Conflicting findings have been reported for IFN-γ in pediatric samples with elevated levels seen in MDD (Gabbay et al., 2009a; Henje-Blom et al., 2012) and MDD with suicidal behavior (Gabbay et al., 2009b), but also reduced levels in MDD (Lee et al., 2020) and PTSD (Ayaydin et al., 2016). Here, IFNG is linked to major depressive disorder.