Human Gene Therapy :: Science Genetics Papers

Human Gene Therapy Each of us carry about half a dozen defective genes. Most of us do not suffer any harmful effects from our defective genes because we carry two copies of nearly all genes, one derived from our mother and the other from our father. Because in the majority of cases, the potentially harmful gene is recessive, its normal counterpart will carry out all the tasks assigned to both. Only if we inherit from our parents two copies of the same recessive gene will a disease develop. Every year a considerable number of children are born with a genetic disease, a disease that occurs because each of their parents carries a defect in the same gene (Rigby 1995). The most common disease of this sort, with about couple thousand affected children born each year, is cystic fibrosis, which leads to a clogging of the lungs, and to problems with digestion and other functions. Although improvements in care and treatment mean that people with cystic fibrosis can now live for up to twenty-five years, there is no cure. A much rarer but nevertheless well known disease, is severe combined immunodeficiency (SCID). SCID children with this condition have a defect in both copies of a gene which is required for the proper functioning of the immune system. The children can be kept alive but they have to live in sterile plastic bubbles to isolate them from bacteria and viruses. These children would die of infections which would only keep the rest of us in bed for a couple of days. Again , while there are treatments, there is no cure. However, in simple terms the cure is obvious. If the children are ill because they have two bad copies of a gene, it follows that if we could give them a good copy of the gene they would then be like their parents and be healthy. This very obvious idea is called gene therapy. Concept of Gene Therapy Gene therapy is the insertion of a functioning gene into the cells of a patient to correct an inborn error of metabolism or to provide a new function in a cell. This is a very broad definition that includes the potential treatment of essentially all types of human disease through the genetic modification of cells of the human body to prevent or eliminate disease. There are two main types of gene therapy, germinal cell and somatic cell gene therapy (Culver 1996).