SYNJ1 and Parkinson disease: SYNJ1 (synaptojanin, MIM*604297) mutations cause another AR form of JOPD (PARK20, MIM#615530) characterized by motor PD features presenting at a median age of 21 years (range 12–31 years), poor response to levodopa treatment, early induced dyskinesias, gait disorders, and dysarthria/anarthria (159, 160).