Experimental gene therapy improves vision in choroideremia patients

Choroideremia is a genetic eye disease which slowly causes blindness and is caused by defects in the CHM gene found on the X chromosome. The disease mostly affects men and there is no cure for the disease which affects 1 in every 50,000. An experimental gene therapy being tested by researchers at the University of Oxford replaces the defective gene with a healthy one in a single injection. Six patients were injected with a genetically engineered virus, which carried a corrective copy of the missing gene to the retina where it replaced the defective gene. These patients who underwent the therapy have showed improvements in their vision with one-third of them being able to read more lines on an eye chart. The improvements in vision have been maintained for two years with no side effects noted. Encouraged by these initial results, the researchers are testing higher doses on three patients to see if additional treatments will be more effective. The success of this therapy could have profound implications for patients with retinitis pigmentosa and age-related macular degeneration.