Genome-wide associated studies mapping 18 PD-related risk loci among PARK genes (PARK1-18), including autosomal dominant mutations in α-synuclein (PARK1, 4), UCHL1 (PARK5), LRRK2 (PARK8), HTRA2 (PARK13); while recessive mutations in Parkin (PARK2), PINK1 (PARK6), DJ-1 (PARK7), and ATP13A2 (PARK9) [reviewed in [58]]. Here, HTRA2 is linked to Parkinson disease.