Heme oxygenase-1 deficiency (HMOX1D) is a rare autosomal recessive disorder characterized by intravascular haemolysis with peculiarly low bilirubin levels, nephritis, and features of systemic inflammation. It has been reported that mutations in HMOX1 cause this disease. HMOX1 encodes heme oxygenase-1, a rate-limiting enzyme catalysing the oxidation of heme to biliverdin, which is further converted to bilirubin. HMOX1 is rapidly induced in the liver, spleen, and endothelium following oxidative stress.
