Mitochondrial D-loop methylation levels inversely correlate with disease duration in amyotrophic lateral sclerosis

Abstract

Aim: To correlate mitochondrial D-loop region methylation levels and mtDNA copy number with disease duration in familial amyotrophic lateral sclerosis (ALS) patients. Patients & methods: The study population included 12 ALS patients with a mutation in SOD1 and 13 ALS patients with the C9orf72 hexanucleotide repeat expansion. Methylation levels of the D-loop region and mtDNA copy number were quantified using pyrosequencing and quantitative PCR, respectively. Results: We observed that D-loop methylation levels inversely correlated while mtDNA copy number positively correlated with disease duration. Conclusion: Considering the central role played by mitochondria in ALS, this preliminary study provides new knowledge for future studies aimed at identifying biomarkers of disease progression and new targets for therapeutic interventions. Plain language summary: Amyotrophic lateral sclerosis is a devastating neurodegenerative disease which leads to the patient’s death a few years after the onset of the first symptoms. There are currently no treatments to cure the disease, and the only drugs available are able to prolong patients’ lives by only a few months. Patients may have much variability in the presentation of symptoms, including different duration of disease. This study aims to research whether mitochondrial DNA methylation, a mechanism involved in the biology of the mitochondrion, is associated with the duration of the disease. We observed that methylation of mitochondrial DNA inversely correlates with the disease duration, providing new knowledge for future studies aimed at identifying biomarkers of disease progression. Tweetable abstract: Peripheral blood mitochondrial DNA methylation inversely correlates with disease duration in amyotrophic lateral sclerosis patients.