DALRD3 (DALR anticodon binding domain containing 3) is a tRNA-binding protein essential for post-transcriptional RNA modification. Functionally, DALRD3 forms a complex with the METTL2 methyltransferase to facilitate recognition and targeting of specific arginine tRNA isoacceptors (tRNA-Arg(CCU) and tRNA-Arg(UCU)) for 3-methylcytosine (m3C) modification in the anticodon loop 1. DALRD3-deficient cells exhibit nearly complete loss of m3C modification in these arginine tRNA species 1. Clinically, DALRD3 dysfunction is associated with developmental and epileptic encephalopathy. Homozygous nonsense mutations and missense variants (R517C) in DALRD3 impair tRNA modification capacity and cause developmental delay, cognitive deficiencies, and early-onset multifocal epilepsy 12. These findings underscore DALRD3-dependent tRNA modification as crucial for proper neurological development 1. Beyond neurological disease, DALRD3 has been identified as a candidate causal gene in obsessive-compulsive disorder through genome-wide association studies combining 53,660 cases and over 2 million controls 34. Additionally, DALRD3 expression is differentially regulated in anorexia nervosa and shows reduced brain expression levels in insomnia patients 56.