Mitochondrial DNA Copy Number as a Hidden Player in the Progression of Multiple Sclerosis: A Bidirectional Two-Sample...

Area of Science:

• Neuroimmunology
• Genetics
• Mitochondrial Biology

Background:

• The link between mitochondrial DNA copy number (mtDNA-CN) and multiple sclerosis (MS) progression is not well understood, with prior studies showing conflicting results.
• Mitochondrial dysfunction is increasingly implicated in the pathophysiology of neurodegenerative diseases like MS.

Purpose of the Study:

• To investigate the potential causal relationship between mtDNA-CN and MS progression using a bidirectional Mendelian randomization (MR) approach.
• To clarify whether mtDNA-CN influences MS or if MS progression affects mtDNA-CN.

Main Methods:

• Utilized summary statistics from large genome-wide association studies (GWAS) for mtDNA-CN and MS severity.
• Employed a bidirectional two-sample Mendelian randomization (MR) analysis, primarily using the inverse variance weighted (IVW) method.
• Conducted sensitivity analyses to assess heterogeneity and pleiotropy, ensuring result robustness.

Main Results:

• Forward MR analysis showed no significant association between mtDNA-CN and MS progression (P=0.487).
• Reverse MR analysis revealed a significant causal association where MS progression may influence mtDNA-CN (β=-0.010, P=0.036).
• Analyses indicated no significant heterogeneity or horizontal pleiotropy, and sensitivity analyses supported the findings.

Conclusions:

• MS progression appears to causally impact mtDNA-CN, suggesting a critical role for mitochondria in MS.
• Further investigation is required to validate mtDNA-CN as a reliable biomarker for MS.
• Understanding the underlying molecular mechanisms is essential for developing targeted MS therapies.