Determinants of Disease Penetrance in PRPF31-Associated Retinopathy

Retinitis pigmentosa 11 (RP11) is caused by dominant mutations in PRPF31, however a significant proportion of mutation carriers do not develop retinopathy. Here, we investigated the relationship between CNOT3 polymorphism, MSR1 repeat copy number and disease penetrance in RP11 patients and non-penetrant carriers (NPCs). We further characterized PRPF31 and CNOT3 expression in fibroblasts from eight RP11 patients and one NPC from a family carrying the c.1205C > T variant. Retinal organoids (ROs) and retinal pigment epithelium (RPE) were differentiated from induced pluripotent stem cells derived from RP11 patients, an NPC and a control subject. All RP11 patients were homozygous for the 3-copy MSR1 repeat in the PRPF31 promoter, while 3/5 NPCs carried a 4-copy MSR1 repeat. The CNOT3 rs4806718 genotype did not correlatewith disease penetrance. PRFP31 expression declined with age in adult cadaveric retina. PRPF31 and CNOT3 expression was reduced in RP11 fibroblasts, RO and RPE compared with controls. Both RP11 and NPC RPE displayed shortened primary cilia compared with controls, however a subpopulation of cells with normal cilia lengthswas present inNPC RPEmonolayers. Our results indicate that RP11 non-penetrance is associated with the inheritance of a 4-copyMSR1 repeat, but not with CNOT3 polymorphisms.

Automated summary

The non-penetrance of RP11 is associated with inheritance of a 4-copy MSR1 repeat, but not with CNOT3 polymorphisms.