RAB39B and Parkinson disease: In addition, recent genome-wide association studies (GWASs) have proposed new loci associated with an increased risk of PD, which encode proteins involved in vesicular trafficking, such as VPS35, Synaptojanin1, VPS13C, Rab39B, Rab7L1/Rab29, and Synaptotagmin XI [13,19,20].