TNNC1 and ventricular fibrillation: Besides TNNC1 variants causing an extremely limited number of total HCM cases, the identification of a specific TNNC1 variant (alanine substituted by serine at position 31, A31S) in a pediatric-onset HCM proband opened novel perspectives in the understanding of HCM pathogenesis, revealing the specific mechanisms underpinning the increased sensitivity of myofibers to Ca2+ and its direct relationship with the increased occurrence of ventricular fibrillation.