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WARS2 mutations cause dopa-responsive early-onset parkinsonism and progressive myoclonus ataxia.

Parkinsonism Relat Disord. 2021 Dec 2;94:54-61. doi: 10.1016/j.parkreldis.2021.11.030. Epub ahead of print. PMID: 34890876.

Authors/Editors: Skorvanek M, Rektorova I, Mandemakers W, Wagner M, Steinfeld R, Orec L, Han V, Pavelekova P, Lackova A, Kulcsarova K, Ostrozovicova M, Gdovinova Z, Plecko B, Brunet T, Berutti R, Kuipers DJS, Boumeester V, Havrankova P, Tijssen MAJ, Kaiyrzhanov R, Rizig M, Houlden H, Winkelmann J, Bonifati V, Zech M, Jech R.
Publication Date: 2021

Abstract


Introduction
Sixteen subjects with biallelic WARS2 variants encoding the tryptophanyl mitochondrial aminoacyl-tRNA synthetase, presenting with a neonatal- or infantile-onset mitochondrial disease, have been reported to date. Here we present six novel cases with WARS2-related diseases and expand the spectrum to later onset phenotypes including dopa-responsive early-onset parkinsonism and progressive myoclonus-ataxia.

Methods
Six individuals from four families underwent whole-exome sequencing within research and diagnostic settings. Following the identification of a genetic defect, in-depth phenotyping and protein expression studies were performed.

Results
A relatively common (gnomAD MAF = 0.0033) pathogenic p.(Trp13Gly) missense variant in WARS2 was detected in trans in all six affected individuals in combination with different pathogenic alleles (exon 2 deletion in family 1; p.(Leu100del) in family 2; p.(Gly50Asp) in family 3; and p.(Glu208*) in family 4). Two subjects presented with action tremor around age 10–12 years and developed tremor-dominant parkinsonism with prominent neuropsychiatric features later in their 20s. Two subjects presented with a progressive myoclonus-ataxia dominant phenotype. One subject presented with spasticity, choreo-dystonia, myoclonus, and speech problems. One subject presented with speech problems, ataxia, and tremor. Western blotting analyses in patient‐derived fibroblasts showed a markedly decreased expression of the full‐length WARS2 protein in both subjects carrying p.(Trp13Gly) and an exon-2 deletion in compound heterozygosity.

Conclusions
This study expands the spectrum of the disease to later onset phenotypes of early-onset tremor-dominant parkinsonism and progressive myoclonus-ataxia phenotypes.

 

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