1. Deficient activity of alanyl-tRNA synthetase underlies an autosomal recessive syndrome of progressive microcephaly, hypomyelination, and epileptic encephalopathy.
- Author
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Nakayama T, Wu J, Galvin-Parton P, Weiss J, Andriola MR, Hill RS, Vaughan DJ, El-Quessny M, Barry BJ, Partlow JN, Barkovich AJ, Ling J, and Mochida GH
- Subjects
- Amino Acid Sequence genetics, Aminoacylation genetics, Charcot-Marie-Tooth Disease genetics, Charcot-Marie-Tooth Disease pathology, Child, Preschool, Electroencephalography, Female, Humans, Infant, Lennox Gastaut Syndrome complications, Lennox Gastaut Syndrome diagnosis, Lennox Gastaut Syndrome pathology, Microcephaly diagnostic imaging, Microcephaly pathology, Mutation genetics, Protein Biosynthesis genetics, Siblings, Spasms, Infantile complications, Spasms, Infantile diagnostic imaging, Spasms, Infantile pathology, Spastic Paraplegia, Hereditary complications, Spastic Paraplegia, Hereditary pathology, Exome Sequencing, Alanine-tRNA Ligase genetics, Lennox Gastaut Syndrome genetics, Microcephaly genetics, Spasms, Infantile genetics, Spastic Paraplegia, Hereditary genetics
- Abstract
Aminoacyl-transfer RNA (tRNA) synthetases ligate amino acids to specific tRNAs and are essential for protein synthesis. Although alanyl-tRNA synthetase (AARS) is a synthetase implicated in a wide range of neurological disorders from Charcot-Marie-Tooth disease to infantile epileptic encephalopathy, there have been limited data on their pathogenesis. Here, we report loss-of-function mutations in AARS in two siblings with progressive microcephaly with hypomyelination, intractable epilepsy, and spasticity. Whole-exome sequencing identified that the affected individuals were compound heterozygous for mutations in AARS gene, c.2067dupC (p.Tyr690Leufs*3) and c.2738G>A (p.Gly913Asp). A lymphoblastoid cell line developed from one of the affected individuals showed a strong reduction in AARS abundance. The mutations decrease aminoacylation efficiency by 70%-90%. The p.Tyr690Leufs*3 mutation also abolished editing activity required for hydrolyzing misacylated tRNAs, thereby increasing errors during aminoacylation. Our study has extended potential mechanisms underlying AARS-related disorders to include destabilization of the protein, aminoacylation dysfunction, and defective editing activity., (© 2017 Wiley Periodicals, Inc.)
- Published
- 2017
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