TABLE 3 

Linear regression analysis of CYP2A6 enzyme activity (cotinine formation from nicotine, nmol/min per milligram)a

Predictor VariableBBeta95% CI% Variation Accounted foreP Value
1) Model 1bCYP2A6*2 Genotypef−0.04−0.1−0.077 to –0.0011.0%<0.05
CYP2A6*9 Genotypef−0.03−0.1−0.059 to –0.0031.2%<0.05
CYP2A6*12 Genotypef−0.05−0.09−0.105 to 0.0040.8%<0.1
Gender (M = 1, F = 0)0.0040.02−0.02 to 0.030.03%>0.1
AKR1D1 mRNA (FPKM)0.0010.2<0.001 to 0.0013.3%<0.001
Age0.0010.2<0.001 to 0.0013.5%<0.001
POR Protein0.0040.50.003 to 0.00521.5%<0.001
2) Model 1 + CYP2A6 mRNAcCYP2A6*2 Genotypef−0.05−0.1−0.08 to –0.011.5%<0.01
CYP2A6*9 Genotypef−0.02−0.08−0.047 to 0.0050.5%>0.1
CYP2A6*12 Genotypef−0.04−0.07−0.09 to 0.010.4%>0.1
Gender (M=1, F=0)0.0030.02−0.02 to 0.020.03%>0.1
AKR1D1 mRNA (FPKM)<0.0010.07<0.001 to 0.0010.4%>0.1
Age0.0010.2<0.001 to 0.0012.6%<0.01
POR Protein0.0030.40.003 to 0.00414.0%<0.001
CYP2A6 mRNA (FPKM)<0.0010.4<0.001 to < 0.00110.0%<0.001
3) Model 1 + CYP2A6 mRNA + CYP2A6 proteindCYP2A6*2 Genotypef0.030.009−0.02 to –0.030.008%>0.1
CYP2A6*9 Genotypef<0.001<0.001−0.02 to 0.02<0.001%>0.1
CYP2A6*12 Genotypef0.0070.01−0.03 to 0.040.01%>0.1
Gender (M = 1, F = 0)0.0090.05−0.003 to 0.0220.2%>0.1
AKR1D1 mRNA (FPKM)<0.0010.02<0.001 to < 0.0010.04%>0.1
Age<0.0010.03<0.001 to < 0.0010.06%>0.1
POR Protein0.0010.09<0.001 to 0.0010.6%<0.05
CYP2A6 mRNA (FPKM)<0.0010.4<0.001 to < 0.0010.1%>0.1
CYP2A6 Protein0.0040.80.004 to 0.00531.9%<0.001
  • a Cases excluded pairwise.

  • b R2 = 0.35, P < 0.001

  • c R2 = 0.46, P < 0.001

  • d R2 = 0.77, P < 0.001

  • e % Variation accounted for by each variable is determined by: (Part Correlation)2 × 100.

  • f CYP2A6*2, CYP2A6*9, and CYP2A6*12 genotypes coded as 0 for CYP2A6*1/*1 genotype, 1 for CYP2A6*1/*2, CYP2A6*1/*9, or CYP2A6*1/*12 genotypes, and 2 for CYP2A6*2/*2 or CYP2A6*9/*9 genotypes.