The genes encoding type I interferons (IFNs), which include 14 IFN-alpha genes, 1 IFN-beta gene, 1 IFN-gamma (also known as IFN-alphaII1) gene, and a number of IFN-gamma pseudogenes, are clustered on human chromosome 9. Interferons-alpha and -beta are cytokines that are widely known to induce potent antiviral activity. IFN-alpha and -beta exert a variety of other biological effects, including anti-tumor and immunomodulatory activities, and are increasingly used clinically to treat a range of malignancies, myelodysplasias and autoimmune diseases.