TNNI3 and hypertrophic cardiomyopathy: Further analysis, of the genes affected within the hypertrophic cardiomyopathy ontology (Fig. 7), identified many structural genes including troponin I (Tnni3), troponin T (Tnnt2), troponin C (Tnnc1), α-actin C1 (Actc1) that are important for proper cardiac function (Table 4).