Hypertrophic cardiomyopathy caused by gene variants coding sarcomeric proteins—β-myosin heavy chain (MYH7) and myosin binding protein C (MYBPC3)—account for up to 50% of all clinical cases: myosin light chain 2 (MYL2), myosin light chain 3 (MYL3), and cardiac troponin T (TNNT2) in 5–10%, cardiac troponin I (TNNI3) in 5%, cardiac troponin C (TNNC1) in < 1%, cardiac α-actin (ACTC1) in < 1%, α-tropomyosin (TPM1) in 1.5%, and cysteine and glycine rich protein 3 (CSRP3) [64]. The gene discussed is TNNI3; the disease is hypertrophic cardiomyopathy.