Identifying modifier genes for hypertrophic cardiomyopathy

•Modifier genes regulate clinical phenotypes of hypertrophic cardiomyopathy (HCM).•A large murine genetic reference population detects modifier genes for HCM.•Quantitative Trait Locus mapping is conducted with WebQTL in GeneNetwork.•Quantitative trait loci related to myocyte size are located on chromosomes 2 and 5.•Xirp2 and Nos3 serve as candidate modifier genes for cardiac hypertrophy in HCM.