Liver Detox Genes – CYP2A6

Liver DetoxGenesThis is part of an ongoing series on the genes involved in Phase I detoxification.

The CYP2A6 enzyme is involved in the metabolism of nicotine, several cancer drugs,  valproic acid, and coumarin. (Full list of drugs on Wikipedia). The hormone estradiol is an inducer of CYP2A6, and women usually have a somewhat higher activity of this enzyme.

It is thought that variant of CYP2A6 that cause decreased activity causes a lower level of dependence in smokers, making it easier for them to quit.  On the other hand, those with increased enzyme activity have an enhanced metabolism of nicotine and are likely to smoke more cigarettes per day.  [ref]

There are quite a few variations of CYP2A6.  Below are just a few that are available with 23andMe v.4 raw data.  For more information on CYP2A6 check out the PharmG KB site.

Check your 23andMe results for rs1801272: (note: 23andMe orientation – plus)

  • T/T: CYP2A6*2 – reduced activity [study]
  • A/T:  One CYP2A6*2 allele, reduced activity
  • A/A: normal


Check your 23andMe results for rs5031017:

  • A/A: CYP2A6*5 – non-functioning variant [study]
  • A/C:  One CYP2A6*5 allele, reduced activity
  • C/C: normal


Check your 23andMe results for rs5031016:

  • G/G: CYP2A6*7 – non-functioning variant [study]
  • A/G:  One CYP2A6*7 allele, reduced activity
  • A/A: normal


Check your 23andMe results for rs28399444:

  •  – – : CYP2A6*20 – non-functioning variant [study]
  • – I:  One CYP2A6*20 allele, reduced activity
  •  II: normal

Diet and Supplements:

Grapefruit juice contains a substance that inhibits CYP2A6 enzyme activity.  So be careful – especially if you have a slow variant of the gene – with combining grapefruit juice with any drug that is metabolized by CYP2A6.

More to read:


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