(HealthDay)—The presence of multiple LRRK2 risk variants is associated with a younger age at onset (AAO) of Parkinson’s disease (PD), according to a research letter published online Nov. 13 in JAMA Neurology. Bin Xiao, M.D., Ph.D., from the National Neuroscience Institute in Singapore, and colleagues assessed 1,284 patients with PD for the LRRK2 risk variants S1647T, R1628P, and G2385R. The...