@article {7548, title = {Association of Mitochondrial DNA Copy Number With Cardiovascular Disease.}, journal = {JAMA Cardiol}, volume = {2}, year = {2017}, month = {2017 Nov 01}, pages = {1247-1255}, abstract = {

Importance: Mitochondrial dysfunction is a core component of the aging process and may play a key role in atherosclerotic cardiovascular disease. Mitochondrial DNA copy number (mtDNA-CN), which represents the number of mitochondria per cell and number of mitochondrial genomes per mitochondrion, is an indirect biomarker of mitochondrial function.

Objective: To determine whether mtDNA-CN, measured in an easily accessible tissue (buffy coat/circulating leukocytes), can improve risk classification for cardiovascular disease (CVD) and help guide initiation of statin therapy for primary prevention of CVD.

Design, Setting, and Participants: Prospective, population-based cohort analysis including 21 870 participants (20 163 free from CVD at baseline) from 3 studies: Cardiovascular Health Study (CHS), Atherosclerosis Risk in Communities Study (ARIC), and Multiethnic Study of Atherosclerosis (MESA). The mean follow-up was 13.5 years. The study included 11 153 participants from ARIC, 4830 from CHS, and 5887 from MESA. Analysis of the data was conducted from March 10, 2014, to January 29, 2017.

Exposures: Mitochondrial DNA-CN measured from buffy coat/circulating leukocytes.

Main Outcomes and Measures: Incident CVD, which combines coronary heart disease, defined as the first incident myocardial infarction or death owing to coronary heart disease, and stroke, defined as the first nonfatal stroke or death owing to stroke.

Results: Of the 21 870 participants, the mean age was 62.4 years (ARIC, 57.9 years; MESA, 62.4 years; and CHS, 72.5 years), and 54.7\% of participants were women. The hazard ratios for incident coronary heart disease, stroke, and CVD associated with a 1-SD decrease in mtDNA-CN were 1.29 (95\% CI, 1.24-1.33), 1.11 (95\% CI, 1.06-1.16), and 1.23 (95\% CI, 1.19-1.26). The associations persisted after adjustment for traditional CVD risk factors. Addition of mtDNA-CN to the 2013 American College of Cardiology/American Heart Association Pooled Cohorts Equations for estimating 10-year hard atherosclerosis CVD risk was associated with improved risk classification (continuous net reclassification index, 0.194; 95\% CI, 0.130-0.258; P < .001). Mitochondrial DNA-CN further improved sensitivity and specificity for the 2013 American College of Cardiology/American Heart Association recommendations on initiating statin therapy for primary prevention of ASCVD (net 221 individuals appropriately downclassified and net 15 individuals appropriately upclassified).

Conclusions and Relevance: Mitochondrial DNA-CN was independently associated with incident CVD in 3 large prospective studies and may have potential clinical utility in improving CVD risk classification.

}, issn = {2380-6591}, doi = {10.1001/jamacardio.2017.3683}, author = {Ashar, Foram N and Zhang, Yiyi and Longchamps, Ryan J and Lane, John and Moes, Anna and Grove, Megan L and Mychaleckyj, Josyf C and Taylor, Kent D and Coresh, Josef and Rotter, Jerome I and Boerwinkle, Eric and Pankratz, Nathan and Guallar, Eliseo and Arking, Dan E} } @article {8480, title = {Mitochondrial DNA copy number can influence mortality and cardiovascular disease via methylation of nuclear DNA CpGs.}, journal = {Genome Med}, volume = {12}, year = {2020}, month = {2020 Sep 28}, pages = {84}, abstract = {

BACKGROUND: Mitochondrial DNA copy number (mtDNA-CN) has been associated with a variety of aging-related diseases, including all-cause mortality. However, the mechanism by which mtDNA-CN influences disease is not currently understood. One such mechanism may be through regulation of nuclear gene expression via the modification of nuclear DNA (nDNA) methylation.

METHODS: To investigate this hypothesis, we assessed the relationship between mtDNA-CN and nDNA methylation in 2507 African American (AA) and European American (EA) participants from the Atherosclerosis Risk in Communities (ARIC) study. To validate our findings, we assayed an additional 2528 participants from the Cardiovascular Health Study (CHS) (N = 533) and Framingham Heart Study (FHS) (N = 1995). We further assessed the effect of experimental modification of mtDNA-CN through knockout of TFAM, a regulator of mtDNA replication, via CRISPR-Cas9.

RESULTS: Thirty-four independent CpGs were associated with mtDNA-CN at genome-wide significance (P < 5 {\texttimes} 10). Meta-analysis across all cohorts identified six mtDNA-CN-associated CpGs at genome-wide significance (P < 5 {\texttimes} 10). Additionally, over half of these CpGs were associated with phenotypes known to be associated with mtDNA-CN, including coronary heart disease, cardiovascular disease, and mortality. Experimental modification of mtDNA-CN demonstrated that modulation of mtDNA-CN results in changes in nDNA methylation and gene expression of specific CpGs and nearby transcripts. Strikingly, the "neuroactive ligand receptor interaction" KEGG pathway was found to be highly overrepresented in the ARIC cohort (P = 5.24 {\texttimes} 10), as well as the TFAM knockout methylation (P =~4.41 {\texttimes} 10) and expression (P =~4.30 {\texttimes} 10) studies.

CONCLUSIONS: These results demonstrate that changes in mtDNA-CN influence nDNA methylation at specific loci and result in differential expression of specific genes that may impact human health and disease via altered cell signaling.

}, issn = {1756-994X}, doi = {10.1186/s13073-020-00778-7}, author = {Castellani, Christina A and Longchamps, Ryan J and Sumpter, Jason A and Newcomb, Charles E and Lane, John A and Grove, Megan L and Bressler, Jan and Brody, Jennifer A and Floyd, James S and Bartz, Traci M and Taylor, Kent D and Wang, Penglong and Tin, Adrienne and Coresh, Josef and Pankow, James S and Fornage, Myriam and Guallar, Eliseo and O{\textquoteright}Rourke, Brian and Pankratz, Nathan and Liu, Chunyu and Levy, Daniel and Sotoodehnia, Nona and Boerwinkle, Eric and Arking, Dan E} } @article {8997, title = {Association of mitochondrial DNA copy number with cardiometabolic diseases.}, journal = {Cell Genom}, volume = {1}, year = {2021}, month = {2021 Oct 13}, abstract = {

Mitochondrial DNA (mtDNA) is present in multiple copies in human cells. We evaluated cross-sectional associations of whole blood mtDNA copy number (CN) with several cardiometabolic disease traits in 408,361 participants of multiple ancestries in TOPMed and UK Biobank. Age showed a threshold association with mtDNA CN: among younger participants (<65 years of age), each additional 10 years of age was associated with 0.03 standard deviation (s.d.) higher level of mtDNA CN ( = 0.0014) versus a 0.14 s.d. lower level of mtDNA CN ( = 1.82 {\texttimes} 10) among older participants (>=65 years). At lower mtDNA CN levels, we found age-independent associations with increased odds of obesity ( = 5.6 {\texttimes} 10), hypertension ( = 2.8 {\texttimes} 10), diabetes ( = 3.6 {\texttimes} 10), and hyperlipidemia ( = 6.3 {\texttimes} 10). The observed decline in mtDNA CN after 65 years of age may be a key to understanding age-related diseases.

}, issn = {2666-979X}, doi = {10.1016/j.xgen.2021.100006}, author = {Liu, Xue and Longchamps, Ryan J and Wiggins, Kerri L and Raffield, Laura M and Bielak, Lawrence F and Zhao, Wei and Pitsillides, Achilleas and Blackwell, Thomas W and Yao, Jie and Guo, Xiuqing and Kurniansyah, Nuzulul and Thyagarajan, Bharat and Pankratz, Nathan and Rich, Stephen S and Taylor, Kent D and Peyser, Patricia A and Heckbert, Susan R and Seshadri, Sudha and Cupples, L Adrienne and Boerwinkle, Eric and Grove, Megan L and Larson, Nicholas B and Smith, Jennifer A and Vasan, Ramachandran S and Sofer, Tamar and Fitzpatrick, Annette L and Fornage, Myriam and Ding, Jun and Correa, Adolfo and Abecasis, Goncalo and Psaty, Bruce M and Wilson, James G and Levy, Daniel and Rotter, Jerome I and Bis, Joshua C and Satizabal, Claudia L and Arking, Dan E and Liu, Chunyu} }