Objective: An apparent excess of sex chromosome aneuploidies (XXY, XXX, and possibly XYY) has been reported in patients with adult-onset schizophrenia and with unspecified psychoses. This study describes the results of cytogenetic screening carried out for pediatric patients meeting DMS-III-R criteria for childhood-onset schizophrenia (COS) and a subgroup of patients with childhood-onset psychotic disorder not otherwise specified, provisionally labeled by the authors as multidimensionally impaired (MDI).
Method: From August 1990 to July 1997, karyotypes were determined for 66 neuroleptic-nonresponsive pediatric patients (28 MDI, 38 COS), referred to the National Institute of Mental Health for an inpatient treatment trial of clozapine.
Results: Four (6.1%) of 66 patients (3 MDI, 1 COS) were found to have sex chromosome anomalies (mosaic 47,XXY; 47,XXY; 47,XYY; mosaic 45,XO, respectively), which is higher than the expected rate of 1 per 426 children or 2.34 per 1,000 in the general population (4/66 versus 1/426, chi 2 = 19.2, df = 1, p = .00001). All cases had been previously undiagnosed.
Conclusions: These findings lend support to a hypothesis that a loss of balance of gene products on the sex chromosomes may predispose affected individuals to susceptibility to additional genetic and environmental insults that result in childhood-onset psychotic disorders. Karyotyping of children with psychotic disorders should be routine.