A recent large-scale magnetic resonance imaging data analysis showed that patients with schizophrenia had small hippocampi compared with healthy controls and that hippocampal volume deficits were significantly associated with a high proportion of unmedicated patients.30 The aberrant hippocampal volume could be partially ameliorated by atypical antipsychotic treatment.31 Allen et al.32 measured adult hippocampal neurogenesis in patients with schizophrenia and observed that the cell proliferation marker Ki67 was significantly reduced in their postmortem hippocampal tissues. This evidence concerns the gene MKI67 and schizophrenia.