A meta-analysis of 27 of these studies, involving 1,286 patients with depression and 991 controls, found that compared with controls, patients with depression have significantly higher absolute counts of CD4+ T cells, significantly lower relative counts of Th1 and Th2, and significantly higher mean absolute counts of B lymphocytes (Foley É et al., 2023). The gene discussed is CD4; the disease is major depressive disorder.