Hypertrophic cardiomyopathy (HCM) is a common genetic disease,predominantly caused by mutations in cardiac sarcomere genes;however,whether MYH7B causes HCM is not known.In this study,549 unrelated patients with HCM and 500 healthycontrols were screened using targeted sequencing and whole exome sequencing together.We observed seven variants in MYH7B causing HCM in 8/549 patients,which accounted for 1.46％ of HCM cases.Of these seven variants,three likely pathogenic variants in MYH7B co-segregating with 5 HCM patients were identified in three HCM pedigrees without other HCM-associated variants.Myh7b knockout rats were generated and cardiac functions were detected by Millar pressure-volume catheterization and echocardiography.Spontaneous HCM phenotypes,cellular disarray and cardiac fibrosis were observed in both Myh7b+/-/Myh7b-/-rats.Transcriptome sequencing showed that calcium is the key mediator of cardiac hypertrophy in Myh7b knockout.Subsequent analysis confirmed over-activation of CaMK-signaling pathway in cardiomyocytes of Myh7b-/-rats.Furthermore,MYH7B expression in human and rat hearts was identified and microRNA-208a and microRNA-499 levels are unchanged in HCM patients and Myh7b+/-/Myh7b-/-rats.This study is the first to identifyMYH7B variants as cause of HCM,which account for 1.46％ of pathogenesisin HCM patients.Activation of CaMK-signaling pathway may be involved in its pathophysiology.