ORMDL1 is an endoplasmic reticulum membrane protein that serves as a critical negative regulator of sphingolipid biosynthesis 1. It functions by modulating serine palmitoyltransferase (SPT) activity in response to ceramide levels; when complexed with SPT, ceramide binding to ORMDL1's N-terminus stabilizes a conformation that blocks SPT substrate entry, preventing excess ceramide accumulation while maintaining sufficient levels for complex sphingolipid synthesis 1. ORMDL1 works redundantly with ORMDL2 and ORMDL3 to regulate sphingolipid homeostasis, though individual isoforms have distinct roles—triple deletion causes dramatic increases in ceramides and downstream sphingolipid species, while single ORMDL3 knockout shows modest effects 2. Dysregulation of ORMDL1 expression correlates with multiple disease states. Elevated ORMDL1 expression serves as a poor prognostic marker in esophageal squamous cell carcinoma and diffuse large B cell lymphoma, correlating with unfavorable survival outcomes and immune cell infiltration patterns 34. In metabolic disease, ORMDL dysregulation is implicated in obesity pathogenesis through altered sphingolipid metabolism 5. ORMDL1 has also been identified as a component of pyroptosis-related prognostic signatures in bladder cancer 6. Clinical significance includes potential utility as a molecular biomarker for cancer diagnosis and prognosis, with emerging therapeutic targeting possibilities in multiple malignancies.