Circulating Non-Coding RNA Levels Are Altered in Autosomal Dominant Frontotemporal Dementia

Area of Science:

• Neuroscience
• Genetics
• Molecular Biology

Background:

• Frontotemporal Dementia (FTD) is a highly heritable neurodegenerative disorder.
• Genetic factors, including mutations in MAPT, GRN, and C9ORF72, are major contributors to FTD heritability.
• Pathological hallmarks of FTD include tau or TAR DNA-binding protein (TDP-43) aggregates, with emerging evidence implicating non-coding RNAs (ncRNAs) in disease mechanisms.

Purpose of the Study:

• To investigate the differential expression of ncRNAs in genetic forms of FTD.
• To explore the potential of ncRNA profiles as biomarkers distinguishing FTD subtypes.
• To understand the role of ncRNAs in the distinct pathological pathways of FTD.

Main Methods:

• An exploratory analysis was conducted using specific arrays to assess the expression levels of 84 microRNAs (miRNAs) and 84 long non-coding RNAs (lncRNAs).
• The study population included 24 genetic FTD patients (8 each with GRN, C9ORF72, and MAPT mutations), 8 sporadic FTD patients, and 8 healthy controls.
• Differential expression analysis was performed to compare ncRNA levels between patient groups and controls.

Main Results:

• A generalized downregulation of ncRNAs was observed in patients with GRN and C9ORF72 mutations compared to controls, with significant findings for several miRNAs including miR-155-5p and miR-15a-5p.
• MAPT mutation carriers exhibited a robust upregulation of several ncRNAs, notably miR-222-3p, miR-15a-5p, and miR-27a-3p.
• Distinct ncRNA dysregulation patterns were identified, suggesting a link between specific ncRNA profiles and the underlying TDP-43 or tau pathologies.

Conclusions:

• The study reveals distinct ncRNA expression patterns associated with different genetic mutations in FTD.
• These findings suggest that ncRNAs may serve as distinguishing biomarkers for FTD subtypes.
• Further validation in larger cohorts is necessary to confirm these preliminary results and their clinical implications.