CD8A and immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome: Additionally, it appears that while CD8+Foxp3neg Treg do play a role in immune suppression they are not sufficient to solely maintain immune homeostasis and tolerance, as IPEX patients with Foxp3 mutations in both CD4+ and CD8+ Foxp3+ Treg populations experience severe immune dysregulation.