Fig. 2

Associations between mtDNAcn and D-loop methylation levels. A In the total population, mtDNAcn is negatively correlated with D-loop methylation (r =  − 5.154, P < 0.001). B In the male population, mtDNAcn is negatively correlated with D-loop methylation (r =  − 4.184, P = 0.004). C In the female population, mtDNAcn is negatively correlated with D-loop methylation (r =  − 7.726, P < 0.001). All tests were performed by Pearson correlation analysis