SSBP1 mutations in dominant optic atrophy with variable retinal degeneration

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Item Type:	Article
Title:	SSBP1 mutations in dominant optic atrophy with variable retinal degeneration
Creators Name:	Jurkute, N., Leu, C., Pogoda, H.M., Arno, G., Robson, A.G., Nürnberg, G., Altmüller, J., Thiele, H., Motameny, S., Toliat, M.R., Powell, K., Höhne, W., Michaelides, M., Webster, A.R., Moore, A.T., Hammerschmidt, M., Nürnberg, P., Yu-Wai-Man, P. and Votruba, M.
Abstract:	OBJECTIVE: Autosomal dominant optic atrophy (ADOA) starts in early childhood with loss of visual acuity and color vision deficits. OPA1 mutations are responsible for the majority of cases, but in a portion of patients with a clinical diagnosis of ADOA, the cause remains unknown. This study aimed to identify novel ADOA-associated genes and explore their causality. METHODS: Linkage analysis and sequencing were performed in multigeneration families and unrelated patients to identify disease-causing variants. Functional consequences were investigated in silico and confirmed experimentally using the zebrafish model. RESULTS: We defined a new ADOA locus on 7q33-q35 and identified 3 different missense variants in SSBP1 (NM_001256510.1; c.113G>A [p.(Arg38Gln)], c.320G>A [p.(Arg107Gln)] and c.422G>A [p.(Ser141Asn)]) in affected individuals from 2 families and 2 singletons with ADOA and variable retinal degeneration. The mutated arginine residues are part of a basic patch that is essential for single-strand DNA binding. The loss of a positive charge at these positions is very likely to lower the affinity of SSBP1 for single-strand DNA. Antisense-mediated knockdown of endogenous ssbp1 messenger RNA (mRNA) in zebrafish resulted in compromised differentiation of retinal ganglion cells. A similar effect was achieved when mutated mRNAs were administered. These findings point toward an essential role of ssbp1 in retinal development and the dominant-negative nature of the identified human variants, which is consistent with the segregation pattern observed in 2 multigeneration families studied. INTERPRETATION: SSBP1 is an essential protein for mitochondrial DNA replication and maintenance. Our data have established pathogenic variants in SSBP1 as a cause of ADOA and variable retinal degeneration.
Keywords:	Cell Differentiation, Cultured Cells, DNA-Binding Proteins, Gene Knockdown Techniques, Genetic Linkage, Genetic Predisposition to Disease, Mitochondrial Proteins, Missense Mutation, Autosomal Dominant Optic Atrophy, Pedigree, Messenger RNA, Retinal Degeneration, Animals, Mice, Zebrafish
Source:	Annals of Neurology
ISSN:	0364-5134
Publisher:	Wiley
Volume:	86
Number:	3
Page Range:	368-383
Date:	September 2019
Official Publication:	https://doi.org/10.1002/ana.25550
PubMed:	View item in PubMed

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