STX18 (syntaxin 18) is an endoplasmic reticulum-resident t-SNARE protein that functions primarily in vesicular trafficking between the ER and Golgi apparatus 1. It mediates retrograde transport of Golgi-derived vesicles back to the ER and plays a crucial role in collagen II transport during chondrogenesis 1. Beyond classical membrane trafficking, STX18 acts as a negative regulator of lipophagy by binding to ATG14 and inhibiting lipid droplet degradation through autophagy 23. This lipophagy regulation has significant disease implications: lipid accumulation dysregulation is linked to age-related macular degeneration, nonalcoholic fatty liver disease, and neurodegenerative diseases including Alzheimer's and Parkinson's disease 2. STX18 deficiency impairs antero- and retrograde vesicular transport, causing severe osteochondrodysplasia in humans and cartilage/bone developmental defects in zebrafish 1. Clinically, STX18 variants are associated with congenital heart disease, particularly atrial septal defect and ventricular septal defect in multiple populations 45. Additionally, STX18 is overexpressed in breast cancer and suppresses cancer cell growth, suggesting potential tumor-suppressive functions 6. A related lncRNA, STX18-AS1, regulates cardiomyocyte differentiation during cardiac development 7.