Considering the clinically probable DLB associated with the two core features of Parkinsonism and fluctuating cognition with deficits in attention, supported by an abundant tracer uptake in the right putamen and lower uptake in the left putamen on 123I-FP-CIT-SPECT as an indicative biomarker, we started an antidementia drug using a cholinesterase inhibitor. The gene discussed is BCHE; the disease is Lewy body dementia.