Copy Number of the Mitochondrial DNA of Leucocytes as an Aging Marker and Risk Factors for the Development of Age-Related Diseases in Humans

Abstract

The mitochondrial DNA (mtDNA) copy number was analyzed via quantitative real-time PCR. A random subset of 996 people was studied (437 men with an average age of 67.3 ± 7.2 years and 559 women with an average age of 67.6 ± 7.1 years). They were selected from a population cohort of 9360 people who were initially examined in the international HAPIEE project (2003–2005, initial age of 45–69 years) in Novosibirsk. The participants were reexamined after 12 years in 2015–2017. The average relative mtDNA copy number in women was significantly higher than in men, regardless of age and smoking status, p = 0.001. The relative mtDNA copy number of blood leukocytes negatively correlated with age in men (p = 0.005) and women (p < 0.001). In the age-standardized analysis, the mtDNA copy number was negatively associated with waist and hip size and heart rate in people of both genders. Associations with some other indicators depend on gender. In women, the mtDNA copy number was negatively associated with the atherogenicity level, body mass indices, and blood glucose level and positively associated with HDL cholesterol. In men, the mtDNA copy number is positively related to the level of physical activity. Regardless of age, the average relative mtDNA copy number in peripheral blood leukocytes was higher in nonsmoking men than in smokers (p = 0.003). The mtDNA copy number was lower in women with diabetes mellitus than in women without it (p = 0.005). In both genders, people with an initial history of arterial hypertension had a lower mtDNA copy number in peripheral blood leukocytes after 12 years of observation than normotonics (p = 0.05). These results broadly support the hypothesis that the mtDNA copy number may act as a biomarker of age.