Dopamine transporter (DAT) single-photon emission computed tomography (SPECT) is an imaging modality that can effectively differentiate neurodegenerative parkinsonian syndromes (PS), including Parkinson’s disease (PD) and dementia with Lewy bodies (DLB) from other neurological disorders not characterized by dopaminergic degeneration, such as Alzheimer disease, drug-induced Parkinsonism, and essential tremor [1, 2]. The gene discussed is SLC6A3; the disease is early-onset autosomal dominant Alzheimer disease.