POLYMORPHIC DRUG OXIDATION--THE HUMAN CYP2D6 GENE

去氢异喹/司马汀的遗传多态是由突变的等位基因引起的 细胞色素P4502D6。缺乏这种细胞色素P450的个体是 不能代谢30多种药物。在一些情况下，缺乏 药物的新陈代谢导致毒性或夸大反应。关于 7.5%的高加索人拥有两个突变的CYP2D6等位基因。为了 鉴定这些突变基因，并努力开发出简单的 基于聚合酶链式反应的诊断试验--突变的CYP2D6等位基因 是直接从一个人的白细胞DNA中克隆出来的 不能代谢去氢异喹。该基因被完全测序，并 发现包含G到A的转变，从而改变了共识3素数 在CYP2D6基因内含子3和外显子4的交界处进行剪接。一个简单的 基于这种单一突变，开发了非放射性PCR检测， 它可以通过分析白细胞DNA来筛查个体 存在突变的P450基因。这个突变的等位基因被命名为CYP2D6(B)， 约占所有突变的CYP2D6基因的75%。 第二个突变基因，命名为CYP2D6(C)，被鉴定为 产生一种缺少单一氨基酸的蛋白质。这种酶是 具有催化活性，但在人体肝脏中不稳定表达。一个 建立了以聚合酶链式反应为基础的检测CYP2D6(C)的方法。 这是一种罕见的等位基因，占所有突变基因的不到2%。 互补的DNA表达系统已经被开发出来评估 CYP2D6代谢药物和激活化学致癌物的能力。 构建了含细胞色素P450 2D6 CDNA的淋巴母细胞系 证明烟草中发现的致癌物质的代谢活性 烟。

The debrisoquine/sparteine genetic polymorphism is due to mutant alleles of CYP2D6. Individuals lacking production of this cytochrome P450 are unable to metabolize over 30 drugs. In several instances, lack of metabolism of a drug results in toxicity or exaggerated responses. About 7.5% of Caucasians possess two mutant alleles of CYP2D6. In order to characterize these mutant genes and in an effort to develop simple polymerase chain reaction-based diagnostic tests, a mutant CYP2D6 allele was directly cloned from leukocyte DNA taken from an individual that was unable to metabolize debrisoquine. The gene was completely sequenced and found to contain a G to A transition that alters the consensus 3 prime splice site at the junction of intron 3 and exon 4 of CYP2D6. A simple non-radioactive PCR test was developed, based on this single mutation, that can be used to screen individuals by analyzing leukocyte DNA for presence of mutant P450 genes. This mutant allele, designated CYP2D6(B), represents about 75% of all mutant CYP2D6 genes. A second mutant CYP2D6 gene, designated CYP2D6(C), was identified that produces a protein lacking a single amino acid. This enzyme is catalytically active but is not stably expressed in human liver. A polymerase chain reaction-based test was also developed for CYP2D6(C). This is a rare allele representing less than 2% of all mutant genes. Complementary DNA expression systems have been developed to evaluate the ability of CYP2D6 to metabolize drugs and activate chemical carcinogens. A lymphoblastoid cell containing the CYP2D6 CDNA was constructed and used to demonstrate metabolic activation of a carcinogen found in tobacco smoke.