These genetic, or familial, forms of PD result from a variety of autosomal dominant (LRRK2, GBA1, SNCA, VPS35) and autosomal recessive (PINK1, Parkin, DJ-1, ATP13A2, PLA2G6, VPS13C) mutations which typically present with earlier onset than sporadic PD [12]. This evidence concerns the gene LRRK2 and Parkinson disease.