Rare diseases (monogenic), such as hypertrophic cardiomyopathy (e.g., MYBPC3, MYH7 mutations), dilated cardiomyopathy (LMNA, RBM20), or inherited arrhythmias (KCNQ1, RYR2), are often caused by single, well-characterized mutations [101]. The gene discussed is RYR2; the disease is hypertrophic cardiomyopathy.