Inherited retinal dystrophies

Recessive inherited retinal dystrophies are ideal targets for gene therapy

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

These 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). Retinitis pigmentosa is the most common form of inherited retinal dystrophy (50%), and no approved treatment is currently available.

The prevalence of retinitis pigmentosa ranges from 1/1,000 (Africa, Oceania, Asia) to 1/4,000 in other countries.

Pigmentary retinopathies are characterised by

Decreased vision in dim light, visual field constriction that hinders daily activities (e.g., movement), decreased visual acuity (reading difficulties).

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 (facial recognition and reading difficulties). Stargardt disease is the most common disease in this group (50% of cases)