Yet, mutations in the remaining genes, although rare in frequency, have been unequivocally established as PD-causative and account for the majority of autosomal dominant (SNCA, LRRK2, HTRA2, and VPS35) or recessive PD cases (PRKN, PINK1, DJ-1, ATP13A2, PLA2G6, FBXO7, DNAJC6, and VPS13C). This evidence concerns the gene HTRA2 and Parkinson disease.