Place of preimplantation diagnosis in genetic practice.

Preimplantation genetic diagnosis (PGD) is currently one of the practical options available for couples at-risk to avoid the birth of children with genetic and chromosomal disorders. Despite its novelty, PGD has already become an alternative to traditional prenatal diagnosis, allowing establishing only unaffected pregnancies avoiding the risk for pregnancy termination. Indications for PGD have currently expanded beyond those practices in prenatal diagnosis, such as late-onset diseases with genetic predisposition, and preimplantation HLA typing with the purpose of establishing potential donor progeny for stem cell treatment of siblings, which makes PGD also an important compliment to prenatal diagnosis. The fact that more than 1,000 apparently healthy unaffected children have been born after PGD suggests its accuracy, reliability, and safety. PGD is presently an excellent option for carriers of balanced translocations, and appears to be of special value for avoiding age-related aneuploidies in patients of advanced reproductive age. The accumulated experience of thousands of PGD cycles for poor prognosis in vitro fertilization (IVF) patients provides strong evidence of the improvement of clinical outcome, particularly obvious from the reproductive history of patients. This makes of practical relevance to inform couples at-risk about availability of PGD option, so they make their own choice in avoiding the birth of affected offspring and having healthy children of their own.