Systemic Evidence for Mitochondrial Dysfunction in Age-Related Macular Degeneration as Revealed by mtDNA Copy Number...

Area of Science:

• Ophthalmology
• Gerontology
• Mitochondrial Biology

Background:

• Mitochondrial dysfunction and increased reactive oxygen species contribute to aging and age-related macular degeneration (AMD).
• Damage to mitochondrial DNA (mtDNA) leads to dysfunctional mitochondria, potentially harming retinal tissue.
• It remains unclear if these mitochondrial effects are localized to the retina or present systemically.

Purpose of the Study:

• To investigate the association between blood mitochondrial DNA copy number (mtDNA-CN) and age-related macular degeneration (AMD).
• To determine if mtDNA-CN in peripheral blood can serve as a systemic biomarker for AMD.

Main Methods:

• Quantitative PCR (qPCR) with plasmid normalization was used to measure mtDNA copy number (mtDNA-CN) in peripheral blood.
• The study included elderly participants with and without AMD from the AugUR study (n = 2262).
• Participants were categorized into early AMD (n = 453), late AMD (n = 170), and AMD-free (n = 1630) groups.

Main Results:

• Significantly lower mtDNA-CN was observed in the blood of participants with both early and late AMD compared to AMD-free individuals.
• Regression analyses revealed that lower mtDNA-CN was associated with late AMD.
• A reduction of one standard deviation in mtDNA-CN increased the risk for late AMD by 24%, most notably in geographic atrophy (OR = 1.76).

Conclusions:

• Blood mtDNA-CN is significantly lower in individuals with AMD, suggesting a systemic link.
• Blood mtDNA-CN may serve as a more accessible biomarker for AMD than retinal mtDNA-CN.
• This finding offers new insights into the role of systemic mitochondrial health in AMD pathogenesis.