A mutation linked to macular dystrophy found for the first time

The British Journal of Ophthalmology publishes the finding of this new mutation, found in 12 Kuwaiti families with macular dystrophy, in a gene until now associated with retinitis pigmentosa.

research team

Researchers from the IMO Foundation have located, for the first time, a mutation in the RP1 gene - until now exclusively linked to retinitis pigmentosa - which causes macular dystrophy, a type of hereditary disease of the retina that causes blindness in the medium and long term and doesn’t have treatment. This finding was recently published in the British Journal of Ophthalmology.

Since the discovery of the RP1 gene 20 years ago, it has only been associated with retinitis pigmentosa - a retinal pathology that mainly affects the photoreceptor cells known as rods, causing loss of peripheral vision, and which may be linked to one of the nearly 100 genes so far identified as possible causes of the pathology.

30 genes associated with macular dystrophy

In the case of macular dystrophy, about 30 genes are known to be capable of triggering this disease, which affects another type of retinal cells, the cones, and leads to loss of central vision. Precisely, the finding of the IMO Foundation research team has arisen from the search for the mutation that causes several cases of macular dystrophy, whose origin was not found in any of these 30 known genes.

Hereditary retinal dystrophies affect the retinal photoreceptor cells, either primarily the cones (as in macular dystrophy), the rods (as in retinitis pigmentosa), or both types at once.

To find the mutation, 280 genes related to all retinal dystrophies (retinitis pigmentosa, cone and rod dystrophy, Stargardt's disease, Leber's congenital amaurosis, etc.) were examined. The IMO Foundation team analyzed all these genes in a hundred families, including 12 Kuwaiti ones, locating, in this dozen, a common pathogenic variant in the RP1 gene, which causes macular dystrophy. According to Dr. Esther Pomares, head of the team behind the discovery, the 12 Kuwaiti families "have the same haplotype (combination of alleles) which is inherited in bulk, together with the RP1 gene, where the mutation we have discovered occurs".

Common ancestor

This fact shows that all the people concerned share a common ancestor, the head of a tribe whose descendants comprise about 250,000 Kuwaitis, which has surprised the group of researchers. "This is a cultural phenomenon far removed from the current western world and one of its greatest historical exponents is Genghis Khan, a Mongolian warrior and conqueror from the 13th century, to whom a long lineage is attributed, having sired hundreds of sons, some of whom in turn left a prolific offspring," explains Dr. Victor Abad of the IMO Foundation team.

From the scientific point of view, the discovery will allow to extend the knowledge of the molecular bases of macular dystrophies and opens the door to a future treatment, with genetic or cellular therapies, of the patients with this affectation whose genetic origin had not been found until now. "We now know that depending on which part of the RP1 gene is altered, cones can also be affected, and not just the rods, as it was believed until now," says Dr. Pomares.

Teamwork

The article on this achievement, published in the British Journal of Ophthalmology, is signed by the members of the IMO Department of Genetics -Dr. Esther Pomares, Dr. Víctor Abad, Dr. Marina Riera, Sheila Ruiz and Pilar Méndez-, as well as the ophthalmologists, retina specialists of IMO, Dr. Borja Corcóstegui and Dr. Rafael Navarro.