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Lookup NU author(s): Dr Charlotte Alston, Lucie Taylor, Ruth Glasgow, Professor Bobby McFarlandORCiD, Professor Robert Taylor
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved. Isolated complex I deficiency is a common biochemical phenotype observed in pediatric mitochondrial disease and often arises as a consequence of pathogenic variants affecting one of the ∼65 genes encoding the complex I structural subunits or assembly factors. Such genetic heterogeneity means that application of next-generation sequencing technologies to undiagnosed cohorts has been a catalyst for genetic diagnosis and gene-disease associations. We describe the clinical and molecular genetic investigations of four unrelated children who presented with neuroradiological findings and/or elevated lactate levels, highly suggestive of an underlying mitochondrial diagnosis. Next-generation sequencing identified bi-allelic variants in NDUFA6, encoding a 15 kDa LYR-motif-containing complex I subunit that forms part of the Q-module. Functional investigations using subjects' fibroblast cell lines demonstrated complex I assembly defects, which were characterized in detail by mass-spectrometry-based complexome profiling. This confirmed a marked reduction in incorporated NDUFA6 and a concomitant reduction in other Q-module subunits, including NDUFAB1, NDUFA7, and NDUFA12. Lentiviral transduction of subjects' fibroblasts showed normalization of complex I. These data also support supercomplex formation, whereby the ∼830 kDa complex I intermediate (consisting of the P- and Q-modules) is in complex with assembled complex III and IV holoenzymes despite lacking the N-module. Interestingly, RNA-sequencing data provided evidence that the consensus RefSeq accession number does not correspond to the predominant transcript in clinically relevant tissues, prompting revision of the NDUFA6 RefSeq transcript and highlighting not only the importance of thorough variant interpretation but also the assessment of appropriate transcripts for analysis.
Author(s): Alston CL, Heidler J, Dibley MG, Kremer LS, Taylor LS, Fratter C, French CE, Glasgow RIC, Feichtinger RG, Delon I, Pagnamenta AT, Dolling H, Lemonde H, Aiton N, Bjornstad A, Henneke L, Gartner J, Thiele H, Tauchmannova K, Quaghebeur G, Houstek J, Sperl W, Raymond FL, Prokisch H, Mayr JA, McFarland R, Poulton J, Ryan MT, Wittig I, Henneke M, Taylor RW
Publication type: Article
Publication status: Published
Journal: American Journal of Human Genetics
Year: 2018
Volume: 103
Issue: 4
Pages: 592-601
Print publication date: 04/10/2018
Online publication date: 20/09/2018
Acceptance date: 22/08/2018
Date deposited: 26/10/2018
ISSN (print): 0002-9297
ISSN (electronic): 1537-6605
Publisher: Cell Press
URL: https://doi.org/10.1016/j.ajhg.2018.08.013
DOI: 10.1016/j.ajhg.2018.08.013
PubMed id: 30245030
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