VAMP4 and Parkinson disease: Finally, we investigated the possibility that there might be an interaction between the GWAS defined common LRRK2 risk allele (rs10878226) and VAMP4. We analyzed 4882 cases with PD carrying the LRRK2 risk variant minor allele using linear regression of AAO, and plotting of the Kaplan-Meier curve, as shown in Fig. 3.