GBA1 and Parkinson disease: PD patients harboring mutations in GBA1 exhibit varied phenotypes based on the severity of the mutation, but generally present with a slightly earlier age of onset and greater prevalence of cognitive changes compared to patients without GBA1 mutations (Alcalay et al., 2010; Nichols et al., 2009; Neumann et al., 2009; Sidransky et al., 2009).