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Gene therapy is the therapeutic delivery of nucleic acid polymers into a patient's cells as a drug to treat disease. Until September 1990, it had never been successfully done, and it is still an experimental and emerging medical technology that has seen new promise in the 2010s after extensive challenges and setbacks in the first two decades of its existence. Between September 1990 and January 2014 some 2,000 clinical trials had been conducted or approved.〔(Gene Therapy Clinical Trials Worldwide Database ). ''The Journal of Gene Medicine''. Wiley (January 2014)〕〔http://archive.hhs.gov/news/press/1995pres/951019a.html〕 It should be noted that not all medical procedures that introduce alterations to a patient's genetic makeup can be considered gene therapy. Bone marrow transplantation, and organ transplants in general have been found to introduce foreign DNA into patients.〔http://www.nytimes.com/2013/09/17/science/dna-double-take.html?pagewanted=all&_r=1〕 Gene therapy is defined by the precision of the procedure and the intention of direct therapeutic effects. ==Background== Gene therapy was conceptualized in 1972, by authors who urged caution before commencing human gene therapy studies. The first attempt, albeit an unsuccessful one, at gene therapy (as well as the first case of medical transfer of foreign genes into humans not counting organ transplantation) was performed by Martin Cline on 10 July 1980.〔https://books.google.com/books?id=FxGjBqEL-3kC&pg=PA45&lpg=PA45&dq=%22martin+cline%22+%22gene+therapy%22&source=bl&ots=Goj5oCAVBp&sig=KbB9EHE4ucGkS1C2AUVltD-A4-U&hl=en&sa=X&ved=0CD8Q6AEwBWoVChMIyczEkPrRyAIVTcNjCh1NBg3U#v=onepage&q=%22martin%20cline%22%20%22gene%20therapy%22&f=false〕〔http://www.ncbi.nlm.nih.gov/pubmed/7123214〕 Cline claimed that one of the genes in his patients was active six months later, though he never published this data or had it verified 〔https://books.google.com/books?id=FzuwRwb--X4C&pg=PA30&lpg=PA30&dq=%22gene+therapy%22+martin+cline&source=bl&ots=L0oOWFnD-i&sig=k751o-g-TgVgJnECRIRMcM4EcFU&hl=en&sa=X&ved=0CDQQ6AEwBjgKahUKEwja2rCXtvfIAhVP5GMKHVPWDWQ#v=onepage&q=%22gene%20therapy%22%20martin%20cline&f=false〕 and even if he is correct, it's unlikely it produced any significant beneficial effects treating beta-thalassemia.〔http://cshmonographs.org/index.php/monographs/article/viewFile/4773/3874〕 After extensive research on animals throughout the 1980s and a 1989 bacterial gene tagging trial on humans, the first gene therapy widely accepted as a success was demonstrated in a trial that started on September 14, 1990, when Ashi DeSilva was treated for ADA-SCID. The first somatic treatment that produced a permanent genetic change was performed in 1993.〔http://www.asgct.org/UserFiles/kohnslides.pdf〕 The first germ line gene therapy consisted of producing a genetically engineered embryo in October 1996. The baby was born on July 21, 1997 and was produced by taking a donor's egg with healthy mitochondria, removing its nuclear DNA and filling it with the nuclear DNA of the biological mother - a procedure known as cytoplasmic transfer.〔http://www.docguide.com/healthy-baby-born-after-worlds-first-successful-cytoplasmic-transfer〕 This procedure was referred to sensationally and somewhat inaccurately in the media as a "three parent baby", though mtDNA is not the primary human genome and has little effect on an organism's individual characteristics beyond powering their cells. Gene therapy is a way to fix a genetic problem at its source. The polymers are either expressed as proteins, interfere with protein expression, or possibly correct genetic mutations. The most common form uses DNA that encodes a functional, therapeutic gene to replace a mutated gene. The polymer molecule is packaged within a "vector", which carries the molecule inside cells. Early clinical failures led to dismissals of gene therapy. Clinical successes since 2006 regained researchers' attention, although as of 2014, it was still largely an experimental technique.〔 These include treatment of retinal disease Leber's congenital amaurosis,〔〔〔〔 X-linked SCID, ADA-SCID,〔 adrenoleukodystrophy, chronic lymphocytic leukemia (CLL),〔 acute lymphocytic leukemia (ALL),〔 multiple myeloma,〔Coghlan, Andy (11 December 2013) (Souped-up immune cells force leukaemia into remission ). New Scientist. Retrieved 15 April 2013〕 haemophilia〔 and Parkinson's disease. Between 2013 and April 2014, US companies invested over $600 million in the field.〔Herper, Matthew (26 March 2014) (Gene Therapy's Big Comeback ) ''Forbes''. Retrieved 28 April 2014〕 The first commercial gene therapy, Gendicine, was approved in China in 2003 for the treatment of certain cancers. In 2011 Neovasculgen was registered in Russia as the first-in-class gene-therapy drug for treatment of peripheral artery disease, including critical limb ischemia. In 2012 Glybera, a treatment for a rare inherited disorder, became the first treatment to be approved for clinical use in either Europe or the United States after its endorsement by the European Commission.〔〔 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「gene therapy」の詳細全文を読む スポンサード リンク
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