Studies in humans have shown that TGF-β levels in plasma are decreased in patients with depression (Lin et al., 2024), while studies on mice models of stress have also detected decreased levels of TGF-β in the hippocampus (Baghaei Naeini et al., 2023) and basolateral amygdala (Zhong et al., 2022). The gene discussed is TGFB1; the disease is major depressive disorder.