Causal Relationship Between Mitochondrial DNA Copy Number and Intervertebral Disc Degeneration: A Bidirectional...

Area of Science:

• Genetics
• Biochemistry
• Orthopedics

Background:

• Mitochondrial DNA copy number (mtDNA-CN) is implicated in various cellular processes.
• Intervertebral disc degeneration (IVDD) is a common cause of low back pain.
• The potential causal link between mtDNA-CN and IVDD is not well-established.

Purpose of the Study:

• To investigate the potential causal relationship between mtDNA-CN and IVDD.
• To utilize Mendelian randomization (MR) analyses for robust causal inference.
• To explore the bidirectional relationship between mtDNA-CN and IVDD.

Main Methods:

• Bidirectional 2-sample Mendelian randomization (MR) analysis.
• Inverse-variance weighted (IVW) method as the primary analysis.
• Sensitivity analyses including heterogeneity and pleiotropy assessments, and leave-one-out analysis.

Main Results:

• No significant causal association was found between genetically predicted mtDNA-CN and IVDD risk (OR = 0.91, P = 0.1731).
• Reverse MR analysis also showed no significant causal effect of IVDD on mtDNA-CN.
• Sensitivity analyses confirmed the robustness of the findings, with no evidence of horizontal pleiotropy.

Conclusions:

• This study provides no evidence for a causal relationship between mtDNA-CN and IVDD in either direction.
• The findings suggest that genetic factors influencing mtDNA-CN do not play a direct causal role in the development of IVDD.
• Further research is warranted to elucidate the complex interplay of genetic and environmental factors in IVDD pathogenesis.