Choroideremia

Choroideremia happens when there is a change in the CHM gene on the X chromosome^{. 3}

This gene is responsible for producing a protein (REP1) that helps maintain healthy retinal cells. When the gene does not work properly, the cells in the retina gradually stop functioning and die.

Because the condition is inherited in an X-linked pattern, this also means that:

Males are more likely to be affected

Females are usually carriers but may have mild symptoms

This gradual damage to the retina is what causes vision to worsen over time in people with choroideremia.

Choroideremia is often diagnosed through a combination of:

Eye examinations

Looking at family medical history

Genetic testing

When you have an eye examination, a practitioner may use imaging techniques such as optical coherence tomography (OCT) or fundus photography to look at the structure of the retina and spot any patterns of damage. Visual field tests may also be used to assess any loss of peripheral vision.

Carrying out genetic testing also allows them to confirm the diagnosis by identifying changes in the CHM gene 4. This can also help to determine whether any other family members may carry the condition.

The appearance of the retina, along with the possibility of inheritance within a family, are the main identifiers that will allow specialists separate choroideremia from other inherited retinal conditions, such as retinitis pigmentosa. Catching it early is important for monitoring the condition and exploring eligibility for clinical trials.

Common early and later symptoms include:

Night blindness and difficulty seeing in low light
Loss of peripheral (side) vision
Increased “tunnel vision”
Finding it tricky to navigate dim environments
Loss of central vision

Most people tend to find that night blindness is the first symptom, usually appearing in early years or throughout adolescence.

As the condition progresses, the visual field can become narrower until only central vision remains, which could potentially decline in later life.

Choroideremia is an area of active research, particularly in genetic therapies:

Clinical trials are exploring whether introducing a healthy version of the CHM gene into retinal cells can slow or prevent further degeneration.

While these treatments are still being developed, they offer hope for future therapies that could preserve vision in people with inherited retinal conditions.

Potential treatments:

At Sight Research UK, we are working tirelessly to find solutions to treat sight loss, including Choroideremia . Your eye specialist can let you know if there are any clinical trials you could participate in or you can find an active clinical trial here. Here are just a few of our projects that we’ve been working on with researchers all over the UK: