Exploring the Genetics of Retinitis Pigmentosa

Retinitis pigmentosa (RP) is a rare eye condition that causes vision loss over time. It affects the part of the eye that senses light (retina). At the early stages of RP, you may have trouble seeing at night and then lose side (peripheral) vision. Central vision, which is essential for fine-detail tasks, like reading, driving, and recognizing faces, eventually gets worse. RP affects about 1 in every 4,000 people around the world.

Causes of RP

RP is almost always caused by changes (mutations) in genes passed down through families. There are 3 main ways RP can be inherited:

• Autosomal recessive (about 50% to 60% of cases): A person gets 1 faulty gene from each parent. The parents don’t usually have symptoms.
• Autosomal dominant (about 30% to 40%): A person only needs 1 faulty gene to get RP. If a parent has it, each child has a 50% chance of getting it.
• X-linked (about 5% to 15%): This type mostly affects boys. Girls can carry the gene and may have mild symptoms.

RP Is Genetically Complex

RP is caused by many different gene mutations. Scientists have found over 56 genes and 3,100 mutations linked to non-syndromic RP (RP that only affects the eyes). Even the same gene mutation can cause different symptoms in different people, and similar symptoms might come from different genes. This makes it challenging for doctors to diagnose RP and predict how it may affect someone.

Why Genetic Testing and Counseling Matter

While eye exams and special retina imaging tests help diagnose RP, genetic testing can help figure out the type of RP you or a family member has. This can help your doctor understand how your RP symptoms may change over time and guide your future care.

Genetic counseling can also help you understand how RP runs in families and what the chances are of passing it on to your children. A counselor can explain test results to you and talk about next steps.

Management of RP

There’s no cure for most types of RP, but some treatments may help protect vision for longer and manage its symptoms, such as:

• Using vision aids to magnify and improve visual clarity
• Wearing UV-blocking sunglasses to help slow damage from light exposure
• Treating related issues, such as cystoid macular edema (CME), a common complication of RP that causes fluid build-up in the retina, leading to blurry vision and glare; if left untreated, CME can worsen retinal damage of RP
• Asking about gene therapy. An FDA-approved treatment is available for a specific type of RP (RPE65 mutations). More gene therapies are being studied. Depending on the results of genetic testing, you may eligible to take part in a clinical trial investigating new gene therapies for RP
• Taking supplements, such as vitamin A, fish oil, and lutein, that may help slow vision loss; however, vitamin A can be risky in high doses for some people, so always talk to your doctor before starting any supplements

If you or someone in your family is experiencing vision changes, especially trouble seeing at night or losing side vision, talk to your doctor. Regular eye exams and early testing, including genetic testing, can help you and your doctor identify RP and create a plan to manage it.