Multiple mutations of the human cytochrome P450IID6 gene (CYP2D6) in poor metabolizers of debrisoquine. Study of the functional significance of individual mutations by expression of chimeric genes.

作者：Masaaki Kagimoto, Markus Hermann Heim, Keiko Kagimoto, Tanja Zeugin, Urs Meyer · 发表于：Journal of Biological Chemistry · 年份：1990 · DOI：10.1016/s0021-9258(17)44890-3 · 被引用次数：266 · 研究领域：Pharmacogenetics and Drug Metabolism、Cancer Treatment and Pharmacology、Computational Drug Discovery Methods

The debrisoquine/sparteine-type polymorphism is a clinically important inherited variation of drug metabolism characterized by two phenotypes, the extensive metabolizer and the poor metabolizer (PM). Five to 10 percent of individuals in Caucasian populations are of the PM phenotype and have deficient metabolism of debrisoquine and over 25 other drugs. Our previous studies have revealed absence of cytochrome P450IID6 protein and aberrant splicing of IID6 premRNA in livers of PMs. Moreover, two mutant alleles of the P450IID6 gene locus (CYP2D6) were identified by restriction fragment length analysis to be associated with the PM phenotype. However, the mutations of the CYP2D6 gene causing absent P450IID6 protein have not been defined. Here we report the cloning and sequencing of two types of mutant alleles of CYP2D6 isolated from genomic libraries of three PM individuals. One allele (29-A) was characterized by a single nucleotide deletion in the 5th exon with consequent frameshift and was observed in one individual only. The other type of mutant allele (29-B) was present in all three PM individuals and its sequence contained multiple mutations, notably four base changes causing amino acid changes in exons 1, 2 and 9, and a point mutation at the consensus sequence of the splice site of the 3rd intron. To understand the significance of the individual mutations, chimeric genes were constructed between the wild-type IID6 gene and the mutant 29-B allele or site-specific mutations wer...