Troponin I, fast skeletal muscle (TNNI2), belongs to the troponin I gene family, and a part of the troponin complex including troponin T, troponin C and troponin I subunits. The troponin complex, along with tropomyosin, is responsible for the calcium-dependent regulation of striated muscle contraction. TNNI2 is also suppresses tumor growth in human ovarian carcinoma. Mutations in TNNI2 cause myopathy and distal arthrogryposis type 2B.