TTN and familial dilated cardiomyopathy: We found a similar variant frequency (ratio 0.0017) in an available cohort of DCM patients (n = 580), i.e., only one variant at a predicted splice-donor site (ENST00000355849.10:c.207+1G>T) in one DCM patient; however, we did not find any missense variant in SLM2. The rare occurrence of such mutations might be explained by the severe functional consequence, i.e., a multitude of mRNA targets may be misspliced by a mutated splicing factor; however, mutations in a gene encoding a structural protein such as titin result in a more favorable clinical course of cardiomyopathy.