SLC6A4 and Timothy syndrome: In TS, only three neuroimaging studies aimed to investigate the availability of serotonin transporters (SERT) using either [123I]ß-carbomethoxy-3ß-(4-iodophenyl)tropane ([123I]ß-CIT) and single-photon emission tomography (SPECT)1,2 or [11C]McN5652 and positron emission tomography (PET)3.