ORMDL3 is an endoplasmic reticulum protein that regulates sphingolipid homeostasis by modulating serine palmitoyltransferase (SPT) activity in response to ceramide levels. When complexed to SPT, ceramide binding to ORMDL3's N-terminus stabilizes a conformation blocking SPT substrate entry, preventing excessive ceramide accumulation while maintaining sufficient levels for complex sphingolipid production [PubMed:37308477]. This mechanism prevents ceramide-induced apoptosis while supporting intracellular sphingolipid balance. ORMDL3 has emerged as a major asthma susceptibility gene, with genome-wide association studies identifying risk alleles on chromosome 17 that increase ORMDL3 expression in lung tissue [PubMed:35353673]. Disease-associated ORMDL3 overexpression drives inflammation-independent asthma pathogenesis through multiple mechanisms: promoting autophagy and epithelial cell death via SERCA2 interaction and impaired intracellular calcium mobilization [PubMed:35353673], increasing airway hyperreactivity through decreased sphingolipid synthesis [PubMed:28030368], upregulating the rhinovirus receptor ICAM1 [PubMed:30339462], and exacerbating cytokine release [PubMed:30339462]. ORMDL3 rs7216389 polymorphism significantly increases asthma susceptibility across multiple populations [PubMed:26125920]. Beyond asthma, ORMDL3 genetic variants associate with inflammatory bowel disease, ankylosing spondylitis, and atherosclerosis [PubMed:29879314], indicating broader roles in inflammatory pathology.