Retinal dystrophies
Retinal Dystrophies
They affect less than 1 in every 2,000 people
More than 250 related genes are known
What are Retinal Dystrophies?
Retinal dystrophies are a heterogeneous group of hereditary diseases that cause progressive and severe loss of vision by altering the anatomy and/or function of the retina. Currently, there is no cure, but research is being conducted to find ways of treating these conditions in the coming years through gene and cell therapies.
These conditions can cause damage to the photoreceptor cells, either predominantly the cones (responsible for detailed vision and color), rods (responsible for night and peripheral vision), or both at the same time. This is the case in Stargardt disease, retinitis pigmentosa, or cone-rod dystrophy, respectively.
There are also certain hereditary dystrophies, such as juvenile retinoschisis, familial exudative vitreoretinopathy, and Stickler syndrome, where vitreous and retinal abnormalities occur. In others, such as choroideremia, the underlying problem is in the choroid, the layer below the retina.
Most retinal dystrophies are diseases located exclusively in the eye, but they can sometimes be associated with extraocular manifestations (such as Usher syndrome, Bardet-Biedl syndrome), in which case they are referred to as syndromic retinal dystrophies.
Due to their low prevalence, retinal dystrophies are considered minority or rare diseases (affecting less than 1 in 2,000 people).
What Causes Retinal Dystrophies?
Retinal dystrophies are genetic in origin, meaning they can be passed from generation to generation through different types of inheritance.
- Dominant inheritance: All generations of a family are usually affected because the carriers of the mutation responsible for the disease are themselves affected. This is typically passed on to about 50% of descendants, as in Best disease.
- Recessive inheritance: Only family members in one generation are typically affected because carriers of one mutation are healthy, while individuals who inherit two mutations in the same gene develop the disease. This is the case with Stargardt disease.
- X-linked inheritance: Only men in the family are affected, but women can be carriers of the mutation and pass it on to their sons with a 50% probability. Choroideremia is an example of a condition inherited in this manner.
Retinitis pigmentosa, the most common retinal dystrophy, is an example of a condition that can be transmitted through all three inheritance patterns, depending on the gene involved.
The genetics of retinal dystrophies is complex: the same condition can be caused by several genes, and simultaneously, the same gene can be associated with different diseases. To date, more than 250 genes associated with retinal dystrophies have been described, but many more are likely yet to be identified.
How Can Retinal Dystrophies Be Prevented?
The genetic information contained in the DNA of each person determines whether a retinal dystrophy will develop, so these hereditary conditions cannot be prevented. However, one aspect that can make a difference is early detection by specialist ophthalmologists through a full eye check-up, including a detailed medical history and thorough examination of the retina, as well as the use of complementary techniques such as OCT, autofluorescence, and electrophysiological tests.