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Pre-implantation genetic diagnosis (PGD or PIGD) refers to genetic profiling of embryos prior to implantation (as a form of embryo profiling), and sometimes even of oocytes prior to fertilization. PGD is considered in a similar fashion to prenatal diagnosis. When used to screen for a specific genetic disease, its main advantage is that it avoids selective pregnancy termination as the method makes it highly likely that the baby will be free of the disease under consideration. PGD thus is an adjunct to assisted reproductive technology, and requires in vitro fertilization (IVF) to obtain oocytes or embryos for evaluation. The term preimplantation genetic screening (PGS) is used to denote procedures that do not look for a specific disease but use PGD techniques to identify embryos at risk. The PGD allows studying the DNA of eggs or embryos to select those that carry certain damaging characteristics. It is useful when there are previous chromosomal or genetic disorders in the family and within the context of in vitro fertilization programs.〔(How does DGP work? Infographic ) Retrieved 28. June 2015〕 The procedures may also be called preimplantation genetic profiling to adapt to the fact that they are sometimes used on oocytes or embryos prior to implantation for other reasons than diagnosis or screening.〔(Page 205 ) in: 〕 Procedures performed on sex cells before fertilization may instead be referred to as methods of oocyte selection or sperm selection, although the methods and aims partly overlap with PGD. ==History== In 1967, Robert Edwards and Richard Gardner reported the successful identification of the sex of rabbit blastocysts. It was not until the 1980s that human IVF was fully developed, which coincided with the breakthrough of the highly sensitive polymerase chain reaction (PCR) technology. Handyside and collaborators' first successful tests happened in October 1989, with the first births in 1990 though the preliminary experiments had been published some years earlier. In these first cases, PCR was used for sex determination of patients carrying X-linked diseases. PGD became increasingly popular during the 1990s when it was used to determine a handful of severe genetic disorders, such as sickle-cell anemia, Tay Sachs disease, Duchenne’s muscular dystrophy, and Beta-thalassemia.〔Simoncelli,Tania."Pre-implantation Genetic Diagnosis: Ethical Guidelines for Responsible Regulation." CTA International Center for Technology Assessment. Retrieved on Nov. 19 2013 from http://www.andrewkimbrell.org/doc/pgd%20guidelines.pdf〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Preimplantation genetic diagnosis」の詳細全文を読む スポンサード リンク
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