JIMD Reports (May 2023)

Severe neonatal onset neuroregression with paroxysmal dystonia and apnoea: Expanding the phenotypic and genotypic spectrum of CARS2‐related mitochondrial disease

  • Jessie Poquérusse,
  • Melinda Nolan,
  • David R. Thorburn,
  • Johan L. K. Van Hove,
  • Marisa W. Friederich,
  • Donald R. Love,
  • Juliet Taylor,
  • Christopher A. Powell,
  • Michal Minczuk,
  • Russell G. Snell,
  • Klaus Lehnert,
  • Emma Glamuzina,
  • Jessie C. Jacobsen

DOI
https://doi.org/10.1002/jmd2.12360
Journal volume & issue
Vol. 64, no. 3
pp. 223 – 232

Abstract

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Abstract Disorders of mitochondrial function are a collectively common group of genetic diseases in which deficits in core mitochondrial translation machinery, including aminoacyl tRNA synthetases, are key players. Biallelic variants in the CARS2 gene (NM_024537.4), which encodes the mitochondrial aminoacyl‐tRNA synthetase for cysteine (CARS2, mt‐aaRScys; MIM*612800), result in childhood onset epileptic encephalopathy and complex movement disorder with combined oxidative phosphorylation deficiency (MIM#616672). Prior to this report, eight unique pathogenic variants in the CARS2 gene had been reported in seven individuals. Here, we describe a male who presented in the third week of life with apnoea. He rapidly deteriorated with paroxysmal dystonic crises and apnoea resulting in death at 16 weeks. He had no evidence of seizure activity or multisystem disease and had normal brain imaging. Skeletal muscle biopsy revealed a combined disorder of oxidative phosphorylation. Whole‐exome sequencing identified biallelic variants in the CARS2 gene: one novel (c.1478T>C, p.Phe493Ser), and one previously reported (c.655G>A, p.Ala219Thr; rs727505361). Northern blot analysis of RNA isolated from the patient's fibroblasts confirmed a clear defect in aminoacylation of the mitochondrial tRNA for cysteine (mt‐tRNACys). To our knowledge, this is the earliest reported case of CARS2 deficiency with severe, early onset dystonia and apnoea, without epilepsy.

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