TTN and familial dilated cardiomyopathy: This observation was initially confounded by the appearance of TTN truncating variants in normal cohorts (up to 3%) (Roberts et al. 2015), but it is now evident that DCM associated TTN variants tend to cluster predominantly in the A-band portion of Titin, while variants found in controls tend to spare the A-band region and/or are in exons that have low usage in adult cardiac transcripts (Akinrinade et al. 2015a; Roberts et al. 2015; Schafer et al. 2017).