The ratio of the DA metabolite HVA to 5-HIAA was found to be augmented in cerebrospinal fluid (CSF) of DTDS patients compared to age-matched healthy patients, indicating increased striatal DA turnover at the extrasynaptic level due to the hyperdopaminergic state induced by the absence of DAT activity11, 13. The gene discussed is SLC6A3; the disease is SLC6A3-related dopamine transporter deficiency syndrome.