A 65-year-old man with Parkinson disease has substantia nigra degeneration. The pathological hallmark inclusions are composed predominantly of:

• A Hyperphosphorylated tau protein (paired helical filaments)
• B Alpha-synuclein protein (Lewy bodies and Lewy neurites) ✓
• C Huntingtin protein with polyglutamine expansion
• D TDP-43 (transactive response DNA binding protein 43)

Explanation

Parkinson disease (PD) belongs to the synucleinopathies. The pathological hallmarks are Lewy bodies (concentric eosinophilic intracytoplasmic inclusions) and Lewy neurites in dopaminergic neurons of the substantia nigra pars compacta. Lewy bodies are composed predominantly of misfolded, aggregated alpha-synuclein (encoded by SNCA), ubiquitin, and neurofilaments. Braak staging describes rostrocaudal spread of alpha-synuclein pathology. Hyperphosphorylated tau (neurofibrillary tangles) characterizes Alzheimer disease and other tauopathies; huntingtin with polyQ expansion is in Huntington disease; TDP-43 inclusions characterize ALS and FTLD-TDP.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.