Parkinson Disease: Epidemiology, Pathology, and Clinical Diagnosis
- The contribution of genetics to Parkinson disease (PD) is suggested by the increased risk of disease associated with a family history, and community-based studies that found a 1.5- to threefold increased risk of PD in persons with an affected first-degree relative. However, the most convincing evidence to date has come with the discovery of monogenic forms of PD. Highly penetrant mendelian forms of PD have now been associated with mutations in different genes but, in most populations, causative mutations in these genes have been found in fewer than 5% of patients. Nevertheless, different variants with incomplete penetrance in the LRRK2 and the GBA gene are strong risk factors for PD, and are especially prevalent in some populations. Mutations of the GBA gene are indeed the most important risk factor yet discovered for PD; the presence of a GBA mutation in homozygous or heterozygous form is associated with an approximately 20-fold increase in the risk for PD.







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