Classic Dopamine Transporter Deficiency Syndrome describes a subset of SLC6A3-related DTDS cases which present in early infancy. This disorder is usually first identified by neonatal distress and irritability, feeding difficulties, and motor developmental delay. The disease is MONDO_0054835 (classic dopamine transporter deficiency syndrome). Also known as: PKDYS1, Parkinsonism-dystonia, infantile, 1, classic DTDS.