The combined DAT and 5HTT ligand 123I-N-ω-fluoropropyl-2βcarbomethoxy-3β-(4-iodophenyl) nortropane (123I-FP-CIT) has been used in DLB where the assumption is that cortical retention only represents 5HT innervation despite DA terminals being present. This evidence concerns the gene SLC6A3 and Lewy body dementia.