For example, microglia showed a reduced expression of Csmd1, a complement regulatory gene linked to familial epilepsy (Naseer et al, 2016) and schizophrenia (Schizophrenia Psychiatric Genome‐Wide Association Study & C, 2011), and of the protocadherin Pcdh9, which is a risk factor for major depressive disorder (Xiao et al, 2018). The gene discussed is PCDH11X; the disease is major depressive disorder.