About 30% of familial and 3–5% of the sporadic PD cases are monogenic forms that derive from a single mutation in a gene that can be inherited dominantly, such as SNCA and LRRK2 (also known as PARK8) or recessively, such as PARK2, PINK1 (also known as PARK7) and ATP13A2 (also known as PARK9) [20]. Here, SNCA is linked to Parkinson disease.