With the exclusion of PRKN mutations, responsible for 77% of juvenile PD (see section Other Movement Disorder Genes Possibly Manifesting as AD PD) and the extremely rare PODXL-related cases, more than 90% of patients have a complex or atypical presentation, with dystonia, pyramidal signs, neuropsychiatric disorders, abnormal eye movements, and brain imaging. The gene discussed is PRKN; the disease is Parkinson disease.