TMEM170A is a transmembrane protein localized to the endoplasmic reticulum (ER) and nuclear envelope (NE) that functions as a regulator of membrane morphogenesis 1. It acts as an ER-sheet-promoting protein, with overexpression inducing ER sheet formation while downregulation specifically promotes tubular ER formation 1. TMEM170A influences NE expansion and nuclear pore complex (NPC) density, as its downregulation alters nuclear shape, decreases NPC density, and causes mislocalization of inner nuclear membrane proteins 1. Mechanistically, TMEM170A interacts with RTN4 (reticulon family member) in an antagonistic manner to regulate ER and NE organization 1. Disease relevance includes associations with multiple complex traits: TMEM170A variants showed sex-specific genetic associations with chr16 obstructive pulmonary disease (COPD) 2, genetic overlap with migraine and type 2 diabetes 3, and associations with pancreatic cancer risk 4. Additionally, the BCAR1-CFDP1-TMEM170A locus on chromosome 16.1 is associated with carotid intima-media thickness and coronary artery disease risk, with evidence suggesting BCAR1 as the primary causal gene at this locus 56.