HMOX1 Gene

The HMOX1 gene (HMOX1 stands for "heme oxygenase 1") is a protein coding gene located on chromosome 22q12.3. The protein encoded by the HMOX1 gene, heme oxygenase (HO) catalyzes the degradation of heme. Heme oxygenase exists as 2 isoenzymes, an inducible heme oxygenase-1 and a constitutive heme oxygenase-2.

Heme oxygenase is a membrane-bound enzyme that cleaves the heme ring to produce bilverdin (which is further metabolized to bilirubin by bilirubin reductase), iron, and carbon monoxide.Heme oxygenase activity is induced by its substrate, heme, and by various non-heme substances.

Under physiological conditions, heme oxygenase activity is highest in the spleen, where senescent erythrocytes are sequestered and destroyed.

Diseases associated with HMOX1 include:

• Hem oxygenase 1 deficiency (OMIM: 614034)
• and
• Toxic encephalopathy.

1. Greil J et al. (2016) Mutating heme oxygenase-1 into a peroxidase causes a defect in bilirubin synthesis associated with microcytic anemia and severe hyperinflammation. (Letter) Haematologica 101: e436, 2016.
2. Gupta A et al. (2016) Haem oxygenase-1 deficiency: a mimicker of childhood vasculitis. (Letter) Scand. J Rheum 45: 165-170.
3. Kawashima A et al (2002) Heme oxygenase-1 deficiency: the first autopsy case. Hum Path 33: 125-130.
4. Radhakrishnan N et al (2011) Human heme oxygenase-1 deficiency presenting with hemolysis, nephritis, and asplenia. J Pediat Hemat Oncol 33: 74-78.