Later on, multicenter studies recruiting several thousands of patients revealed that GBA1 mutations are the most common genetic risk factor for developing PD (Sidransky et al., 2009; Velayati et al., 2010) In fact, a marked incidence of GBA1 mutations has been found in familial forms of PD (Mitsui et al., 2009; Nichols et al., 2009) as well as in up to 17% of PD patients that underwent deep brain stimulation (Angeli et al., 2013). This evidence concerns the gene GBA1 and Parkinson disease.