The review analyses the scope of the genes of Mendelian cardiomyopathies (CM), specifically hypertrophic, dilated, arrhythmogenic, and restrictive cardiomyopathy. According to Simple ClinVar, pathogenic/likely pathogenic variants of 75 genes trigger one or more types of CM. At the same time, these genes are characterized by their expression in various tissues and organs (not only in the heart and blood vessels but also in various parts of the brain, gastrointestinal tract, etc.), as well as by their involvement in a variety of metabolic pathways and biological processes. These data are generally consistent with the results of genomewide association studies (GWAS). Polymorphisms of the CM genes are associated with various types of CM and other cardiovascular diseases, as well as obesity, various diseases of the musculoskeletal and nervous systems, and mental, oncological, infectious, and other diseases. In addition to pathological conditions, common variants of the CM genes contributed to the variation of a wide range of quantitative traits, including pathogenetically significant for various multifactorial diseases. The non-randomness of the identified associations of CM genes with a wide range of diseases is evidenced by comorbidity of CM with GWAS-associated diseases or the involvement of the latter as a symptom, a risk factor for the development of myocardial pathology, and a modifier of the clinical presentation; overlapping of the affected organ systems and the spectrum of pathologies associated with common variants (according to GWAS) and to which rare pathogenic variants (according to OMIM) of the CM genes lead; and confirmation of the involvement of CM genes in the pathogenesis of diseases of other organ systems at the molecular level. Thus, the data presented in the review indicate the wide scope of the genes of primary CMs, which goes beyond the cardiovascular system. That indicates the relevance of conducting comprehensive studies aimed at determining the cause-and-effect relationships between the CM.