DNA HealthDetoxification

NADP(H): Quinone Oxidoreductase

NQO1 609 C>T



NQO1 Gene Detail

NADP (H:) quinone oxidoreductase 1 (NQO1) often referred to as Quinone Reductase is primarily involved in the detoxification of potentially mutagenic and carcinogenic quinones derived from tobacco smoke, diet and oestrogen metabolism. NQO1 also protects cells from oxidative stress by maintaining the antioxidant forms of ubiquinone and vitamin E.



NQO1 609 C>T 

  • It is a Nrf2 target gene that encodes a cytoplasmic reductase enzyme which reduces reactive quinones to less reactive and less toxic hydroquinone’s along the Phase II detoxification pathway.
  • Its single cofactor is riboflavin-derived FAD.
  • The variant T allele results in reduced enzymatic activity.
  • Compared with the wildtype CC genotype, the heterozygote variant (CT) has a three-fold decrease in enzyme activity and the TT genotype has only 2%–4% of the quinone reductase activity
  • Individuals with the CT and TT genotype have been associated with an increased risk for developing certain cancers including breast, colorectal and gastrointestinal cancers, especially when there is exposure to cigarette smoke.
  • The polymorphism has also been linked to benzene toxicity
  • Risk allele = T



  • Cessation of smoking and avoidance of polycyclic aromatic hydrocarbons (PAHs) found in smoked foods and chargrilled meats.
  • Increase intake of cruciferous vegetables and possible supplementation with Sulphorofane (a compound found in broccoli) may be recommended.



The NQO1polymorphism C609T (Pro187Ser) and cancer susceptibility: a comprehensive meta-analysis

Lajin, 2013