Given that substantial interest in the clinical relevance of IgSF9b has focused on its link to schizophrenia and major depression [17, 20, 21], we decided to focus our further investigations on regions known to contribute to encoding cognitive and affective behaviors, including SLM of hippocampal area CA1, MHb, LHb, and BLA. This evidence concerns the gene IGSF9B and major depressive disorder.