ADAT1 (adenosine deaminase tRNA specific 1) is a tRNA-specific adenosine deaminase that catalyzes post-transcriptional RNA modification. The enzyme specifically converts adenosine-37 to inosine in the anticodon loop of tRNA-Ala through hydrolytic deamination 1. This modification is part of the unique A(37) to m(1)I(37) conversion essential for eukaryotic tRNA-Ala function 2. ADAT1 is structurally related to the ADAR family of RNA editing enzymes but functions exclusively on tRNA substrates rather than pre-mRNA 3. The enzyme requires inositol hexakisphosphate (IP6) as a cofactor for both in vitro and in vivo catalytic activity 4. Human ADAT1 is encoded from a single-copy gene on chromosome 16-24, clustered with two tRNA synthetases (KARS and AARS), suggesting coordinated regulation of tRNA metabolism 1. Beyond its canonical tRNA modification role, ADAT1 has emerged as a disease-relevant gene. It was identified as a reproduction-related candidate gene with nonsynonymous polymorphisms in reproductive tissues 5, and recent exome-wide association studies identified ADAT1 variants as susceptibility loci for early-onset coronary artery disease in Japanese populations 6, suggesting broader physiological significance beyond tRNA modification.