tRNA Methyltransferase Defects and Intellectual Disability

In all organisms, transfer RNA (tRNA) molecules are required to undergo post-transcriptional modifications at different levels in order to convert into mature tRNAs. These modifications are critical for many aspects of tRNA function and structure, such as translational efficiency, flexibility, codon-anticodon interaction, stability, and fidelity. Up to now, over 100 modified nucleosides have been identified in tRNAs from all domains of life. Post-transcriptional modifications include different chemical processes such as methylation, deamination, or acetylation, with methylation reactions as the most common. tRNA methyltransferases are a family of enzymes involved in the post-transcriptional methylation of tRNA bases. Recent studies have reported different human diseases resulting from defects in tRNA methyltransferase activity, including cancer, diabetes and neurological disorders such as intellectual disability (ID). In this article, we focused on biological function and characterization of tRNA methyltransferases associated with ID in order to explain how functional disruption of tRNA methyltransferases could lead to ID phenotype.