ABHD1 (abhydrolase domain containing 1) is a 405-residue protein encoded by a nine-exon gene on chromosome 2.3 that contains a catalytic triad characteristic of serine proteases 1. The protein exhibits acetylesterase and monoacylglycerol lipase activities, participating in medium-chain fatty acid biosynthesis and catabolism [NCBI annotation]. ABHD1 shows tissue-specific expression patterns, with high levels in skeletal muscle and testis but low expression in spleen and fibroblasts 1. A critical function of ABHD1 involves mitochondrial tRNA modification: the protein acts as a dioxygenase that oxidizes m5C34 methylcytosine at the wobble position of mitochondrial tRNAMet to generate f5C34, an essential modification for proper mitochondrial translation of methionine codons 2. This modification allows the single mitochondrial tRNAMet to recognize different methionine-encoding codons, and ABHD1 depletion severely impairs mitochondrial translation 2. Additionally, ABHD1 interferes with intestinal stem cell proliferation and migration 3, and genetic variants in ABHD1 (rs2304678) are associated with increased susceptibility to Hirschsprung disease, particularly total colonic aganglionosis in Southern Chinese children 3. The shared polyadenylation signal with the SEC12 gene suggests unique regulation of ABHD1 expression 1.