One study compared the levels of the proinflammatory cytokines chemokine C-C motif ligand 5 (CCL-5), monocyte chemoattractant protein-1 (MCP-1) and stromal derived factor-1 (SDF-1) in 120 medication-naïve, physically well patients with a diagnosis of GAD and comorbid personality disorder with 40 controls.48 Significantly higher levels of MCP-1 and SDF-1 were reported in both men and women, and higher CCL-5 in men but not women with a diagnosis of GAD compared with controls.48 This evidence concerns the gene CCL5 and generalized anxiety disorder.