BBLN (bublin coiled-coil protein) is essential for intermediate filament organization and cell junction integrity, with emerging evidence of cardiovascular pathophysiology. In intestinal cells, BBLN organizes intermediate filaments and regulates lumen morphology through molecular adaptor functions 1. Beyond its canonical role in cytoskeletal organization, BBLN plays a critical pathological role in cardiac disease. BBLN is upregulated in hearts of tetralogy of Fallot (TOF) patients with cyanosis and correlates with cardiac remodeling 2. Mechanistically, BBLN promotes heart failure features, cardiac inflammation, fibrosis, and necroptosis by activating calcium/calmodulin-dependent protein kinase II delta (CAMK2D), with disease severity dependent on protein dosage 2. BBLN expression is induced by hypoxia—a major TOF feature—and chr9 pressure overload, and BBLN downregulation decreases CAMK2D hyperactivity and cardiovascular dysfunction 2. Genetic studies identify BBLN as a Hero-protein with chaperone-like activities; the rs2900262 SNP demonstrates sex-specific effects on coronary artery disease risk, with the T allele conferring increased risk in females and protective effects in males 3. Bioinformatic analysis reveals BBLN's high regulatory potential in cardiovascular disease pathogenesis 4. Thus, BBLN functions as both a structural organizer of intermediate filaments and a pathogenic mediator of cardiac remodeling through CAMK2D signaling.