Recent studies have reported an increasing number of RAB39B mutations associated with early-onset PD as well as Lewy body diseases (LBDs) (Wilson et al., 2014; Lesage et al., 2015; Mata et al., 2015; Güldner et al., 2016; Shi et al., 2016; Ciammola et al., 2017). Here, RAB39B is linked to Lewy body dementia.