These TTNtv have been associated with 25% of familial cases of DCM, and 10–20% of sporadic cases.2–7 Only variants located in exons that are highly likely to be spliced into adult cardiac TTN transcripts, known as high percentage spliced in (hiPSI) variants, are pathogenic.3 hiPSI TTNtvs may cause DCM by reducing abundance of full-length TTN protein (haploinsufficiency) and/or through dominant negative effects.8,9. Here, TTN is linked to familial dilated cardiomyopathy.