The prevalence of single nucleotide gene polymorphisms present in IL-8 (pro-inflammatory) and IL-10 (anti-inflammatory) cytokines is reported to be significantly increased not only in IBS patients but also in IBS patients positive for Blastocystis infection [44] suggesting that factors regulating the immune response in the host are important in expression of clinical disease. The gene discussed is CXCL8; the disease is irritable bowel syndrome.