Bi-allelic Mutations in the Mitochondrial Ribosomal Protein MRPS2 Cause Sensorineural Hearing Loss, Hypoglycemia, and Multiple OXPHOS Complex Deficiencies

Thatjana Gardeitchik, Miski Mohamed, Benedetta Ruzzenente, Daniela Karall, Sergio Guerrero-Castillo, Daisy Dalloyaux, Mariël van den Brand, Sanne van Kraaij, Ellyze van Asbeck, Zahra Assouline, Marlene Rio, Pascale de Lonlay, Sabine Scholl-Buergi, David F.G.J. Wolthuis, Alexander Hoischen, Richard J. Rodenburg, Wolfgang Sperl, Zsolt Urban, Ulrich Brandt, Johannes A. MayrSunnie Wong, Arjan P.M. de Brouwer, Leo Nijtmans, Arnold Munnich, Agnès Rötig, Ron A. Wevers, Metodi D. Metodiev, Eva Morava

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

Biogenesis of the mitochondrial oxidative phosphorylation system, which produces the bulk of ATP for almost all eukaryotic cells, depends on the translation of 13 mtDNA-encoded polypeptides by mitochondria-specific ribosomes in the mitochondrial matrix. These mitoribosomes are dual-origin ribonucleoprotein complexes, which contain mtDNA-encoded rRNAs and tRNAs and ∼80 nucleus-encoded proteins. An increasing number of gene mutations that impair mitoribosomal function and result in multiple OXPHOS deficiencies are being linked to human mitochondrial diseases. Using exome sequencing in two unrelated subjects presenting with sensorineural hearing impairment, mild developmental delay, hypoglycemia, and a combined OXPHOS deficiency, we identified mutations in the gene encoding the mitochondrial ribosomal protein S2, which has not previously been implicated in disease. Characterization of subjects’ fibroblasts revealed a decrease in the steady-state amounts of mutant MRPS2, and this decrease was shown by complexome profiling to prevent the assembly of the small mitoribosomal subunit. In turn, mitochondrial translation was inhibited, resulting in a combined OXPHOS deficiency detectable in subjects’ muscle and liver biopsies as well as in cultured skin fibroblasts. Reintroduction of wild-type MRPS2 restored mitochondrial translation and OXPHOS assembly. The combination of lactic acidemia, hypoglycemia, and sensorineural hearing loss, especially in the presence of a combined OXPHOS deficiency, should raise suspicion for a ribosomal-subunit-related mitochondrial defect, and clinical recognition could allow for a targeted diagnostic approach. The identification of MRPS2 as an additional gene related to mitochondrial disease further expands the genetic and phenotypic spectra of OXPHOS deficiencies caused by impaired mitochondrial translation.

Original languageEnglish (US)
Pages (from-to)685-695
Number of pages11
JournalAmerican journal of human genetics
Volume102
Issue number4
DOIs
StatePublished - Apr 5 2018

Keywords

  • 2-oxoglutaric acid
  • combined OXPHOS complex deficiencies
  • complexome profiling
  • hearing loss
  • mitochondrial ribosomes
  • mitochondrial translation defect
  • wrinkly skin

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

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