IDI1 (isopentenyl-diphosphate delta isomerase 1) is a cytoplasmic enzyme that catalyzes the conversion of isopentenyl diphosphate (IPP) to dimethylallyl diphosphate (DMAPP), a critical step in the mevalonate pathway for cholesterol and isoprenoid biosynthesis 1. The enzyme functions through a 1,3-allylic rearrangement mechanism and is localized in both cytosol and peroxisomes. IDI1 plays significant roles in pathological conditions, particularly in cardiovascular and metabolic diseases. In atrial myocytes subjected to mechanical stress, IDI1 upregulation contributes to lipotoxic myopathy and atrial enlargement in mitral regurgitation patients 2. The gene is also implicated in non-alcoholic steatohepatitis (NASH), where exercise training reduces hepatic lipid accumulation by downregulating IDI1 through decreased KMT2D-mediated histone methylation 3. Pathologically, IDI1 localizes to Lewy bodies in neurodegenerative diseases, potentially contributing to α-synuclein aggregation through cholesterol metabolite production 1. Additionally, IDI1 serves as a diagnostic biomarker in diabetic kidney disease and idiopathic pulmonary fibrosis, where it's associated with ketone body metabolism abnormalities 45. The enzyme also responds to cellular stress conditions, including extracellular acidic pH environments 6.