MYOM1 (myomesin 1) is a major structural component of the vertebrate myofibrillar M band that binds myosin, titin, and light meromyosin in a dose-dependent manner 1. It plays critical roles in sarcomere assembly, contractility regulation, and cardiomyocyte development 2. MYOM1 demonstrates mosaic patterns of expression across cardiomyocytes, with differential atrial and ventricular expression patterns 3. Loss-of-function MYOM1 variants are associated with dilated cardiomyopathy (DCM) and heart failure 1. The pathogenic mechanism involves disruption of sarcoplasmic reticulum calcium homeostasis through downregulation of key regulators including RYR2 and SERCA2, leading to impaired calcium transients and sarcomeric disorganization 1. MYOM1 knockout in human cardiomyocytes recapitulates myocardial atrophy via calcium homeostasis impairment 2. Beyond cardiac disease, MYOM1 is consistently downregulated across multiple cancer types and associates with poor clinical outcomes 4. In sepsis models, MYOM1 is under-expressed and targeted by miR-135a, with MYOM1 restoration providing protective effects against LPS-induced cellular injury 5. MYOM1 variants have been identified in fetal cardiomyopathy cases 6, establishing MYOM1 as a disease-relevant determinant of myocardial remodeling and excitation-contraction coupling with potential therapeutic applications 1.