A reassessment of the Lewy body.

Lewy body has been linked to Parkinson's disease for almost a century, but its significance in neurodegenerative diseases is not known. Whether it is toxic, protective, or just a bystander has been a subject of debate. Recent advances in molecular and genetic works suggest Lewy bodies are not essential for the diagnosis and pathogenesis of Parkinson's disease. Furthermore, the discovery of gene mutations in PARK8, an autosomal-dominant late-onset parkinsonism with pleomorphic pathology, suggests the clinical expression of neurodegenerative diseases depends more on the anatomical pathways affected rather than any particular "pathological marker".