TNNT2 and Left ventricular dilatation: In addition to the proband (Fig. 2b and d), the two siblings also carrying the R205Q TNNT2 mutation (one male, one female) showed evidence of marked left ventricular dilation (left ventricular internal diameter in diastole (LVIDd) of 4.4 – 6.6 cm) and reduced ejection fraction (13 – 47 %) (Table 1).