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Schoonen M, Smuts I, Louw R, Elson JL, van Dyk E, Jonck LM, Rodenburg RJT, van der Westhuizen FH. Panel-Based Nuclear and Mitochondrial Next-Generation Sequencing Outcomes of an Ethnically Diverse Pediatric Patient Cohort with Mitochondrial Disease. J Mol Diagn 2019; 21:503-513. [PMID: 30872186 DOI: 10.1016/j.jmoldx.2019.02.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 01/08/2019] [Accepted: 02/06/2019] [Indexed: 12/31/2022] Open
Abstract
Mitochondrial disease (MD) is a group of rare inherited disorders with clinical heterogeneous phenotypes. Recent advances in next-generation sequencing (NGS) allow for rapid genetic diagnostics in patients who experience MD, resulting in significant strides in determining its etiology. This, however, has not been the case in many patient populations. We report on a molecular diagnostic study using mitochondrial DNA and targeted nuclear DNA (nDNA) NGS of an extensive cohort of predominantly sub-Saharan African pediatric patients with clinical and biochemically defined MD. Patients in this novel cohort presented mostly with muscle involvement (73%). Of the original 212 patients, a muscle respiratory chain deficiency was identified in 127 cases. Genetic analyses were conducted for these 127 cases based on biochemical deficiencies, for both mitochondrial (n = 123) and nDNA using panel-based NGS (n = 86). As a pilot investigation, whole-exome sequencing was performed in a subset of African patients (n = 8). These analyses resulted in the identification of a previously reported pathogenic mitochondrial DNA variant and seven pathogenic or likely pathogenic nDNA variants (ETFDH, SURF1, COQ6, RYR1, STAC3, ALAS2, and TRIOBP), most of which were identified via whole-exome sequencing. This study contributes to knowledge of MD etiology in an understudied, ethnically diverse population; highlights inconsistencies in genotype-phenotype correlations; and proposes future directions for diagnostic approaches in such patient populations.
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Affiliation(s)
- Maryke Schoonen
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University, Potchefstroom, South Africa
| | - Izelle Smuts
- Department of Paediatrics and Child Health, Steve Biko Academic Hospital, University of Pretoria, Pretoria, South Africa
| | - Roan Louw
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University, Potchefstroom, South Africa
| | - Joanna L Elson
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University, Potchefstroom, South Africa; Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Etresia van Dyk
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University, Potchefstroom, South Africa
| | - Lindi-Maryn Jonck
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University, Potchefstroom, South Africa
| | - Richard J T Rodenburg
- Department of Pediatrics, Radboudumc Amalia Childrens Hospital, Radboud Center for Mitochondrial Medicine, Nijmegen, the Netherlands
| | - Francois H van der Westhuizen
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University, Potchefstroom, South Africa.
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