LIPJ (lipase family member J) is an acid lipase belonging to the AB hydrolase superfamily that catalyzes triglyceride hydrolysis 1. Originally identified as a testis-specific acid lipase 1, LIPJ exhibits lipase activity and participates in lipid metabolic processes. The enzyme is a member of a mammalian acid lipase gene family that arose through gene duplication events prior to eutherian evolution 1. LIPJ has been extensively characterized through protein engineering studies. The Bacillus LipJ variant exhibits alkaline pH optimum and broad substrate specificity 23. Engineering efforts have successfully modified its catalytic properties: a Gln121Arg point mutation increased temperature optimum from 37°C to 50°C with six-fold enhanced half-life at elevated temperatures 2, while an Ile137Met substitution conferred psychrophilic behavior, enabling optimal activity at 20°C 3. Clinically, LIPJ is implicated in gestational diabetes mellitus (GDM) pathogenesis. Genome-wide association studies in Chinese women identified LIPJ among genes significantly enriched in lipolysis-related pathways associated with GDM risk 4. These findings suggest energy metabolism and lipolysis may play important roles in GDM aetiology, warranting further molecular investigation 4.