Determinants of Disease Penetrance in PRPF31-Associated Retinopathy

Samuel Mclenachan,Danial Roshandel,Fred K Chen,Shang-Chih Chen,Tina M Lamey,Zhiqin Huang,Mary S Attia,Sue Fletcher,Dan Zhang,Khine Zaw,Xiao Zhang,Alanis Lima,Terri L Mclaren,Luke Jennings,Janya Grainok,John De Roach,Rachael C Heath Jeffery,Sang Yoon Moon,Jennifer A Thompson

doi:10.3390/genes12101542

Abstract

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 correlate with 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 lengths was present in NPC RPE monolayers. Our results indicate that RP11 non-penetrance is associated with the inheritance of a 4-copy MSR1 repeat, but not with CNOT3 polymorphisms.

Highlights

Inherited retinal diseases (IRDs) are the most common cause of blindness in the working-age population [1,2]
Genotyping of the minisatellite repeat element 1 (MSR1) repeat element demonstrated the inheritance of a homozygous 3-copy MSR1 repeat element (3/3 genotype) in all affected patients, while three of the five non-penetrant carriers (NPCs) carried a 4-copy repeat element (3/4 genotype) (Table 1). These results demonstrate disease non–penetrance is associated with the inheritance of pre-mRNA processing factor 31 (PRPF31) alleles containing 4-copy MSR1 repeats in their promoter region
PRPF31 expression in an Retinitis pigmentosa 11 (RP11) family by measuring expression levels in fibroblasts as well as induced pluripotent stem cells (iPSC)-derived retinal cells. Our results showed both PRPF31 and CNOT3 expression were reduced in fibroblasts, retinal organoids (ROs) and retinal pigment epithelium (RPE) derived from affected RP11 patients and an unaffected

Summary

Introduction

Inherited retinal diseases (IRDs) are the most common cause of blindness in the working-age population [1,2]. RP11, caused by mutations in the pre-mRNA processing factor 31 (PRPF31) gene (OMIM #600138) accounts for 5–10% of all the autosomal dominant forms of RP worldwide [4,5,6]. The carriers of pathogenic PRPF31 mutations can exhibit non-penetrance despite the manifestation of a severe RP phenotype in other family members carrying the same mutation [7,8]. Mutations in this gene lead to non-syndromic RP despite the ubiquitous expression of PRPF31 and its important role in splicing in all cell types. A deeper understanding of the molecular mechanisms underlying non-penetrance and non-syndromic manifestations of RP11 are essential for the development of safe and effective therapy for RP11

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Discussion

Conclusion