A genetic predisposition is likely, at least in some cases of Parkinson disease. About 10% of patients have a family history of Parkinson disease. Several abnormal genes have been identified. Inheritance is autosomal dominant for some genes and autosomal recessive for others. A mutation in leucine-rich repeat kinase 2 (LRRK2; also known as PARK8) is a gene that codes for the dardarin protein. Worldwide, it is the most prevalent mutation in sporadic cases of Parkinson disease in patients ≥ 50 (in about 2%), and it is the most prevalent autosomal dominant mutation of the inherited forms of the disease.