Have questions? Visit https://www.reddit.com/r/SNPedia

CYP2A6

From SNPedia

is agene
is mentioned by
Full namecytochrome P450, family 2, subfamily A, polypeptide 6
EntrezGene1548
PheGenI1548
VariationViewer1548
ClinVarCYP2A6
GeneCardsCYP2A6
dbSNP1548
SADR1548
HugeNav1548
CYPANCcyp2a6
wikipediaCYP2A6
googleCYP2A6
gopubmedCYP2A6
EVSCYP2A6
HEFalMpCYP2A6
MyGene2CYP2A6
23andMeCYP2A6
UniProtP11509
EnsemblENSG00000198077
OMIM122720
# SNPs12
 Max MagnitudeChromosome positionSummary
rs111033610040,847,036
rs1801272240,848,628
rs28399433240,850,474
rs28399444241,354,190
rs28399447041,352,941
rs28399454040,845,362
rs28399468040,843,827
rs4997557040,846,048
rs5031016040,843,869
rs5031017240,843,845
rs5611385040,847,202
rs56256500040,848,266

Some, but by no means most, of the individual variability in the rate at which nicotine is metabolized can be explained by CYP2A6 SNPs. Generally, smokers whose bodies rapidly metabolize nicotine will smoke more cigarettes, take in more cigarette smoke, and be more resistant to kicking the habit than slower metabolizers.

The most common CYP2A6 allele, CYP2A6*1, is considered to give rise to a fast metabolizing phenotype. Four relatively common CYP2A6 alleles are associated with slower metabolizers; they are CYP2A6*2, CYP2A6*4, CYP2A6*9, and CYP2A6*12. [PMID 17112802] CYP2A6*5 is a rare non-functioning variant. [PMID 15993850] The CYP2A6*20 variant results in a truncated protein and no enzyme activity.

To be more precise, the estimated percentage of CYP2A6 activity by genotype is as follows:

  • 100% activity (ie fast metabolizer): 2 copies of CYP2A6*1
  • 60-70% activity: 1 copy of CYP2A6*1 and 1 copy of either CYP2A6*9 or CYP2A6*12
  • 40-50% activity: either having:
    • 2 copies of CYP2A6*9 or CYP2A6*12 (or one of each), or
    • 1 copy of CYP1A6*1 and 1 copy of either CYP2A6*2 or CYP2A6*4
  • under 40% activity: either having:
    • 2 copies of CYP2A6*2 or CYP2A6*4 (or one of each), or
    • 1 copy of (CYP2A6*2 or *4) plus one of (*9 or *12)

The more common CYP2A6 alleles can be defined based on the following variations:

  • CYP2A6*1: (major alleles at variations listed below)
  • CYP2A6*2: rs1801272
  • CYP2A6*4: deletion of the CYP2A6 gene
  • CYP2A6*5: rs5031017 non-functioning variant
  • CYP2A6*9: rs28399433
  • CYP2A6*12: exons 1-2 from CYP2A7
  • CYP2A6*20: rs28399444 truncated non-functioning variant