We also see this commonly in certain breeds and family lines which suggests a strong genetic component to the disease. (perkinsvetclinic.com)
The fact that canine DCM occurs at a higher incidence in specific breeds suggests a heritable genetic component to this disease, although it is likely that it's etiology is multifactorial. (www2.vet.cornell.edu)
This condition is called autoimmune thyroiditis There is a strong genetic component to this disease. (breedingbusiness.com)