Choroideremia (CHM) is a rare inherited disorder that causes progressive vision loss, ultimately leading to complete blindness. It is also known as choroidal sclerosis, progressive choroidal atrophy or progressive tapetochoroidal dystrophy. Choroideremia is designated as a rare disease as it affects an estimated 1 in 50,000 to 1 in 100,000 people.
The disease affects the retina, which is the area at the back of the eye that gives us vision. The disease is caused by a genetic defect of the X chromosome. Males suffer the full effects of the condition while females experience less severe symptoms and can be carriers.
Choroideremia is sometimes misdiagnosed as other retinal conditions such as retinitis pigmentosa (RP) due to the similarity of symptoms. The family inheritance pattern of mainly males being affected and the characteristic pattern of the back of the eye can help with diagnosis. However, choroideremia is a prime example of where genetic diagnosis can be crucial to receiving the correct diagnosis. You can find more information on genetic testing for IRDs in our Genetic Testing Toolkit http://www.retina-international.org/genetics/