MDD has also been shown to be associated with abnormalities in lymphocytes including increased number of CD4+ T cells and a reduction of regulatory B cells and regulatory T cells, indicating an imbalance in the adaptive immune system (Ahmetspahic et al., 2018; Foley et al., 2023; Li et al., 2010; Lynall et al., 2020), which is in line with the concordant effect directions found among lymphocytes in our bivariate MiXeR analysis. This evidence concerns the gene CD4 and major depressive disorder.