Chromosome 22q11.2 interstitial deletions among childhood-onset schizophrenics and "multidimensionally impaired".

Since its first description almost a century ago schizophrenia with childhood onset, a rare yet devastating disorder, has been diagnosed in children as young as age 5. Recently, the velocardiofacial syndrome, whose underlying cause is interstitial deletions of 22q11.2, was found in 2 of 100 cases of schizophrenics with adult onset [Karayiorgou et al., Proc Natl Acad Sci USA 92: 7612-7616, 1995]. No study has documented the prevalence of velocardiofacial syndrome and the 22q11.2 deletion in a population of schizophrenics with childhood onset. Here we describe the result of such a study in a sample originally selected for a trial of atypical antipsychotic drugs. A separate group of patients was also included in the study; they can best be accounted for as a variant of childhood-onset schizophrenia (COS) and had been provisionally termed "multidimensionally impaired." Fluorescent in situ hybridization screening of 32 COS and 21 multidimensionally impaired patients revealed 1 COS patient with an interstitial deletion spanning at least 2.5 megabases.