The effect of the CYP1A2 *1F mutation on CYP1A2 inducibility in pregnant women

Br J Clin Pharmacol. 2002 Nov;54(5):504-10. doi: 10.1046/j.1365-2125.2002.01673.x.


Aims: To investigate the influence of the CYP1A2*1F mutation on CYP1A2 activity in smoking and nonsmoking pregnant women.

Methods: Pregnant women (n = 904) who served as control subjects in a case-control study of early fetal loss were investigated. They were phenotyped for CYP1A2 using dietary caffeine and the urinary ratio AFMU + 1X + 1 U/1,7 U. An assay for CYP1A2*1F using 5'-nuclease assay (Taqman) was developed to genotype the population.

Results: The frequencies of *1 A and *1F alleles among Swedish women were 0.29 and 0.71, respectively. There was no statistically significant difference in CYP1A2 activity between the genotypes, although a trend towards enhanced activity was observed in *1F/*1F (log MRc 0.77) and *1F/*1 A (log MRc 0.82) genotypes compared with the *1 A/*1 A genotype (log MRc 0.71) (anovaP = 0.07). The mean difference between the *1 A homozygotes and the heterozygotes was 0.11 [95% confidence interval of the difference: (-0.21, -0.01)] and that between the *1 A and *1F homozygotes was 0.05 [95% confidence interval of the difference: (-0.13, 0.03)]. No significant effect (P = 0.22) of the *1F on CYP1A2 activity was observed in smokers, tested using an interaction term (smoking * genotype) in the anova model (*1F/*1F log MRc 0.79, *1F/*1 A log MRc 0.86, and *1 A/*1 A log MRc 0.73). In smokers, there was no difference in ratio between homozygotes for the *1 A and *1F alleles [mean difference -0.06; 95% confidence interval of the difference: -0.22, 0.11] or between *1 A/*1 A and *1 A/*1F genotypes [mean difference -0.13; 95% confidence interval of the difference: -0.29, 0.04].

Conclusions: The effect of the CYP1A2*1F mutation on CYP1A2 activity in smoking pregnant women could not be confirmed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Analysis of Variance
  • Case-Control Studies
  • Cytochrome P-450 CYP1A2 / genetics*
  • Female
  • Gene Frequency
  • Genotype
  • Humans
  • Mutation / genetics*
  • Polymerase Chain Reaction / methods
  • Pregnancy / genetics*
  • Smoking / genetics*


  • Cytochrome P-450 CYP1A2