What is retinisis pigmentosa?
Retinisis pigmentosa is a hereditary dystrophy of the retina (link), classed as a “rare” disease that affects 2 or 3 out of 10,000 people and is the main cause of genetic blindness in the adult population.
This disease progressively damages the retina (the innermost layer of the eye), leading to the loss or “programmed cell death” of its photoreceptor cells. These are responsible for turning the light stimuli entering the eye into nerve or electric signals that are sent to the brain. Retinisis pigmentosa typically affects the photoreceptors known as rods (responsible for peripheral vision) and respects the cones (responsible for central vision). However, general atrophy of the retina might occur during final stages.
Despite being born with the disease, retinisis pigmentosa does not often become apparent until adolescence or young adulthood, and the age at which it appears varies. The first signs are normally poor night vision (failure to adapt to the dark) and the progressive reduction of the visual field. As the disease progresses, flashes are often seen and, in more advanced stages, a decrease in visual acuity and altered perception of colours.
Retinitis pigmentosa is a hereditary disease and there are different mutations in several possible genes that trigger the mechanisms causing it, to different degrees of severity. There are three types of inheritance that determine the evolution of the disease and the visual prognosis, although there are some sporadic cases that have no family history.
- Dominant inheritance: all carriers of the mutation have the disease, but this is the case with the best prognosis.
- Recessive inheritance: the carriers of a single mutation are healthy and those with two mutations in the same gene develop the disease. The prognosis is intermediate.
- X-linked inheritance: only men suffer from the disease (women are carriers). This case has the worst prognosis.
To date, over 2,000 mutations and 200 genes associated to retinisis pigmentosa are known, but there are still several yet to be identified. Our group offers a service of genetic diagnosis from the IMO Miranza Group laboratory and, through the R&D+i area, we develop research projects headed by the IMO Foundation to progress in our knowledge of the molecular basis of this disease.
Retinisis pigmentosa is currently an incurable disease, as the damaged photoreceptor cells cannot be recovered. However, there are several lines of research to develop new treatments and, in factor, the first gene therapy known as Luxturna has recently been marketed, which is personalised for patients with retinisis pigmentosa with mutations in the RPE65 gene. This drug introduces a health copy of the damage gene so that the retinal cells can recover their normal function, thus slowing down the progression of the disease and, therefore, the loss of vision.
At Miranza we are involved in research to open the door to future gene therapies, such as cell therapies and artificial or bionic vision chips that will restore visual perception in cases in which the disease is already extremely advanced.
Given that retinal dystrophies such as retinisis pigmentosa cannot be prevented because they are genetic, early diagnosis is essential in order to appropriately monitor their evolution and for the early detection of treatable complications (such as cataracts, macular oedema or epiretinal membranes) Vision Department.