ECI2 (enoyl-CoA delta isomerase 2) is a mitochondrial and peroxisomal enzyme that catalyzes the isomerization of 3-cis and 3-trans double bonds to 2-trans form in enoyl-CoA species during fatty acid beta-oxidation, with preference for 3-trans substrates 1. The enzyme plays a crucial role in lipid metabolism and cellular energy production. ECI2 functions as a tumor suppressor in multiple cancers, including colorectal cancer where it reduces ether lipid-mediated IL-8 expression and neutrophil extracellular trap formation by inhibiting peroxisomal localization of AGPS 2. In prostate carcinoma, ECI2 expression correlates with EZH2 levels, though its clinical significance remains unclear 3. ECI2 demonstrates tissue-specific tumor suppressive effects in clear cell renal cell carcinoma, where overexpression inhibits proliferation and migration while increasing chemotherapy sensitivity 4. The gene shows altered expression in various cardiac conditions, including diabetic cardiomyopathy where it contributes to fatty acid metabolism disorders 5, and acute myocardial infarction where it exhibits dynamic expression patterns in cardiomyocytes and other cardiac cell types 6. ECI2 also serves as a prognostic marker in glioma, particularly in oligodendrocytes 7.