Myasthenic Syndrome, Congenital, 20, Presynaptic, also known as congenital myasthenic syndrome 20, is related to familial isolated restrictive cardiomyopathy and systolic heart failure. An important gene associated with Myasthenic Syndrome, Congenital, 20, Presynaptic is SLC5A7 (Solute Carrier Family 5 Member 7), and among its related pathways/superpathways are Cardiac conduction and Cardiac progenitor differentiation. Affiliated tissues include skeletal muscle, and related phenotypes are ptosis and facial palsy