The 2017 DLB Consortium criteria diagnose probable DLB if there are two or more core clinical features, or one core feature plus an indicative biomarker (reduced striatal dopamine-transporter uptake (positron emission tomography/single-photon emission computed tomography, PET/SPECT), reduced myocardial iodine-123-metaiodobenzylguanidine (MIBG) uptake, or polysomnographic confirmation of rapid eye movement (REM) sleep without atonia) [22,50,51]. The gene discussed is SLC6A3; the disease is Lewy body dementia.