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Biallelic variants in WARS2 encoding mitochondrial tryptophanyl-tRNA synthase in six individuals with mitochondrial encephalopathy

Lookup NU author(s): Professor Joris VeltmanORCiD

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Abstract

© 2017 Wiley Periodicals, Inc. Mitochondrial protein synthesis involves an intricate interplay between mitochondrial DNA encoded RNAs and nuclear DNA encoded proteins, such as ribosomal proteins and aminoacyl-tRNA synthases. Eukaryotic cells contain 17 mitochondria-specific aminoacyl-tRNA synthases. WARS2 encodes mitochondrial tryptophanyl-tRNA synthase (mtTrpRS), a homodimeric class Ic enzyme (mitochondrial tryptophan-tRNA ligase; EC 6.1.1.2). Here, we report six individuals from five families presenting with either severe neonatal onset lactic acidosis, encephalomyopathy and early death or a later onset, more attenuated course of disease with predominating intellectual disability. Respiratory chain enzymes were usually normal in muscle and fibroblasts, while a severe combined respiratory chain deficiency was found in the liver of a severely affected individual. Exome sequencing revealed rare biallelic variants in WARS2 in all affected individuals. An increase of uncharged mitochondrial tRNATrp and a decrease of mtTrpRS protein content were found in fibroblasts of affected individuals. We hereby define the clinical, neuroradiological, and metabolic phenotype of WARS2 defects. This confidently implicates that mutations in WARS2 cause mitochondrial disease with a broad spectrum of clinical presentation.

Publication metadata

Author(s): Wortmann SB, Timal S, Venselaar H, Wintjes LT, Kopajtich R, Feichtinger RG, Onnekink C, Muhlmeister M, Brandt U, Smeitink JA, Veltman JA, Sperl W, Lefeber D, Pruijn G, Stojanovic V, Freisinger P, v Spronsen F, Derks TGJ, Veenstra-Knol HE, Mayr JA, Rotig A, Tarnopolsky M, Prokisch H, Rodenburg RJ

Publication type: Article

Publication status: Published

Journal: Human Mutation

Year: 2017

Volume: 38

Issue: 12

Pages: 1786-1795

Print publication date: 01/12/2017

Online publication date: 06/10/2017

Acceptance date: 10/09/2017

ISSN (print): 1059-7794

ISSN (electronic): 1098-1004

Publisher: John Wiley and Sons Inc.

URL: https://doi.org/10.1002/humu.23340

DOI: 10.1002/humu.23340

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