Mutations in REEP6 Cause Autosomal-Recessive Retinitis Pigmentosa.

Retinitis pigmentosa (RP) is the most frequent form of inherited retinal dystrophy. RP is genetically heterogeneous and the genes identified to date encode proteins involved in a wide range of functional pathways, including photoreceptor development, phototransduction, the retinoid cycle, cilia, and outer segment development. Here we report the identification of biallelic mutations in Receptor Expression Enhancer Protein 6 (REEP6) in seven individuals with autosomal-recessive RP from five unrelated families. REEP6 is a member of the REEP/Yop1 family of proteins that influence the structure of the endoplasmic reticulum but is relatively unstudied. The six variants identified include three frameshift variants, two missense variants, and a genomic rearrangement that disrupts exon 1. Human 3D organoid optic cups were used to investigate REEP6 expression and confirmed the expression of a retina-specific isoform REEP6.1, which is specifically affected by one of the frameshift mutations. Expression of the two missense variants (c.383C>T [p.Pro128Leu] and c.404T>C [p.Leu135Pro]) and the REEP6.1 frameshift mutant in cultured cells suggest that these changes destabilize the protein. Furthermore, CRISPR-Cas9-mediated gene editing was used to produce Reep6 knock-in mice with the p.Leu135Pro RP-associated variant identified in one RP-affected individual. The homozygous knock-in mice mimic the clinical phenotypes of RP, including progressive photoreceptor degeneration and dysfunction of the rod photoreceptors. Therefore, our study implicates REEP6 in retinal homeostasis and highlights a pathway previously uncharacterized in retinal dystrophy. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Citation

Gavin Arno, Smriti A Agrawal, Aiden Eblimit, James Bellingham, Mingchu Xu, Feng Wang, Christina Chakarova, David A Parfitt, Amelia Lane, Thomas Burgoyne, Sarah Hull, Keren J Carss, Alessia Fiorentino, Matthew J Hayes, Peter M Munro, Ralph Nicols, Nikolas Pontikos, Graham E Holder, UKIRDC, Chinwe Asomugha, F Lucy Raymond, Anthony T Moore, Vincent Plagnol, Michel Michaelides, Alison J Hardcastle, Yumei Li, Catherine Cukras, Andrew R Webster, Michael E Cheetham, Rui Chen. Mutations in REEP6 Cause Autosomal-Recessive Retinitis Pigmentosa. American journal of human genetics. 2016 Dec 01;99(6):1305-1315

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PMID: 27889058

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