Neuropathology of frontotemporal lobar degeneration-tau (FTLD-tau)

Area of Science:

• Neuroscience
• Genetics
• Pathology

Background:

• Frontotemporal lobar degeneration with tau pathology (FTLD-tau) presents significant clinical and pathological heterogeneity.
• Familial forms are frequently linked to mutations in the tau gene (MAPT).
• Tauopathies are classified based on the predominant tau protein isoforms (3R or 4R) involved in microtubule binding.

Purpose of the Study:

• To explore the heterogeneity within FTLD-tau, particularly concerning MAPT mutations.
• To differentiate between subtypes of FTLD-tau, including Pick's disease (PiD), corticobasal degeneration (CBD), and progressive supranuclear palsy (PSP).
• To understand the relationship between tau protein composition, anatomical distribution, and clinical presentation.

Main Methods:

• Review of clinical and pathological features of FTLD-tau subtypes.
• Analysis of tau protein species (3R and 4R) associated with specific MAPT mutations.
• Correlation of neuropathological findings (Pick bodies, globose tangles, coiled bodies, astrocytic plaques) with clinical syndromes.
• Examination of the anatomical distribution of tau pathology.

Main Results:

• FTLD-tau exhibits heterogeneity, with MAPT mutations contributing to varied clinical and pathological presentations.
• Pick's disease is characterized by predominant 3R tau, while CBD and PSP involve 4R tau.
• PSP and CBD show considerable overlap, lacking distinct clinical or biomarker differentiation, with diagnosis relying on postmortem examination.
• The anatomical distribution of tau pathology dictates the clinical phenotype in PiD, PSP, and CBD.

Conclusions:

• FTLD-tau subtypes, including PiD, PSP, and CBD, are defined by distinct tau pathologies and anatomical distributions.
• MAPT mutations can lead to different tau profiles (3R, 4R, or mixed), influencing disease characteristics.
• The precise mechanisms underlying selective cortical vulnerability in FTLD-tau remain undetermined.