Mitochondrial DNA in idiopathic cardiomyopathy.

Aims: To investigate the frequency of pathogenic mitochondrial DNA mutations in idiopathic cardiomyopathy.

Methods And Results: We investigated the occurrence of seven previously reported pathogenic mitochondrial DNA point mutations in 52 patients with idiopathic dilated cardiomyopathy (blood n=33, myocardium n=19), 10 patients with hypertrophic cardiomyopathy (blood n=7, myocardium n=3), 67 controls with ischaemic heart disease (blood n=53, myocardium n=14) and eight controls with no overt cardiac disease (blood n=4, myocardium n=4). Total DNA or cell lysates were studied by polymerase chain reaction amplification and restriction fragment length polymorphism analysis for the identification of the following mitochondrial DNA point mutations: A3243G, A3252G, A3260G, A4269G, A8344G, T8993G/C and T9997C. None of these point mutations were detected in the blood or myocardium of any of the individuals with dilated or hypertrophic cardiomyopathy or in the controls. In addition we investigated the occurrence of major deletions of mitochondrial DNA in eight patients with dilated cardiomyopathy (myocardium n=7, skeletal muscle n=1), three patients with ischaemic heart disease (myocardium n=3) and one control myocardium by Southern blot analysis. Deletions were not detected in any of the patients.

Conclusion: The results suggest that although these mutations are known to be associated with specific cardiomyopathies, they are not a common feature of idiopathic cardiomyopathy.