Can genetic diseases such as cystic fibrosis, hemophilia and muscular dystrophy be treated with gene therapy?Genetic diseases and gene therapy:Genetic diseases are pathological diseases caused by absence or alteration of one or more genes in the cells of an organism. Most genetic diseases are caused by inheriting an altered or missing gene from one or both parents. Because the altered gene is found in every cell of the body, including stem cells, it is virtually impossible to physically alter the gene. The only effective way that has been found is gene therapy. Gene therapy is the insertion of normal or genetically modified genes into cells to replace defective genes. The gene is usually inserted into an organism's cells using a genetically modified virus that injects the desired gene into the organism's cells, rather than a harmful disease.Fig. 1: A diagram showing two types of gene therapy. Source: http://www.stemcells.nih.gov Cystic Fibrosis: Cystic fibrosis (CF) is a genetically inherited disease that affects the lungs, pancreas, liver, and intestines. Cystic fibrosis is caused by alterations in the cystic fibrosis conductance regulator (CFTR) gene. Because the alteration is recessive, to have cystic fibrosis you must receive an altered CFTR gene from both parents. The alteration causes abnormal transport of sodium and chloride across a membrane. This causes thick mucus to build up on the membrane which can block airflow into the lungs. Thick mucus in the lungs also causes frequent lung infections.Fig. 2: A diagram showing the inheritance of the CFTR gene.Source: http://www.nhlbi.nih.gov/Although cystic fibrosis poses many threats, the greatest threat is to the lungs, as thick mucus makes the lungs vulnerable. .... half of the article ......the University of Missouri tested the use of adeno-associated virus as a gene carrier on 22 dogs. The result of the treatment was a dramatic decrease in muscle inflation and fibrosis in all 22 dogs. All dogs also showed improvement in strength. In some cases, dogs who had difficulty walking were able to run after treatment. The images below show the muscle of one of the dogs before and after the treatment. The rounded cells are dead cells and the blue parts are inflammation.Fig. 6: Muscle cells from a dog affected by DMDSource: www.nbsubscribe.missouri.eduFig. 7: Muscle cells from the same dog after gene therapySource: www.nbsubscribe.missouri.eduConclusion: The results of the dog tests look promising and may provide a cure for MD in the future. Further testing and clinical trials in humans need to be done before the evidence can be conclusive.