Mutations of the aminoacyl-tRNA-synthetases SARS and WARS2 are implicated in the etiology of autosomal recessive intellectual disability

Hum Mutat. 2017 Jun;38(6):621-636. doi: 10.1002/humu.23205. Epub 2017 Mar 23.

Abstract

Intellectual disability (ID) is the hallmark of an extremely heterogeneous group of disorders that comprises a wide variety of syndromic and non-syndromic phenotypes. Here, we report on mutations in two aminoacyl-tRNA synthetases that are associated with ID in two unrelated Iranian families. In the first family, we identified a homozygous missense mutation (c.514G>A, p.Asp172Asn) in the cytoplasmic seryl-tRNA synthetase (SARS) gene. The mutation affects the enzymatic core domain of the protein and impairs its enzymatic activity, probably leading to reduced cytoplasmic tRNASer concentrations. The mutant protein was predicted to be unstable, which could be substantiated by investigating ectopic mutant SARS in transfected HEK293T cells. In the second family, we found a compound heterozygous genotype of the mitochondrial tryptophanyl-tRNA synthetase (WARS2) gene, comprising a nonsense mutation (c.325delA, p.Ser109Alafs*15), which very likely entails nonsense-mediated mRNA decay and a missense mutation (c.37T>G, p.Trp13Gly). The latter affects the mitochondrial localization signal of WARS2, causing protein mislocalization. Including AIMP1, which we have recently implicated in the etiology of ID, three genes with a role in tRNA-aminoacylation are now associated with this condition. We therefore suggest that the functional integrity of tRNAs in general is an important factor in the development and maintenance of human cognitive functions.

Keywords: SARS; WARS2; aminoacyl-tRNA-synthetase; aminoacylation; brain; cognition; intellectual disability; tRNA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Amino Acyl-tRNA Synthetases / genetics*
  • Child
  • Cytokines / genetics
  • Female
  • HEK293 Cells
  • Homozygote
  • Humans
  • Intellectual Disability / genetics*
  • Intellectual Disability / pathology
  • Iran
  • Male
  • Mutation, Missense / genetics
  • Neoplasm Proteins / genetics
  • Nonsense Mediated mRNA Decay / genetics*
  • Pedigree
  • RNA-Binding Proteins / genetics

Substances

  • Cytokines
  • Neoplasm Proteins
  • RNA-Binding Proteins
  • small inducible cytokine subfamily E, member 1
  • Amino Acyl-tRNA Synthetases