Full Name: Heme Oxygenase 1

Genomic Location: Chromosome 22:35,380,361-35,394,214

Protein Size: 288 amino acids


Heme oxygenase cleaves the heme ring at the alpha methene bridge to form biliverdin. Biliverdin is subsequently converted to bilirubin by biliverdin reductase. Under physiological conditions, the activity of heme oxygenase is highest in the spleen, where senescent erythrocytes are sequestrated and destroyed. Exhibits cytoprotective effects since excess of free heme sensitises cells to undergo apoptosis.

Heme oxygenase, an essential enzyme in heme catabolism, cleaves heme to form biliverdin, which is subsequently converted to bilirubin by biliverdin reductase, and carbon monoxide, a putative neurotransmitter. Heme oxygenase activity is induced by its substrate heme and by various nonheme substances. Heme oxygenase occurs as 2 isozymes, an inducible heme oxygenase-1 and a constitutive heme oxygenase-2. HMOX1 and HMOX2 belong to the heme oxygenase family.

Linked SNP(s):

  • rs2071746 is linked to HMOX1, it is located approximately 150 bases upstream.
  • Population frequencies are approximately 50% for the reference allele (A) and 50% for the alternate allele (T).
  • Studies suggest the A allele is associated with restless leg syndrome.
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