A 4.5 Mb terminal deletion of chromosome 12p helps further define a psychosis-associated locus.

A 12 year-old girl presented with cognitive disability and dysmorphic features. Chromosome microarray analysis revealed a de novo, approximately 4.5 Mb terminal deletion of the short arm of chromosome 12 at 12p13.33 region: chr12:100712-4607067. At 13 years this patient developed psychotic manifestations and was admitted to a psychiatric department for treatment. She started hearing voices, talking to herself and laughing without reason. We have previously reported a male individual with psychotic manifestations and a larger (6.2 Mb) terminal deletion in the same chromosomal region. The present case along with previous reports, define a 2 Mb region on chromosome 12p, where a psychosis-associated gene may be located. Included in this psychosis-associated area are 18 OMIM listed genes.

Psychotic manifestations in a patient with mental retardation and a 6.2 megabase deletion at the distal short arm of chromosome 12.

Genetic factors are known to contribute to the development of schizophrenia and related psychoses. Cytogenetic abnormalities have been occasionally found in patients with psychotic disorders and, thus, have helped identify candidate gene contributors for these conditions. The individual described here first presented with mental retardation and anxiety disorder in his mid-childhood. In his early 20s, the patient started exhibiting various psychotic manifestations, including delusions and hallucinations. His psychotic symptoms were difficult to control with psychotropic medications. The family history was negative for psychiatric disorders. This patient was found to have a 6.2 megabase deletion of the terminal portion of the short arm of chromosome 12 that was characterized using fluorescence in situ hybridization and microarray comparative genomic hybridization analysis. The maternal chromosomes were normal, but the paternal chromosomes could not be tested. To-date such a chromosomal abnormality has not been described in association with schizophrenia/psychosis. This case suggests that psychosis-associated gene(s) may be located in the terminal region of the short arm of chromosome 12.