CCR2 and Parkinson disease: Disease-associated genetic variants of IL-8/CXCL8 (-251A/T), MCP-1/CCL2 (-2518G/A), RANTES/CCL5 (-28C/G), CCR2 (V64I), and CCR5 (-delta32) have been studied in different populations and ethnic groups with PD and late onset AD [6, 14].