In the past few years, mutations have been identified in the genes encoding alpha-synuclein, leucine-rich repeat kinase 2, and glucocerebrosidase in some patients with dementia with Lewy bodies (DLB). Furthermore, a novel locus for familial DLB has been mapped to chromosome 2q35-q36. Collectively, these discoveries highlight a substantial overlap between the known genetic determinants of Parkinson's disease and DLB, as well as the presence of profound etiologic heterogeneity in Lewy body disorders.