This case report presents a 26-year old female patient with 22q11.2 deletion syndrome, associated with psychiatric disorders. The patient was initially diagnosed with a neurodevelopmental disorder or schizophrenia and received treatment at several psychiatric institutions. Although she presented with various psychiatric symptoms of 22q11.2 deletion syndrome over her treatment course, the diagnosis was not recognized. Despite medication, she continued to experience hallucinations; delusions; and incoherent, explosive, and impulsive behavior. Her treatment was further complicated because she was also prone to adverse effects, suspected to be extrapyramidal symptoms. While investigating the possibility of treatment-resistant schizophrenia, the patient's history of congenital heart disease led to the first suspicion of 22q11.2 deletion syndrome, and genetic testing confirmed the diagnosis. Ideally, this syndrome is diagnosed in childhood; however, many case reports document adult patients who were first diagnosed when new psychotic symptoms appeared, and psychiatrists are likely to encounter undiagnosed adult patients. To the best of our knowledge, there are only seven reports to date of such cases from university hospitals and general hospital psychiatry departments in Japan, and this report is the first from an emergency psychiatric facility. Even in this setting, it is recommended to consider this syndrome in the differential diagnosis for patients with a history of congenital disease for whom treatment-resistant schizophrenia is suspected.
 Authors' abstract