A rare autosomal recessive iron metabolism disorder characterized by iron deficiency anemia (hypochromic, microcytic) that is often unresponsive to oral iron intake and partially responsive to parenteral iron treatment. 50 patients from 32 families of different ethnic origin have been described to date; however, it is likely that this condition is underdiagnosed. Most IRIDA patients have no major clinical signs, except for pallor, and have normal growth and development. IRIDA syndrome is due to mutations the TMPRSS6 gene encoding Matriptase 2, a transmembrane serine protease that plays an essential role in down-regulating hepcidin, the key regulator of iron homeostasis. Transmission is autosomal recessive.