Cognitive and structural neuroimaging characteristics of schizophrenia patients with large, rare copy number deletions

• Structural and cognitive differences in schizophrenia patients compared with healthy controls.
• Greater cognitive impairments in schizophrenia patients with large, rare deletions.
• Grey-matter volume differences in schizophrenia patients with large, rare deletions.
• White-matter integrity differences in schizophrenia patients with large, rare deletions.

Large (>500 Kb), rare (frequency <1%) deletions are associated with risk for schizophrenia. The aim of the study was to characterise patients with these deletions using measures of cognition, grey-matter volume and white-matter integrity. Patients with schizophrenia and large, rare deletions (SZ-del) (n=17) were assessed on a test of intelligence, the Wechsler Abbreviated Scale of Intelligence (WASI), and compared with age- and sex-matched schizophrenia patients without large, rare deletions (SZ-nodel) (n=65), and healthy controls (HCs) (n=50). Regional grey-matter differences were investigated using voxel-based morphometry (SZ-del=9; SZ-nodel=26; HC=19). White-matter integrity was assessed using fractional anisotropy (SZ-del=9; SZ-nodel=24; HC=15). Compared with schizophrenia patients without large, rare deletions, those with large, rare deletions had lower IQ; greater grey-matter volume in clusters with peaks in the left and right cerebellum, left hippocampus, and right rectal gyrus; and increased white-matter anisotropy in the body and genu of the corpus callosum. Compared with healthy controls, patients with large, rare deletions had reduced grey matter volume in the right calcarine gyrus. In sum, patients with large, rare deletions had structural profiles intermediate to those observed in healthy controls and schizophrenia patients without large, rare deletions, but had greater impairment in intelligence.