TNNT2 (CTNT, cardiac-specific troponin T) is the tropomyosin-binding subunit of the troponin complex, found on the thin filament of striated muscles. This complex regulates muscle contraction in response to altered calcium ion concentrations. Mutations in TNNT2 are associated with familial hypertrophic cardiomyopathy and with dilated cardiomyopathy. TNNT2 is used as a marker for acute myocarcial infarction and heart injury, as large amounts of the protein are released into the bloodstream when heart muscle is damaged. TNNT2 may also be useful in cancer diagnosis, as amplification of the gene has been found in breast cancer and neuroendocrine prostate cancer. In immunohistochemistry of normal tissue, TNNT2 has cytoplasmic positivity in cardiac myocytes. References: Clin Card. 24 (5): 397–402, PMID: 11346248; Cardiovascular Journal of Africa. 18 (3): 146–53, PMID: 17612745; J Clin Pathol. 2004 Oct; 57(10): 1025–1026, PMID: 15452153; Cancer Discov. 2012 May; 2(5):401-4, PMID: 22588877