ATXN2 and Parkinson disease: Until now, the nature of inheritance was precisely defined in several early-onset PD (EOPD) forms: autosomal dominantly inherited PD (AD-PD) is associated with the mutations of LRRK2, SNCA, VPS35, ATXN2, and GCH1 genes, autosomal recessive form of PD (AR-PD) with mutations of PRKN, PINK1, PARK7, ATP13A2, PLA2G6, FBXO7, DNAJC6, SPG11, SYNJ1, and VPS13C genes (Spatola and Wider, 2014; Lill, 2016; Lunati et al., 2018).