RT Journal Article SR Electronic T1 Novel Mutations of CYP3A4 in Chinese JF Drug Metabolism and Disposition JO Drug Metab Dispos FD American Society for Pharmacology and Experimental Therapeutics SP 268 OP 273 VO 29 IS 3 A1 Kun-Pin Hsieh A1 Yen-Yu Lin A1 Ching-Ling Cheng A1 Ming-Liang Lai A1 Min-Shung Lin A1 Jean-Pascal Siest A1 Jin-Ding Huang YR 2001 UL http://dmd.aspetjournals.org/content/29/3/268.abstract AB Human cytochrome P450 3A4 is a major P450 enzyme in the liver and gastrointestinal tract. It plays important roles in the metabolism of a wide variety of drugs, some endogenous steroids, and harmful environmental contaminants. CYP3A4 exhibits a remarkable interindividual activity variation as high as 20-fold. To investigate whether the interindividual variation in CYP3A4 levels can be partly explained by genetic polymorphism, we analyzed DNA samples from 102 Chinese subjects by polymerase chain reaction (PCR)-single-strand conformation polymorphism analysis for novel point mutation in the CYP3A4 coding sequence and promoter region. Using PCR and directed sequencing method to establish the complete intron sequence ofCYP3A4 from leukocytes, the complete genomic sequence from exon 1 through 13 of CYP3A4 was determined and published in the GenBank database (accession no. AF209389). CYP3A4-specific primers were designed accordingly. After PCR-single-strand conformation polymorphism and restriction fragment length polymorphism screening, we found three novel mutations; two are point mutations and one is insertion. The first variant allele (CYP3A4*4), an Ile118Val change, was found in 3 of 102 Chinese subjects. The next allele (CYP3A4*5), which causes a Pro218Arg amino acid change, was found in 2 of 102 subjects. We found an insertion in A17776, designated asCYP3A4*6, which causes frame shift and an early stop codon in exon 9, in one heterozygous subject. We also investigated the CYP3A4 activity in these mutant subjects by measuring the morning spot urinary 6β-hydroxycortisol to free cortisol ratio with the enzyme-linked immunosorbent assay method. When compared with healthy Chinese population data, the 6β-hydroxycortisol to free cortisol ratio data suggested that these alleles (CYP3A4*4,CYP3A4*5, and CYP3A4*6) may decrease the CYP3A4 activity. Incidences of these mutations in Chinese subjects are rare. The prevalence of these point mutations in other ethnic groups and its effect on the metabolic activity of CYP3A4 remain to be further evaluated. The American Society for Pharmacology and Experimental Therapeutics