SERPINA11 is a serine protease inhibitor belonging to the serpin family that functions as a serine-type endopeptidase inhibitor [GO:0005615]. Primary evidence indicates SERPINA11 plays a critical role in extracellular matrix (ECM) homeostasis through inhibition of serine proteases involved in ECM remodeling 1. Loss-of-function variants in SERPINA11 cause a perinatal lethal serpinopathy characterized by gross and histopathological ECM disruption, with pronounced protein expression in bronchiolar epithelium 1. Mechanistically, SERPINA11 appears to regulate protease activity essential for proper embryonic development. The gene shows differential expression across multiple tissues, and pathogenic variants result in reduced protein abundance and impaired serine protease inhibition 1. Clinically, SERPINA11 emerges as a biomarker across multiple disease contexts. It represents a novel exosomal biomarker for early atherosclerosis detection 2, predicts blood pressure response to bariatric surgery in adolescents 3, and associates with multidrug therapy response in leprosy with higher baseline expression in poor responders 4. Additionally, SERPINA11 variants are implicated in anterior cruciate ligament injuries through effects on fibroblast deformability and ECM balance 5, and serve as potential diagnostic markers in radiation-related breast cancer 6. These findings establish SERPINA11 as a multifunctional protease inhibitor critical for developmental and systemic homeostasis.