The prevalence of DCM is around 1:2500 in the vestern world and multiple screening studies of first generation relatives to DCM patients have shown that in 30-50% of the cases it was possible to identify at least one other relative with the same disease. The inheritance is often dominant and at this point there has been reported disease associated mutations in over 40 different genes. The clinical examinations of affected families have shown that the expression of the disease varies from very critical symptoms and changes in the heart to discrete changes of the heart with no accompanying symptoms. Furthermore the time of debut of DCM can vary a lot even within the same family and the disease can manifest itself from early childhood to late adulthood.