Effect of genotype on steady-state CYP1A1 gene expression in human peripheral lymphocytes

Abstract We have analyzed the steady-state levels of cytochrome P-450 1A1 (CYP1A1) mRNA in peripheral blood lymphocytes of 177 individuals with various CYP1A1 genotypes using a quantitative reverse transcriptase–polymerase chain reaction technique that makes use of a homologous internal standard for accurate quantitation. We found no effects of ethnicity, age, or smoking status on CYP1A1 gene expression in this population. We did see a significant 2-fold increase in the mean level of CYP1A1 mRNA in women compared with men for both Caucasians and African Americans. We observed no effect of the African American-specific polymorphism ( CYP1A1 ∗ 3 ) on expression of the gene. However, we found a significant 3-fold decrease in expression associated with the homozygous Msp I restriction fragment length polymorphism ( CYP1A1 ∗ 2A/ ∗ 2A ).