HTRA2 and Parkinson disease: The aim of this study was to assess the co-occurrence of rare variants, possibly in haplotype, in the set of genes associated with parkinsonism (ADH1C, EIF4G1, FBXO7, GBA, GIGYF2, HTRA2, LRRK2, MAPT, PARK2, PARK7, PINK1, PLA2G6, SNCA, UCHL1, and VPS35) in the parkinsonian patients and controls from the Hornacko region [36,37,38].