Inherited retinal dystrophies

Recessive inherited retinal dystrophies are ideal targets for gene therapy

HORAMA develops rAAV-based gene therapy products for inherited ophthalmic diseases such as monogenic retinal dystrophies for which no approved treatment exists. 

Inherited retinal dystrophies are rare ophthalmic pathologies that can be divided into two groups: pigmentary retinopathies, which include retinitis pigmentosa and Leber congenital amaurosis (over 3.5 million patients worldwide), and macular dystrophies (over 1.6 million patients worldwide). While multiple genes are implicated in each of these groups, within each patient or family only one causative gene is involved. 

Rétinitis pigmentosa can be inherited in an autosomal dominant, autosomal recessive (60% of cases of RP), or X-linked manner. Genetic counselling should be provided to affected individuals and their families once the mode of inheritance has been identified by analysis of the family history or molecular testing (Source: Orphanet). At 50% of all retinal dystrophies and prevalence ranges between 1/1,000 (Africa, Oceania, Asia) and 1/4,000 in other countries, retinitis pigmentosa is the most common form of inherited retinal dystrophy. There are no approved treatments for retinitis pigmentosa currently available.

Given their monogenic nature and the conveniences of subretinal gene therapy administration, retinal dystrophies are ideal targets for rAAV gene therapy.

Pigmentary retinopathies are characterised by

Decreased vision in dim light, visual field constriction, and decreased visual acuity make daily activities such as moving or reading more difficult.

Non-syndromic retinitis pigmentosa is the most common disease in this group (60% of cases). Leber congenital amaurosis accounts for 5% of cases.

Maculopathies are
characterised by

Decreased central visual acuity make critical skills like facial recognition and reading more difficult. Stargardt disease is the most common disease in this group (50% of cases)