Joint Israeli-US research has discovered that the absence of protein RFX in many elderly people causes hearing loss. The protein is responsible for maintaining tiny hairs (cilia) in the inner ear. When these hairs die off, the person becomes deaf. The team believe their discovery will help develop treatments to restore hearing in patients.

http://www.jpost.com/Business-and-Innovation/Health-and-Science/Breakthrough-find-may-lead-to-restoring-hearing-in-elderly-431761