SLC6A3 and SLC6A3-related dopamine transporter deficiency syndrome: Mutations in the human dopamine (DA) transporter (hDAT) gene (SLC6A3) have been linked to a distinct type of infantile parkinsonism-dystonia, referred to as DA transporter deficiency syndrome (DTDS) (Kurian et al., 2011; Kurian et al., 2009; Ng et al., 2014).