Four young adults who suffer from a genetic disorder that causes vision loss have volunteered for a trial study that involves injecting DNA into the eye to hopefully halt vision loss. The injections deliver fresh new DNA into the eyes. Gene therapy is based upon the premise that if a disease is caused by a single faulty gene, then swapping the faulty gene out with a healthy version should correct the problem or problems. However, gene therapy is not always successful because it can be difficult getting the fresh DNA¬† into cells and there is no guarantee that the patient's cells will accept the new gene and use it. Doctors reported earlier in September that they had successfully treated children in the United States for the "bubble boy" disease with gene therapy. And two chronic lymphocytic leukemia patients went into remission after receiving another type of gene therapy last year. Researchers are hopeful that the DNA injections into the eyes of the patients will be successful and stop their vision loss and pave the road for successful treatment in future patients.