The c.1370T>C (p.Ile457Thr) variant in MYH7 has been identified in >20 individuals with HCM (PS4_Strong; Waldmüller 2011 PMID: 21750094; Fokstuen 2011 PMID: 21239446; Helms 2016: 27688314; Homburger 2016 PMID: 27247418; Murphy 2016 PMID: 26914223; Ingles 2017 PMID: 28408708; Ross 2017 PMID: 28615295; Viswanathan 2017 PMID: 29121657; Walsh 2017 PMID:27532257; Ko 2018 PMID: 28640247; Centenary Institute Sydney pers. comm.; GeneDx pers. comm., Invitae pers. comm.; LMM pers. comm.; OGML pers. comm.). This variant also segregated with HCM in 1 affected relative (GeneDx pers. comm.); however, this data is currently insufficient to establish co-segregation with disease and apply PP1. Additionally, this variant has also been reported in 1 individual with left bundle branch block, 1 individual with sudden cardiac arrest (who carried additional variants in other cardiomyopathy associated genes) and 1 individual with myopathy who also had additional variants in myopathy-associated genes and segregated with myopathy in one affected relative (Ambry pers. comm.; CHEO pers. comm.; Invitae pers. comm.). This variant has also been identified in 0.0009% (1/113764) of European chromosomes by gnomAD v2.1.1 (PM2; http://gnomad.broadinstitute.org). In vitro functional studies provide some evidence that this variant could impact protein function (Adhikari 2019 PMID: 31213605); however, this data is currently insufficient to establish functional impact and apply PS3. This variant lies in the head region of the protein (aa 181-937) and missense variants in this region are statistically more likely to be disease-associated (PM1; Walsh 2017 PMID:27532257). Computational prediction tools and conservation analysis suggest that this variant may impact the protein (PP3). In summary, this variant meets criteria to be classified as likely pathogenic for hypertrophic cardiomyopathy in an autosomal dominant manner. MYH7-specific ACMG/AMP criteria applied (Kelly 2018 PMID:29300372): PS4; PM2; PM1; PP3.