Gene TNNC1
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Also known as
Troponin C1, Cardiac/Slow Skeletal, TN-C, CMD13, CMH13Overview
TNNC1 (Troponin C1) encodes the calcium-binding component of the troponin complex in cardiac and slow-twitch skeletal muscle. Troponin C is the calcium sensor of the sarcomere, undergoing conformational changes upon calcium binding that initiate muscle contraction. The protein contains four EF-hand calcium-binding motifs, though only two are functional in cardiac troponin C. When calcium binds during systole, troponin C interacts with troponin I, relieving its inhibition of actin-myosin interaction and allowing muscle contraction to proceed. This calcium-dependent regulation is fundamental to excitation-contraction coupling in the heart.Mutations in TNNC1 are rare causes of both hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM), inherited in an autosomal dominant pattern. These mutations typically alter calcium sensitivity of the myofilaments, either increasing it (often associated with HCM) or decreasing it (associated with DCM). Affected individuals may present with heart failure, arrhythmias, or sudden cardiac death. The variable penetrance and expressivity of TNNC1 mutations make genetic counseling complex. Understanding individual TNNC1 genetics is important for carrier screening, early detection of cardiomyopathy in at-risk family members, and potential future targeted therapies aimed at modulating myofilament calcium sensitivity.