Suzanne de Bruijn

19 General introduction 1. Sensory perception of light stimulus (GO:0050953) 2. Visual perception (GO:0007601) 3. Cilium assembly (GO:0060271) 4. Cilium organization (GO:0044782) 5. Detection of visible light (GO:0009584) 6. Plasma membrane bounded cell projection assembly (GO:0120031) 7. Detection of light stimulus involved in sensory perception (GO:0050962) 8. Organelle assembly (GO:0070925) 9. Ciliary basal body-plasma membrane docking (GO:0097711) 10. Phototransduction (GO:0007603) Figure 2. Biological processes linked to retinal dystrophy-associated genes. A gene ontology (GO) enrichment analysis was performed to visualize biochemical processes that are significantly associated with retinal dystrophies (RD). The top 10 of biochemical processes that show enrichment for RD-associated proteins are indicated. The length of the colored bars represents the association strength (-log10(p-value)). GO-term enrichment analysis was performed using Enrichr 14 and based on the GO biological processes term list (2018). RD-associated genes (n=271) were extracted from the RetNet website (May 2021). 13 Non-syndromic retinitis pigmentosa Retinitis pigmentosa (RP) is the most common RD, with an incidence of 1 in 4,000 individuals. 15 It is caused by the progressive degeneration of the rod photoreceptor cells and the RPE. The classical RP phenotype involves night blindness in adolescence, followed by the loss of peripheral vision in young adulthood leading to tunnel vison or complete visual loss in some cases. 16 In case of legal blindness, the peripheral vision is less than 20 degrees. However, as most inherited RDs, RP is a highly variable disorder and there are ample examples of individuals that remain asymptomatic until mid- adulthood. 8 RP can be clinically diagnosed by performing imaging techniques and visual acuity measurements. Fundus photography, providing an image of the back of the eye, can be performed to check for the presence of characteristic RP-associated hallmarks: bone spicule pigmentation (predominantly midperipheral), attenuation of the retinal vessels and a waxy color of the optic nerve. 15 Fundus autofluorescent (FAF) imaging can, among other characteristics, reveal a hyperautofluorescent ring that represents the transition zone between normal and abnormal retinal tissue. Optical coherence tomography