Karyotype analysis of 161 unrelated schizophrenics: no increased rates of X chromosome mosaicism or inv(9), using ethnically matched and age-stratified controls

Chromosomal aberrations have long been studied in an effort to identify sus ceptibility genes in schizophrenia. The two most frequently detected abnorm alities are X chromosome mosaicism in female patients and pericentric inver sions of chromosome 9 [inv(9)]. Chromosome X aneuploidies are known to be a ge dependent but differences due to ethnicity remain undetermined. ln the c ase of inv(9). its prevalence in the general population varies with ethnici ty. To evaluate the importance of these karyotypic changes in schizophrenia , cytogenetic analysis was performed on 161 unrelated schizophrenics of Jap anese origin. We observed an increase in the incidence of X chromosome mosa icism in female schizophrenics with age. However, when compared with age ma tched female controls (92 individuals), no significant differences between patient and control samples were detected. Moreover, this study showed that there is no significant difference in the incidence of X chromosome loss b etween Japanese and Caucasian populations. The four cases with inv(9) (2.5% ) detected in this study, did not differ significantly from the reported in cidence of between 1.7 and 2.1 % seen in the general Japanese population. W e also observed a small number of additional karyotypic changes, none of wh ich were recurrent. This is the first report to examine the comparative rat es of X mosaicism in female schizophrenics and age matched controls. (C) 20 01 Elsevier Science B.V. All rights reserved.