Clinical genetics of Parkinson's disease and related disorders.

Our knowledge regarding the genetics of Parkinson's disease (PD) and parkinsonism has evolved dramatically during the past decade, with the discovery of numerous loci and genes. The LRRK2 gene has emerged as the most commonly involved in both familial and sporadic PD. Several variants in LRRK2 and SNCA have been associated with an increased risk of sporadic PD. PRKN, PINK1 and DJ1 mutations cause early-onset recessively inherited PD. Autosomal dominant dementia and parkinsonism is caused by mutations in the MAPT gene, and in the most recently discovered PGRN gene.