Parkinsonism-Dystonia 2, Infantile-Onset, also known as brain dopamine-serotonin vesicular transport disease, is related to hypotonia and parkinsonism. An important gene associated with Parkinsonism-Dystonia 2, Infantile-Onset is SLC18A2 (Solute Carrier Family 18 Member A2). Affiliated tissues include brain and eye, and related phenotypes are abnormality of eye movement and ptosis