22q11.2 deletion syndrome (22q11.2 DS) is characterized by cardiac defects, abnormal facial features, thymic hypoplasia, cleft palate, and hypocalcemia, including DiGeorge syndrome (DGS), velocardiofacial syndrome (VCFS), and conotruncal anomaly face (CTAF) syndrome. Psychiatric symptoms were recently shown to be very common in patients with 22q11.2 DS, prompting greater interest in this syndrome. Early diagnosis during childhood based on a constellation of physical features is optimal; however, as some patients remain undiagnosed until the presentation of other symptoms in adult life, psychiatrists are well advised to familiarize themselves with basic information concerning 22q11.2 DS.
 A 25-year-old woman presenting with auditory hallucinations was referred to A hospital for examination and treatment. Her family history revealed both paternal and maternal relatives with schizophrenia. At birth, she presented a cleft palate and ventricular septum defect. She first became ambulatory at age 4 and became verbal a year later. Her intelligence quotient was estimated at around 40 and mental retardation (DSM-IV) with autistic features was diagnosed at age 7. After graduating from a special high school, she obtained fulltime employment in a workshop. However, auditory hallucinations began disrupting her life from 22 years of age. Although olanzapine temporarily alleviated her symptoms, the resultant extrapyramidal symptoms worsened and she was referred to A hospital again at age 25. The patient presented with micrognathia and a flat nasal root and spoke a maximum of 3 words per sentence in a very high and indistinct tone. A cardiac defect (ventricular septal defect), scoliosis, and low platelets were also observed. The diagnosis of 22q11.2 DS was confirmed using fluorescence in situ hybridization (FISH). The patient and her family were subsequently introduced to a 22q11.2 DS patients' support group. Careful genetic counseling is paramount, but the diagnosis of 22q11.2 DS can make updated information, official aid, and access to support groups available to patients and their family. Emergency complications such as seizures due to hypocalcemia can also be anticipated.
 The comparatively late diagnosis of 22q11.2 DS in our patient, which went undetected until the presentation of auditory hallucinations, in the context of mental retardation with autistic features (DSM-IV) underscores the importance of detailed clinical observation. "One rare variant" possibly points out the essence of psychiatric pathophysiology. Moreover, 22q11.2 DS has been listed as an intractable disease in Japan since 2015. When patients present with neurodevelopmental disorders and schizophrenic symptoms, we should carefully observe their physical features for clues to the possible diagnosis of 22q11.2 DS.
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