TMPRSS6 and IRIDA syndrome: However, the main hepcidin inhibitor is type II transmembrane serine protease 6 (TMPRSS6 or matriptase-2), whose mutations are associated with a rare genetic disease named Iron-Refractory Iron Deficiency Anemia (IRIDA), characterized by iron deficiency and anemia due to constitutively and inappropriately high hepcidin levels [66].