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What is this “Gene Therapy”? How does it work? What is its significance/benefits in society? How is technology used in this? What ethical issues might this involve? What are the potential problems of this? What is Gene Therapy? -a simple definition by Karen Chen Gene therapy is a relatively new technique used to treat genetic disorders and diseases. The method is mainly used to correct defective genes that are responsible for the development of the disease. The most common practice of gene therapy is to replace a mutant allele* with a functional one. *for definition, visit http://dictionary.reference.com/browse/allele How Gene Therapy Works In the majority of studies on gene therapy, an ‘abnormal’ (disease-causing) gene is replaced by a ‘normal’ one by having the therapeutic gene inserted into the target cells of a patient. This is done by using carrier molecules called vectors to deliver the ‘normal’ gene to where it’s needed. Believe it or not, the most commonly used vector is a virus. Not any old virus though, these viruses have been genetically altered to carry normal human DNA. Nowadays, viruses have evolved a way of taking their own genes and delivering them to human cells to cause illness. Scientists have been able to use this to their advantage however by using this ability of theirs and manipulating the virus genome to remove the disease causing genes and insert remedial ones. If, for example, we wanted to replace abnormal cells in the liver, we would infect the patient’s liver cells with the viral vector. The vector will then dump its genetic material containing the normal human gene into the target cell. With the new therapeutic gene, the cell will generate functional protein which restores the cell to a normal, healthy state. Now, would everyone please have a look at this website: http://www.fda.gov/fdac/features/2000/gene.html TorontoIt seems that everyday now a new biotechnology project comes in and you wish you had paid more attention in b i o l o g y c l a s s . At a press conference concerning recent developments in gene therapy research, a brave man dared to ask, “How is gene therapy significant to us?” Dr. Peter Evans of the Gene Therapy Research Organization (GTRO) cleared his voice before answering, “Gene therapy is really an exciting topic. It can be used to do so much. Most commonly, we use it to treat genetic disorders like severe immunodeficiencies and so on. We’re expanding its uses all the time though, we have guinea pigs that were deaf with it, and we recently had scientists prove that gene therapy can be used to effectivel y treat cancer.” “It can be used to do so much,” that quote sums it up pretty well. Upon further research, I saw the names of disorders and diseases treatable by gene therapy stacking up. Genetic disorders like X-SCID (severe combined immunodeficiency) or the "bubble boy" disease, sickle cell, myeloid blood diseases, even blindness were among a list of many others with results in varying success. Even Alzheimer's and weight loss made the list. For the future, gene therapy is looked at as a possible treatment for Parkinson’s and is already on its road to becoming an effective cure to some cancers. Ways of using gene therapy as a prevention technique against cancer and diabetes is also being looked into. If I were to bet my bottom dollar on how significant gene therapy is, I would; it’s just that significant. Hmmm. IWhere Actually, am going the next tocould check my email, clue be? I deserve a break. Now ITo: Adeno-associated dug is when [email protected] some vectors information viruses come into can on your play. insertbehalf The theirmost genetic as Agent common 000 008 Anyway, the outline consists of the following. delivery told memethod material to athelp a specific isout. to use There site a on viral is a chromosome vector range which of delivery 19. is aWhile virus that From: 307 [email protected] has techniques Herpes simplex ‘deactivated’ and viruses several infect (its different neurons. genes types of vectors removed) that socan 1. been The faulty gene that is own causing theare disease must be that carry itidentified. isout harmless. the delivery Sinceof viruses the can slipgenes. into cell First and of take all Subject: Technology GThealthy As great asand viruses are as vectors, there are over though, their DNA, the affected scientistscells realised needthey to be could taken use from thisthe ability many other methods of delivering the genes. Out of 2. You must locate the exact position of the affected Gene Therapy itself is considered a technology topatient enter awhere specific thecell correct and deliver genetic the information healthy gene. is then these, the simplest one would be to introduce the cells but Agent 000 told me to give either ‘spliced’ or injected intoyou the some cells. info about the remedial There genes are directly several into different target cells typesbut of that viruses used specifics on the different kinds of vectors used forwould the process 3. A healthy version of the gene must be available to asrequire vectors large in Splicing gene amounts therapy. used of for DNA Retroviruses gene and therapy it can like only is Human when be used the of gene therapy. I alsoone found an outline of the steps in on the replace the faulty immunodeficiency incorrect certain tissues. gene is Another cut virus out (HIV) non-viral from can the create method DNA sequence double-stranded would be and to process of gene therapy that I thought might be useful to DNA then get therapeutic modified of their tosort genes contain RNA genomes. into the the correct targets The genetic copies by chemically of information. genomes 4. copies Using some of vector, the healthy gene must be you. from After linking this it the is class modified, DNA of virus to a it can molecule is then be inserted integrated that will into bind into a vector the to special of some delivered to the cell. I was searching through my of oldviruses whenare I chromosomes sort for cell receptors. delivery ofWhen host into the cells. these patient. Other are attached types tonotes the used Now, technology comes into play considerably came across this outline of DNA the basic stepsisin gene therapy Adenoviruses receptors, the like therapeutic the common-cold, structure Adeno-associated engulfed by during this process. And the information about them and thought that I’d save you some trouble and send viruses the cell and membrane Herpes simplex and passed viruses;into each thewith inside its own of the it to was extremely difficult to cometends across. However, you. advantages. target cell. This method however, to be far less effective. Somatic gene therapy is performed on adults who are known to have the disease while germline therapy is done is egg and sperm cells to prevent a Do they need to be cured or prevented? trait from being passed down from generation to generation. Some say: Yes, life is simply much easier without I personally think that germline therapy is perfectly acceptable. Idealistically Some say:with Everyone and anyone should have access to these therapies. We are having to deal a disability and no one should speaking, if we prevented traits from being passed down, we could to equal rights and should be able to have the therapy we need haveall to entitled go through life like that. eventually get rid of a disease altogether. It also feels more safe knowing performed no matter who we are and how much money we have. The that say: you won’t inherit adisability disorder doesn’t from your parents or that you won’t pass one Others No, having government shouldapay for our fees, ormake at least subsidize them. If a treatment is on to your children. On the other hand, it is also unfair to determine you any less human and you shouldn’t available, anyone should be able tobegoregarded have it done, no matter their financial something forshould others we without them differently. Why try soletting hard to curehave the chance to make a situation. decisionmany for themselves. This would make somatic gene therapy more ‘fair’ disabilities people are living with today? It is since it demeaning is your personal but when we are born, we also have no practically their decision existence. hand in deciding what genes we want. Others say: As much as we’d like to idealize and say that everyone should be able to have gene therapy performed, our society simply doesn’t work that way. It is extremely costly to have to procedure done and that kind of money is difficult to come by. There is almost no way that a patient could have it done for free without some serious changes like huge increases in funds or higher taxes in countries. A potential patient would have to be very financially secure for this treatment which unfortunately, at least for now, cannot be accessed by all. Short-lived results of gene therapy For gene therapy to be a permanent cure, many requirements must be met. First of all, the therapeutic DNA introduced into target cells must remain functional and secondly, the cells containing them must be stable and live for a long period. Long-term benefits can be prevented from success with all the problems integrating therapeutic into the genome and the fact that some cells’ rapid dividing Viral VectorDNA Problems nature keeps gene therapy from ‘sticking’. As a result, patients often have to Viruses usually theofmost common choice for vectors and viruses, undergo are several rounds the treatment. although genetically altered, come with some risks. Such risks would Multigene Disorders include: toxicity, immune and inflammatory responses, and gene control and targeting issues for the patient. there always the high fear that Many of the most commonly occurringFinally, diseases like is heart disease, blood once the Alzheimer's virus has entered patient,and it may recover its ability pressure, disease,the arthritis, diabetes, are caused byto thespread effects of disease. variations in many different genes. The best candidates to receive gene therapy are disorders that arise from mutations in a single gene so treating diseases like those aforementioned would be difficult. Immune Response Our immune system is meant to attack foreign objects when they invade our bodies so there is always a risk of stimulating the immune system in a manner that would reduce the effectiveness of the treatment. And since gene therapy is often used on a patient several times, it becomes more difficult to perform since the immune system is especially good at responding to invaders it is familiar with.