Mitochondrial DNA Content Is Linked to Cardiovascular Disease Patient Phenotypes

BACKGROUND: We sought to determine whether mitochondrial DNA (mtDNA) content can be used as markers for 12 key phenotypes among cardiovascular disease patients, and whether these markers are valid across patients with diverse ancestries. METHODS AND RESULTS: DNA was collected from the peripheral blood of 996 cardiovascular disease patients at the Cleveland Clinic. The mtDNA copy number and DNA‐level variation were assessed from whole‐genome sequence. Patients were also ascertained retrospectively for histories of 10 clinical events, as well as for maximum stenosis and extent of disease at baseline. Self‐reported race and maternal ancestry inferred from mtDNA sequence were recorded. MtDNA copy number and overall mtDNA rare variant load were significantly lower in patients with histories of various adverse clinical events, and mtDNA copy number was inversely correlated with extent of disease. Strong associations were also found between absence of rare variants in the genes MT ‐ATP6 and MT‐COII and patient histories of hyperlipidemia and myocardial infarction, respectively. Importantly, associations were not ancestry dependent. CONCLUSIONS: This study provides evidence that mtDNA copy number in circulation is associated with a variety of cardiovascular disease patient phenotypes. Results also suggest a protective role for some rare inherited mtDNA variants. Overall, the study supports the potential of mtDNA content and abundance as biomarkers in heart disease, in a manner that is valid across diverse ancestries.