肿瘤患者化疗药物相关单核苷酸多态性分布分析

目的探索我院肿瘤患者化疗药物相关单核苷酸多态性(SNPs)的分布特征,为临床药师开展以化疗药物相关SNPs为基础的肿瘤患者个体化用药指导提供参考。方法采用荧光原位杂交技术通过荧光标记的特异性探针检测化疗药物相关SNPs,回顾性分析北京大学肿瘤医院2016年4月~2018年12月肿瘤患者的化疗相关SNPs的分布特征。采用SPSS24.0软件统计相关基因位点的等位基因和基因型的频率分布差异,分析基因分布是否符合Hardy-Weinberg平衡。参照国外不同人群的基因型频率数据,探讨中国肿瘤患者化疗药物相关SNPs的分布特征。结果主要检测2554例肿瘤患者6大类化疗药物17个化疗药物相关基因位点,其中CYP2D6(100C>T)、ABCB1(2677T>G)不符合Hardy-Weinberg平衡,其余15个基因位点均符合Hardy-Weinberg平衡。DPD、CYP2D6、UGT1A1的SNPs与国外人群存在较大差异,与国内报道基本相符。结论中国肿瘤患者化疗药物相关SNPs分布有自身特点,临床药师应根据化疗药物相关SNPs提供个体化用药指导建议。基于药物基因组学的个体化用药,在参考PharmGKB等国际数据库的同时,国人的基因SNPs解读应结合国人的特点,不能完全参考国外人群数据库。     

Pharmacogenetics of immunosuppressant drugs: A new aspect for individualized therapy

In recent years, pharmacogenetics has emerged as an important tool for choosing the right immunosuppressant drug and its appropriate dose. Indeed, pharmacogenetics may exert its action on immunosuppressant drugs at three levels. Pharmacogenetics identifies and studies the genes involved in encoding the proteins involved in drug pharmacokinetics and in encoding the enzymes involved in drug degradation. Pharmacogenetics is also relevant in encoding the enzymes and proteins involved in codifying the transmembrane proteins involved in transmembrane passage favoring the absorption and intracellular action of several immunosuppressants. Pharmacogenetics concern the variability of genes encoding the proteins involved as immunosuppressant triggers in the pharmacodynamic pathways. Of course, not all genes have been discovered and studied, but some of them have been clearly examined and their relevance together with other factors such as age and race has been defined. Other genes on the basis of relevant studies have been proposed as good candidates for future studies. Unfortunately, to date, clear conclusions may be drawn only for those drugs that are metabolized by CYP3A5 and its genotyping before kidney, heart and lung transplantation is recommended. The conclusions of the studies on the recommended candidate genes, together with the development of omics techniques could in the future allow us to choose the right dose of the right immunosuppressant for the right patient.     

Pharmacogenetics and personalised medicine

The traditional concern of pharmacogenetics was Mendelian (monogenic) variation, which visibly affected some drug responses. Pharmacogenetics was broadened by the observation that multifactorial genetic influences, in conjunction with environmental factors, usually determine drug responses. Variability of gene expression, a new theme of the science of genetics, also affects pharmacogenetics; for example, enhanced enzyme activity does not necessarily indicate a mutation, but may be the consequence of a drug-induced enhancement of gene expression. Methodological advances permit the conversion of pharmacogenetics into the broad practice of pharmacogenomics; this improves the possibility of identifying genetic causes of common diseases, which means establishing new drug targets, thereby stimulating the search for new drugs. While the main medical effect of pharmacogenetics was an improvement of drug safety, pharmacogenomics is hoped to improve drug efficacy. On the way to personalized medicine, we may stepwise improve the chances of choosing the right drug for a patient by categorizing patients into genetically definable classes that have similar drug effects (as, for example, human races, or any population group carrying a particular set of genes). It is wise to expect that, even after we have reached the goal to establish personalized medicine, we will not have eliminated all uncertainties.     

Genetic polymorphisms of pharmacogenomic VIP variants in the lhoba population of southwest China

Background: It is well-established that differences among ethnic groups in drug responses are primarily due to the genetic diversity of pharmacogenes. A number of genes or variants that play a crucial role in drug responses have been designated Very Important Pharmacogenes (VIP) by the PharmGKB database. Clarifying the polymorphic distribution of VIPs in different ethnic groups will aid in personalized medicine for specific populations. Methods: We sequenced 85 VIP variants in the Lhoba population based on the PharmGKB database. The polymorphic distribution of the 85 VIP variants in 100 Lhoba subjects was determined and compared with that of 11 major HapMap populations, including ASW, CEU, CHB, CHD, GIH, JPT, LWK, MEX, MKK, TSI, and YRI. We used χ² tests to identify significantly different loci between these populations. We downloaded SNP allele frequencies from the ALlele FREquency Database to observe the global genetic variation distribution for these specific loci. And then we used Structure software to perform the genetic structure analysis of 12 populations. Results: Based on comparisons of selected available loci, we found that 23, 28, 16, 10, 20, 16, 24, 19, 22, 21 and 36 of the selected VIP variant genotype frequencies in the Lhoba population differed from those of the ASW, CEU, CHB, CHD, GIH, JPT, LWK, MEX, MKK, TSI, and YRI populations, respectively. In addition, Pairwise FST values and clustering analyses also showed the VIP variants in Lhoba exhibited a close genetic affinity with CHD, CHB and JPT populations. Conclusion: Our results complement pharmacogenomic data on the Lhoba ethnic group and may be helpful in the diagnosis of certain diseases in minorities.     

Gorgan (Turkmen in Iran) HLA genetics: transplantation,pharmacogenomics and anthropology

HLA class I and II alleles have been studied in a population from Gorgan (North East Iranian city bordering Turkmenistan). This population is composed of mainly Turkmen who speak Oghuz Turkish language. Comparison of Gorgan people HLA profile has been carried out with about 7984 HLA chromosomes from other worldwide populations; extended haplotypes and three dimension genetic distances have been calculated by using neighbor-joining and correspondence relatedness analyses. Most frequent extended HLA haplotypes show a Siberian/Mediterranean admixture and closest populations are Chuvashians (North Caspian Sea, Russia) and other geographically close populations like Siberian Mansi, Buryats and other Iranians. New extended HLA haplotypes have been found, such as: A*31:01-B*35:01-DRB1*15:01-DQB1*03:01, A*01:01-B*35:01-DRB1*03:01-DQB1*02:01. Relationships of Turkmen with Kurgan (Gorgan) archaeological mounds, Scythians and Sarmatians are discussed. This study is also useful for a future transplantation Gorgan waiting list, Gorgan HLA and disease epidemiology and HLA pharmacogenomics.     

Pharmacogenomics and personalized medicine: a review focused on their application in the Chinese population

The field of pharmacogenomics was initiated in the 1950s and began to thrive after the completion of the human genome project 10 years ago. Thus far, more than 100 drug labels and clinical guidelines referring to pharmacogenomic biomarkers have been published, and several key pharmacogenomic markers for either drug safety or efficacy have been identified and subsequently adopted in clinical practice as pre-treatment genetic tests. However, a tremendous variation of genetic backgrounds exists between different ethnic groups. The application of pharmacogenomics in the Chinese population is still a long way off, since the published guidelines issued by the organizations such as US Food and Drug Administration require further confirmation in the Chinese population. This review highlights important pharmacogenomic discoveries in the Chinese population and compares the Chinese population with other nations regarding the pharmacogenomics of five most commonly used drugs, ie, tacrolimus, cyclosporine A, warfarin, cyclophosphamide and azathioprine.