Exploring the Causal Effect of Mitochondrial DNA Copy Number on Obstructive Sleep Apnea

Area of Science:

• Genetics
• Sleep Medicine
• Mitochondrial Biology

Background:

• Obstructive sleep apnea (OSA) is a common sleep disorder.
• Mitochondrial DNA (mtDNA) copy number has been associated with OSA, but causality is unclear.

Purpose of the Study:

• To investigate the causal relationship between mitochondrial DNA (mtDNA) copy number and obstructive sleep apnea (OSA).
• To explore the potential mediating role of immune cells in the relationship between mtDNA copy number and OSA.

Main Methods:

• Two-sample Mendelian randomization (MR) analysis using genome-wide association study data.
• Inverse variance weighted (IVW) method for causal effect estimation.
• Sensitivity analyses including MR-Egger intercept and Cochran's Q test.
• Mediator MR analysis to assess immune cell mediation.

Main Results:

• A significant negative causal effect of mtDNA copy number on OSA was observed (OR = 0.844, p = 0.03).
• OSA did not show a causal effect on mtDNA copy number (OR = 0.995, p = 0.791).
• No significant mediating effect of CD4-CD8 T cell count was found between mtDNA copy number and OSA.

Conclusions:

• Reduced mtDNA copy number is a risk factor for developing OSA.
• OSA is not a cause of altered mtDNA copy number.
• Interventions targeting mitochondrial dysfunction may offer a strategy for OSA prevention or treatment.