This page provides information about RP, its symptoms, causes and what treatment options are available. 

What is RP?

What is retinitis pigmentosa?

RP describes a group of inherited retinal diseases (IRDs) affecting the photoreceptor (light-sensing) cells which line the back of the eye, called the retina. People living with RP experience a gradual decline in their vision because the two photoreceptor cell types – rods and cones – degenerate and die.

Rods are responsible for vision in low light conditions, while also having an important role in peripheral (side) vision. Cones are most concentrated in the central region of the retina (macula) and have a prominent role in central vision (reading). Cones perceive bright light and are also necessary for color vision. In the early stages of RP, rods stop working which impairs vision in low light causing night blindness (nyctalopia). This is followed by blind spots that develop in our peripheral vision. Deterioration of cones follows, but many people living with RP maintain reasonable central vision well into adulthood.

Microscope image of rods and cones photoreceptors in a human retina

Microscope image of rods (green) and cones (red) photoreceptors in a human retina.
CC BY 2.0 / Robert Fariss, National Eye Institute, NIH

What are the symptoms?

What are the symptoms of RP?

Due to rods degenerating first, the initial signs and symptoms of RP are night blindness and difficulty transitioning between low and bright light. As peripheral vision progressively deteriorates, tunnel vision ensues and only central vision is maintained.

A list of all visual IRD symptoms can be found on our inherited retinal disease page.

RP has different genetic causes and may start at different ages. Some people are diagnosed with the condition in early childhood, while others might not be diagnosed until they are adults. How RP progresses and how vision is lost also varies between individuals. It is therefore very difficult to predict what a person’s vision will be like at specific times in the future. Both eyes are usually affected in a similar manner.

What causes RP?

What causes RP?

RP is one of the most complex genetic conditions, known to be caused by more than 50 genes and affects approximately 1 in 3,000 to 1 in 4,000 individuals worldwide. The nature of RP inheritance also contributes to this complexity, whereby RP-causing mutations can be passed from parents to children in an autosomal dominant, autosomal recessive or X-linked inheritance pattern.

 

Genetic testing

To know what mutation is causing RP, genetic testing is necessary. Genetic testing is the only way to receive an accurate diagnosis and will help find out if there are treatments or clinical trials available.

Genetic testing
Female scientist in the lab

Autosomal recessive retinitis pigmentosa

In autosomal recessive RP, both parents are carriers, unaffected by RP. Each parent has one mutated copy of the RP gene and one normal copy. Each of their children has a 25 percent risk of inheriting two mutated RP gene copies (one from each parent) which then cause RP.

Infographic describing autosomal recessive retinitis pigmentosa inheritance. The two parents at the top of the graph do not have RP, but each carry one copy of the RP gene and one normal copy. They are carriers of RP. Of their four children at the bottom of the graph one inherited two mutated genes and is affected by the condition (25% chance), two are unaffected carriers with one mutated and one normal gene (50% chance) and one has two normal genes (25% chance).

Autosomal dominant retinitis pigmentosa

In autosomal dominant RP (adRP) only one mutated copy of the RP gene is needed to develop the disease. A patient inherits one normal gene copy from the unaffected parent and one mutated RP gene copy from the affected parent. Each of their children has a 50 percent risk of inheriting the RP gene copy which then causes adRP.

Infographic describing autosomal dominant retinitis pigmentosa inheritance. One of two parents at the top of the graph has RP carrying one mutated gene and one normal gene. The other parent is unaffected with two normal copies of the gene. Of their four children at the bottom of the graph two have one mutated gene and have RP (50% chance), two are unaffected with two normal copies of the gene (50% chance).

X-linked retinitis pigmentosa

In X-linked RP, the RP gene is located on the X chromosome and therefore the disease is passed down differently in men and women. In men, having one X chromosome, only one copy of the RP gene is needed to develop the disease. In women, having two X chromosomes, usually two copies of the RP gene are needed to develop the disease. However, some women who carry only one copy of the RP gene still develop a mild form of RP.

Infographic describing X-linked retinitis pigmentosa inheritance. The father at the top of the graph is unaffected with one normal X chromosome. The mother is an unaffected carrier of RP with one mutated X chromosome. Of the four children at the bottom of the graph one son has RP with a single mutated X chromosome. A daughter is unaffected with two normal X chromosomes, a son is unaffected with a single normal X chromosome and another daughter is an unaffected carrier.
Is there a cure?

Is there a cure for RP?

As for most inherited retinal diseases, there is currently no approved treatment for retinitis pigmentosa. At ProQR, we are working hard to change that. We are developing two investigational RNA therapies for common mutations causing RP. 

Learn more about QR-421a and the ongoing Phase 1/2 Stellar clinical trial for USH2A mediated RP.

Learn more about QR-1123 and the ongoing Phase 1/2 Aurora clinical trial for RHO mediated RP.

 

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