LRRK2 and Parkinson disease: In addition, recent studies suggest that antigen presentation is altered in a subset of individuals with PD in association with a non-coding SNP (rs 3129882) in the MHC-II locus that synergizes with environmental exposures to increase risk for PD.45 Although the LRRK2 and MHC-II loci are encoded on different chromosomes, perhaps the mechanism of altered antigen presentation increases susceptibility for sporadic PD.