In a previous study of 13 children with ASD and 9 with ASD + ADHD, those with comorbid ADHD had increased levels of proinflammatory cytokine MIF and decreased levels of chemokine IL-8, while children with ASD only showed increased levels of MCP-1 compared to typically developing controls (16). This evidence concerns the gene CXCL8 and attention deficit-hyperactivity disorder.