Choroideremia is a rare blinding genetic eye disease affecting approximately one in 50,000 people. Usually, the first signs are seen in young boys – sometimes as early as age five. In the disease, blood vessel networks, pigment and light-sensing cells in the eye’s retina slowly stop working and eventually die.
Initially, night-blindness and ‘blind spots’ (resulting from vision loss in the mid-periphery) typically occur, but as time passes, central vision is also affected, leaving patients with tunnel vision. With no cure currently available, the disease slowly progresses until vision is lost, resulting in blindness.
Choroideremia is caused by a genetic defect of the X chromosome and so it usually affects males. In approximately 30% of people with the disease, the defect is described as a nonsense mutation, which causes an abnormal ‘stop’ sign in the genetic code.