Variations in the sortilin gene have been implicated in the processing of amyloid precursor protein (APP) and essential tremor and variations in the SorCS2 gene have been shown to occur more frequently in bipolar disorder, schizophrenia and ADHD suggesting both sortilin and SorCS2 as important for normal CNS function [12–17]. The gene discussed is SORCS2; the disease is attention deficit-hyperactivity disorder.