current status of preimplantation genetic diagnosis

since its first clinical application in early 90s, preimplantation genetic diagnosis (pgd) has became a powerful diagnostic procedure in clinical practice for avoiding the birth of an affected child as well as increasing the assisted reproductive technologies (art) outcome . the technique involves the screening of preimplantation embryos for chromosomal abnormalities in certain indications such as advanced maternal age, repeated abortions and translocations, or for single gene defects, the majority of which are cystic fibrosis and thalassaemias. in this context, it becomes an alternative option for traditional prenatal diagnosis. so far, more than 1000 unaffected babies have been born after pgd, indicating that the procedure is safe and effective in prevention of genetic defects as well as increasing the art outcome. besides its diagnostic value and expanding indications such as cancer predisposition, dynamic mutations and late onset disorders, a new feature, namely preimplantation human leuckocyte antigen (hla) typing also demonstrates its novel therapeutic role in contemporary medicine. this article summarizes the recent status of pgd and discusses the current limitations and future perspectives associated with pgd techniques . key words:   pgd, art,fish