Disorders of the basal ganglia and their modern management.

Parkinson’s disease (PD) is a common disorder, particularly among the elderly, with a prevalence of 100–200 per 100,000 in the general population1. In most patients, PD is sporadic, but rare genetic forms exist. Causative mutations have recently been identified on the a-synuclein gene on chromosome 4, responsible for Lewy body-positive , autosomal dominant PD, and the parkin gene on chromosome 6, responsible for Lewy body-negative autosomal recessive juvenile parkinsonism. An increased familial risk for PD has also been shown in monozygotic as opposed to dizygotic twins when onset is below the age of 502.