductive options available to these couples and remove the need for invasive prenatal diagnosis and the difficult decision on whether to terminate an affected pregnancy. This aims to reduce the anxiety associated with reproduction often seen in these couples. Patients undergo a cycle of in vitro fertilization followed by embryo biopsy. The single blastomeres are then analysed using fluorescent in situ hybridization to detect the sex of the embryo, and only female embryos are transferred to the uterus. Recently a PCR based approach has allowed specific mutation detection, and therefore the transfer of unaffected male and female embryos.