Placing these current findings in context with our evidence demonstrating (a) increased (>3-fold) binding of mutant sMyBP-C to myosin (11) and (b) the unique role of sMyBP-C in thick filament assembly and stabilization (16), we posit that this MYBPC1 myopathy originates from alterations in the structure and, consequently, the regulation of myofilaments. The gene discussed is MYBPC1; the disease is myopathy.