Early onset parkinsonism

Early-onset parkinsonism refers to those patients with onset of a parkinsonian syndrome before age 40. These cases can be further subdivided into Young-onset (between ages 40 and 21) and Juvenile-onset (below age 21). In this review we will focus on the peculiar clinical features that distinguish these cases from classic late-onset parkinsonism, their characteristic response to medication, and their heterogeneous pathogenesis, including recent findings in the field of genetics that would suggest that a significant number of these patients are the result of genetic mutations.