CRP and Parkinson disease: Differential regulation and clustering of protein expression provided further evidence for the enrichment for the complement pathway in Parkinson’s disease; a key element of the innate immune response that appears to be a common feature of multiple neurodegenerative diseases.24 Findings are consistent with previous work from the OPDC cohort showing that the most severely affected baseline Parkinson’s disease subtype was associated with a proinflammatory profile, comprising raised C-reactive protein and reduced APOEA1.25