Pre-implantation genetic diagnosis: a preliminary report of 2 years of experience.

Background: Pre-implantation genetic diagnosis (PGD) is defined as making a diagnosis or screening embryos or gametes before implantation. It has the advantage of avoiding repeated spontaneous abortions or therapeutic termination of pregnancy resulting from abnormal embryos. Here, we present our preliminary report of 2 years of experience. Methods: From March 2001 through October 2002, couples seeking assistance for in vitro fertilization (IVF) were referred for PGD due to chromosomal problems or for aneuploidy screening (PGD-AS). One or two blastomeres were aspirated on day 3 and analyzed using the fluorescent in situ hybridization (FISH) technique. Probes to chromosomes X, Y, and 18 were used for aneuploidy screening and individual specific probes were chosen for chromosomal translocations. Unaffected embryos were transferred on day 5. Results: There were 25 cycles for aneuploid screening (group 1) and four cycles for chromosomal translocation (group 2). In group 1, 73 embryos were biopsied with a successful biopsy/fixation rate of 72.6% and a diagnosis rate of 96.2%. Fifteen unaffected embryos were transferred in 11 cycles, achieving two sets of twins and four singleton pregnancies (implantation rate: 53.3%). In group 2, 27 embryos were biopsied with a successful biopsy/fixation rate of 66.7% and a diagnosis rate of 88.9%. Seven non-affected embryos were transferred in three cycles, resulting in one set of twins (implantation rate: 33.3%). All antenatal amniocentesis confirmed the diagnosis. Post-natal physical examination showed no evidence of major abnormalities. Conclusions: PGD is an alternative method for having healthy children in selected couples with chromosomal abnormalities. In addition, PGD-AS may increase the implantation rate in infertile couples seeking IVF assistance. (Chang Gung Med J 2004;27:726-33)