Detection of a novel cytochrome P-450 1A2 polymorphism (F21L) in Chinese

Despite a wide interindividual variation of cytochrome P-450 1A2 (CYP1A2) a ctivity, genetic polymorphism of CYP1A2 has not been reported. By amplifica tion of exons of CYP1A2 by polymerase chain reaction in eight Chinese subje cts, the polymerase chain reaction products were directly sequenced. One su bject showed heterozygous C-2866-->G (Phe(21)-->Leu) polymorphism. DNA from 157 Chinese subjects (104 polychlorinated biphenyl-exposed subjects and 53 control subjects) was screened for polymorphism by single-strand conformat ion polymorphism method and Mboll endonuclease digestion. Only 1 of 157 sam ples showed another heterozygous C-2866-->G mutation. The subject was previ ously exposed to polychlorinated biphenyl and showed a value of 3.5% in the caffeine breath test. The value is not significantly higher than the mean value of polychlorinated biphenyl-exposed subjects (3.12 +/- 0.29%, mean +/ - S.E.M.). The incidence of the point mutation in these Chinese subjects is less than 1%. The prevalence of the F21L mutation in other ethnic groups a nd its effect on the metabolic activity of CYP1A2 remain to be further eval uated.