Cysteinyl-tRNA Synthetase Mutations Cause a Multi-System, Recessive Disease That Includes Microcephaly, Developmental Delay, and Brittle Hair and Nails

Am J Hum Genet. 2019 Mar 7;104(3):520-529. doi: 10.1016/j.ajhg.2019.01.006. Epub 2019 Feb 26.


Aminoacyl-tRNA synthetases (ARSs) are essential enzymes responsible for charging tRNA molecules with cognate amino acids. Consistent with the essential function and ubiquitous expression of ARSs, mutations in 32 of the 37 ARS-encoding loci cause severe, early-onset recessive phenotypes. Previous genetic and functional data suggest a loss-of-function mechanism; however, our understanding of the allelic and locus heterogeneity of ARS-related disease is incomplete. Cysteinyl-tRNA synthetase (CARS) encodes the enzyme that charges tRNACys with cysteine in the cytoplasm. To date, CARS variants have not been implicated in any human disease phenotype. Here, we report on four subjects from three families with complex syndromes that include microcephaly, developmental delay, and brittle hair and nails. Each affected person carries bi-allelic CARS variants: one individual is compound heterozygous for c.1138C>T (p.Gln380) and c.1022G>A (p.Arg341His), two related individuals are compound heterozygous for c.1076C>T (p.Ser359Leu) and c.1199T>A (p.Leu400Gln), and one individual is homozygous for c.2061dup (p.Ser688Glnfs2). Measurement of protein abundance, yeast complementation assays, and assessments of tRNA charging indicate that each CARS variant causes a loss-of-function effect. Compared to subjects with previously reported ARS-related diseases, individuals with bi-allelic CARS variants are unique in presenting with a brittle-hair-and-nail phenotype, which most likely reflects the high cysteine content in human keratins. In sum, our efforts implicate CARS variants in human inherited disease, expand the locus and clinical heterogeneity of ARS-related clinical phenotypes, and further support impaired tRNA charging as the primary mechanism of recessive ARS-related disease.

Keywords: aminoacyl-tRNA synthetase; cysteinyl-tRNA synthetase; developmental delay; microcephaly; peripheral neuropathy; recessive disease.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Amino Acid Sequence
  • Amino Acyl-tRNA Synthetases / genetics*
  • Charcot-Marie-Tooth Disease / enzymology
  • Charcot-Marie-Tooth Disease / etiology*
  • Charcot-Marie-Tooth Disease / pathology
  • Developmental Disabilities / enzymology
  • Developmental Disabilities / etiology*
  • Developmental Disabilities / pathology
  • Female
  • Genes, Recessive
  • Genetic Predisposition to Disease
  • Hair Diseases / enzymology
  • Hair Diseases / etiology*
  • Hair Diseases / pathology
  • Humans
  • Male
  • Microcephaly / enzymology
  • Microcephaly / etiology*
  • Microcephaly / pathology
  • Mutation*
  • Nail Diseases / enzymology
  • Nail Diseases / etiology*
  • Nail Diseases / pathology
  • Pedigree
  • Phenotype
  • Prognosis
  • Sequence Homology
  • Young Adult


  • Amino Acyl-tRNA Synthetases
  • cysteinyl-tRNA synthetase