Preimplantation genetic diagnosis of haemophilia.

Preimplantation genetic diagnosis (PGD) aims to increase the number of options available to couples who could have a child affected with haemophilia and reduce the anxiety these couples often associate with reproduction. The female partner must undergo an in vitro fertilization cycle, and the eggs or embryos are then biopsied. Embryos which are unaffected by haemophilia can then be transferred to the uterus. The clear advantage of this technique is that the woman knows from the very beginning that the pregnancy is unaffected by haemophilia, and she can avoid conventional invasive prenatal diagnosis and the difficult decision on whether or not to terminate an affected pregnancy. Several strategies for this single cell genetic diagnosis have been described. These include embryonic sexing using polymerase chain reaction, embryonic sexing using fluorescent in situ hybridization, specific diagnosis using restriction enzymes, sequencing and haplotype analysis. Over the years, PGD has attracted much ethical commentary, both supportive and critical, regarding the fundamental principles of embryo selection and destruction. New scientific advances and their potential applications are considered.