Genetic susceptibility variants in parkinsonism.

Parkinsonism is an umbrella term for a group of disorders characterized by the clinical signs of tremor, bradykinesia, rigidity, and postural instability. On neuropathologic examination parkinsonism can display alternate protein pathologies (e.g. α-synucleinopathy or tauopathy) but the degeneration of nigral neurons is consistent. The main forms of parkinsonism are, Parkinson's disease (PD), Dementia with Lewy Bodies (DLB), Multiple System Atrophy (MSA), Progressive Supranuclear Palsy (PSP) and Corticobasal Degeneration (CBD). Genetic studies from candidate gene, to unbiased genome-wide approaches including association and next-generation sequencing have nominated a number of disease determinants. Within this review we will highlight the genetic loci that are associated with disease and discuss the implications and importance for a better understanding of the genes involved and thus the underlying pathophysiology of these disorders.