A genetic polymorphism in the regulatory sequences of human CYP2E1: association with increased chlorzoxazone hydroxylation in the presence of obesity and ethanol intake.

To pursue the hypothesis that differences in the regulatory region of CYP2E1 are partially responsible for the intersubject variation in in vivo CYP2E1 activity, restriction enzyme digestion and Southern blotting of 36 human DNA samples were performed. The fractionated DNA was hybridized with a genomic probe to the upstream region of CYP2E1 from positions -2710 to -580. After digestion with the restriction enzyme XbaI, most subjects (69%) were homozygous for the expected band representing the XbaI fragment from positions -2270 to -408, whereas 31% had an unexpected, slightly larger band.