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Updated: Jun 14, 2026
Determination of Mitochondrial Respiration and Glycolysis in Ex Vivo Retinal Tissue Samples
Published on: August 4, 2021
Characterization of retinal and blood mitochondrial DNA from age-related macular degeneration patients
M Cristina Kenney1, Shari R Atilano, David Boyer
1Department of Ophthalmology, University of California, Irvine, Irvine, California, USA. mkenney@uci.edu
Purpose:
To determine mitochondrial (mt)DNA variants in AMD and age-matched normal retinas.
Methods:
Total DNA was isolated from retinas (AMD, n = 13; age-matched normal, n = 13), choroid (AMD, n = 3), and blood (AMD, n = 138; normal, n = 133). Long-extension-polymerase chain reaction amplified the full-length ( approximately 16.2 kb) mtDNA genome. Retinal mtDNA was sequenced for nucleotide variants and length heteroplasmy. Pyrosequencing was performed on heteroplasmic mtDNA. PCR amplification and enzyme digestions were used to analyze for nucleotide changes.
Results:
Retinal mtDNA had a greater number of rearrangements and deletions than did blood mtDNA in normal samples (9.3 +/- 1.78 vs. 3 +/- 1.18, P = 0.019), and AMD samples (14.33 +/- 1.96 vs. 5.2 +/- 0.80, P = 0.0031. Five (55%) of 9 AMD patients had unreported SNPs, and 2 (16.6%) of 12 of the normal group did. The mtDNA coding region had 20 SNPs that produced amino acid changes. The noncoding MT-Dloop region had nucleotide heteroplasmy and length heteroplasmy. There were more SNPs per person in the AMD population than in the older (P = 0.003) and younger (P = 0.05) normal subjects. The C12557T (T-I) in the MT-ND5 gene was present in two AMD subjects (2/138) but was absent in the normal (0/133). Common mutations for Leber's hereditary optic neuropathy (LHON: G11778A; T14484C; and G3460A) were not present in AMD samples.
Conclusions:
AMD subjects have high levels of large mtDNA deletions/rearrangements in the retinas, unreported and amino acid-changing SNPs in the coding genome, and a greater number of SNPs per person in the noncoding MT-Dloop region. These mtDNA variants could diminish energy production efficiency, alter the mtDNA copy numbers and/or impact transcription in AMD retinas.
Insights
Age-related macular degeneration (AMD) retinas exhibit increased mitochondrial DNA (mtDNA) deletions and single nucleotide polymorphisms (SNPs). These genetic variations may impair retinal energy production in AMD patients.
Area of Science:
- Genetics
- Ophthalmology
- Mitochondrial Biology
Background:
- Age-related macular degeneration (AMD) is a leading cause of vision loss.
- Mitochondrial dysfunction is implicated in various age-related diseases, including AMD.
- Mitochondrial DNA (mtDNA) harbors critical genes for cellular energy production.
Purpose of the Study:
- To investigate and compare mitochondrial DNA (mtDNA) variants in retinas affected by AMD versus age-matched normal retinas.
- To identify specific types and frequencies of mtDNA alterations in AMD.
Main Methods:
- DNA isolation from retinal, choroidal, and blood samples of AMD and control subjects.
- Full-length mtDNA genome amplification using long-extension-polymerase chain reaction.
- Sequencing of retinal mtDNA for nucleotide variants and heteroplasmy.
- Pyrosequencing and PCR-based enzyme digestion for variant analysis.
Main Results:
- Retinal mtDNA showed significantly higher numbers of rearrangements and deletions in AMD compared to normal samples.
- AMD retinas had a higher prevalence of unreported single nucleotide polymorphisms (SNPs), with some altering amino acid sequences.
- AMD patients exhibited more SNPs per person in the noncoding MT-Dloop region compared to normal subjects.
Conclusions:
- AMD retinas are characterized by substantial levels of large mtDNA deletions/rearrangements and numerous coding and noncoding SNPs.
- These identified mtDNA variants in AMD may compromise retinal energy production efficiency and alter mtDNA homeostasis.
- The findings suggest a potential role for mtDNA alterations in the pathogenesis of AMD.
