HTRA2 and Parkinson disease: At least 19 genetic loci for Parkinsonism have been identified to date, ten of which are autosomal dominant genes: SNCA (PARK1/PARK4), PARK3, UCHL1 (PARK5), LRRK2 (PARK8), GIGYF2 (PARK11), HTRA2 (PARK13), VPS35 (PARK17), EIF4G1 (PARK18), TMEM230 (PARK21), and CHCHD2 (PARK22).