PHILADELPHIA (WPVI) -- The Children's Hospital of Philadelphia says it's used gene therapy for the first time in the U.S. to treat genetic hearing loss.
An 11-year-old boy received the experimental treatment back in October.
The boy, who was born deaf in both ears, now only has mild to moderate hearing loss in the ear that was treated.
Five hospitals in total are testing the treatment.
The study may open the door for treating the other 150 genes that cause deafness.