Patients with Parkinson’s disease that carry GBA mutations also show a higher frequency of clinical features that are often associated with visual dysfunction in Parkinson’s disease: they have a higher risk of cognitive deficits (Neumann et al., 2009; Brockmann et al., 2011; Winder-Rhodes et al., 2013) and rapid eye movement (REM) sleep disorder than patients with idiopathic Parkinson’s disease (Beavan et al., 2015; Gan-Or et al., 2015) (see below for further discussion of clinical features associated with visual dysfunction in Parkinson’s disease). This evidence concerns the gene GBA1 and Parkinson disease.