TTN and heart disorder: Missense variants in Fn3-119 (A150) cause hereditary myopathy with early respiratory failure (HMERF) (Pfeffer et al., 2012), a single missense variant (Ala178Asp) in the second domain of titin (Ig-2 / Z2) has been linked to a dominantly-inherited heart disease (Hastings et al., 2016), and multiple missense, truncating and insertion / deletion variants in the final domain of titin (Ig-169 / M10) have been linked to tibial muscular dystrophy (TMD) and limb girdle muscular dystrophy type 2 J (LGMD2J) (Hackman et al., 2002).