- MDD patients had: ​ ● Lower T-cell surface expression of the chemokine receptors CXCR3 and CCR6 ​ ● Higher frequency of CD4+CD25highCD127low/− cells ​ ● Increased FOXP3 mRNA expression in purified CD4+ T cells ​ ● Less diverse library of CD4+ T cells. The gene discussed is CCR6; the disease is major depressive disorder.