Lateral ventricular enlargement in schizophrenic probands and their siblings with schizophrenia-related isorders

To investigate possible genetic determinants of ventricular enlargement in schizophrenia, we compared lateral ventricle/brain ratios (VBRs) in schizophrenic patients with their own siblings, some with and some without other schizophrenia-related disorders [e.g., schizotypal personality disorder (SPD)], as well as with a group of unrelated normal controls. Methods: VBRs, measured by computed tomography, were compared in both groupwise and within-sibship analyses, the latter method providing a measure of control over familial/genetic factors related to VBR, but unrelated to schizophrenia. Results: The VBRs were significantly different across the groups, but the only significant pairwise group comparison was between the schizophrenia and no-SRD family member groups. In the within-sibship analyses, however, the VBRs of those with SPD and schizophrenia were similar, and both groups had significantly larger VBRs than their own siblings without SRD. In addition, siblings with a negative family history for SRD had larger VBRs than family history positive siblings. Conclusions: The results suggest that specific schizophrenia-related genetic factors may help determine ventricular enlargement in familial schizophrenia. The larger VBRs in family history negative siblings might be attributable to genetic factors not specifically associated with schizophrenia, but which nevertheless increase its susceptibility.