Choroideremia is a condition that causes gradual vision loss, primarily in males.
The first sign is usually difficulty seeing in the dark (night blindness), which starts in early childhood. As the condition progresses, the field of vision becomes narrower (tunnel vision), and the ability to see details decreases. These issues occur because cells in the back of the eye (retina) and nearby blood vessels (choroid) are gradually lost. The vision problems worsen over time, but the rate of progression varies from person to person. Eventually, everyone with this condition will become blind, typically in late adulthood.
Choroideremia is caused by pathogenic (disease-causing) variants in the ASS1 gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance to have a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background.
Other names for this condition are choroidal sclerosis, progressive tapetochoroidal dystrophy, and TCD.