The aim of this study was to explore the expression pattern of NOS1AP in human tissues and its sequence variability in a large population of subjects (n = 280), including patients with schizophrenia (n = 72), ASD (n = 81) or OCD (n = 34), and in healthy volunteers controlled for the absence of personal or familial history of psychiatric disorders (n = 93). Here, NOS1AP is linked to Compulsive behaviors.