RESUMO
Type 2 diabetes mellitus (T2DM) is a major global health problem. Response to first-line therapy is variable. This is partially due to interindividual variability across those genes codifying transport, metabolising, and drug activation proteins involved in first-line pharmacological treatment. Single nucleotide polymorphisms (SNPs) of genes SLC22A1, SLC22A2 and SLC22A3 affect metformin therapeutic response in patients with T2DM patients. The present study investigated allelic and genotypic frequencies of organic cation (OCT)1, OCT2, and OCT3 polymorphisms among metformin-treated patients with type 2 diabetes mellitus (T2DM). It also reports the association between clinical and genetic variables with glycated haemoglobin (HbA1c) control in 59 patients with T2DM. Patients were genotyped through real-time PCR (TaqMan assays). Metformin plasmatic levels were determined by mass spectrometry. Neither the analysis of HbA1c control by SNPs in SLC22A1, SLC22A2 and SLC22A3, nor the dominant genotypic model analysis yielded statistical significance between genotypes in polymorphisms rs72552763 (P=0.467), rs622342 (P=0.221), rs316019 (P=0.220) and rs2076828 (P=0.215). HbA1c levels were different in rs72552763 [GAT/GAT, 6.0 (5.7-6.6), GAT/del=6.5 (6.2-9.0), del/del=6.5 (6.4-6.8); P=0.022] and rs622342 [A/A=6.0 (5.8-6.5), A/C=6.4 (6.1-7.7), C/C=6.8 (6.4-9.3); P=0.009] genotypes. The dominant genotypic model found the lowest HbA1c levels in GAT/GAT (P=0.005) and A/A (P=0.010), in rs72552763 (GAT/GAT vs. GAT/del + del/del) and rs622342 (A/A vs. A/C + CC), respectively. There was a significant correlation between HbA1c levels and metformin dosage amongst del allele carriers in rs72552763 (ß1=0.14, P<0.001, r2=0.387), as opposed to GAT/GAT in rs72552763. There were no differences between HbA1c values in the test set and those predicted by machine learning models employing a simple linear regression based on metformin dosage. Therefore, rs72552763 and rs622342 polymorphisms in SLC22A1 may affect metformin response determined by HbA1c levels in patients with T2DM. The del allele of SNP rs72552763 may serve as a metformin response biomarker.
RESUMO
Interethnic variability in the drug-metabolizing capacity of CYP450 enzymes may lead to discrepancies in the relationship between genotypes and phenotypes worldwide. The present study was aimed to analyze for the first time whether there is a relationship between clinically relevant CYP450 genetic polymorphisms and their drug oxidation capacity (metabolic phenotype) in a population of healthy Nicaraguan volunteers. Two hundred and twelve participants were genotyped for CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4, and their actual metabolic phenotype (evaluated by the Metabolic Ratio, MR) was analyzed by using the CEIBA cocktail approach. The results showed the wide interindividual variability in all the studied enzymes and a significant difference (p < 0.004) in the activity of CYP1A2 between male and female subjects. The number of CYP2C19 (p < 0.0001) and CYP2D6 (p < 0.0001) active alleles were shown inversely correlated with their corresponding MR, although there were marked genotype-phenotype discrepancies. There was an actual enzyme capacity overlapping (MR) between genotypically Poor (gPMs) and Extensive Metabolizers (gEMs) of 3.14% subjects for CYP2D6 and 0.94% for CYP2C9. Similarly, there was an overlapping for metabolic phenotypes of 11.48% of genotypically ultrarapid metabolizers (gUMs) for CYP2C19 and 2.09% for CYP2D6 and gEMs. Therefore, the current approach for metabolic phenotype prediction based just on genotype does not predict properly for all individuals within this Nicaraguan Mestizo population, thus representing a potential barrier for the clinical implementation of personalized medicine in this region. However, it is necessary to improve the prediction of phenotype from genotype in order to improve the pharmacogenetic implementation in populations with specific ethnic backgrounds.
Assuntos
Sistema Enzimático do Citocromo P-450/genética , Adulto , Alelos , Feminino , Frequência do Gene/genética , Genótipo , Humanos , Masculino , Nicarágua , Farmacogenética/métodos , Fenótipo , Polimorfismo Genético/genética , Medicina de Precisão , Grupos Raciais/genética , Adulto JovemRESUMO
Background: Interethnic differences in CYP2D6 allele frequency have been demonstrated across Latin-American countries. Only one previous study describing CYP2D6 genotypes in Colombian population has been performed. Thus, this study aimed to evaluate the CYP2D6 genetic variability in a mestizo Colombian population, as well as the similarities and differences concerning other Hispanic mestizo (HM) populations. Methodology: Two hundred and twelve unrelated healthy Colombian subjects were studied, in which different CYP2D6 polymorphisms were analyzed by extra long-PCR and real-time PCR. Results & discussion: A high percentage of ultrarapid metabolizers (18.4%) was found, representing the highest frequency calculated within the HM populations studied. However, the percentage of poor metabolizers (4.7%) was similar to those previously reported in HM populations.
Assuntos
Indígena Americano ou Nativo do Alasca/genética , Citocromo P-450 CYP2D6/genética , Hispânico ou Latino/genética , Alelos , População Negra/genética , Colômbia/epidemiologia , Feminino , Frequência do Gene , Genótipo , Humanos , Masculino , Fenótipo , Polimorfismo Genético , PrevalênciaRESUMO
The majority of Mexican patients with diabetes mellitus type 2 (DMT2) (67.9-85.0%) are prescribed sulphonylureas (SUs), which are metabolized by cytochrome P450 2C9 (abbreviated as CYP2C9). SUs are a type of oral anti-diabetic compound which inhibit ATP-sensitive potassium channels, thus inducing glucose-independent insulin release by the ß-pancreatic cells. The wide variability reported in SU responses has been attributed to the polymorphisms of CYP2C9. The present study aimed to describe CYP2C9 polymorphisms (*2, *3 and IVS8-109T) within a sample of Mexican patients with DMT2, while suggesting the potential clinical implications in terms of glibenclamide response variability. From a sample of 248 patients with DMT2 who initially consented to be studied, those ultimately included in the study were treated with glibenclamide (n=11), glibenclamide combined with metformin (n=112) or metformin (n=76), and were subsequently genotyped using a reverse transcription-quantitative polymerase chain reaction (PCR), end-point allelic discrimination and PCR amplifying enzymatic restriction fragment long polymorphism. Clinical data were gathered through medical record revision. The frequencies revealed were as follows: CYP2C9*1/*1, 87.5%; *1/*2, 6.5%; *1/*3, 5.2%; and CYP2C9, IVS8-109A>T, 16.1%. Glibenclamide significantly reduced the level of pre-prandial glucose (P<0.01) and the percentage of glycated hemoglobin (%HbA1c; P<0.01) for IVS8-109A>T compared with combined glibenclamide and metformin treatment. Concerning the various treatments with respect to the different genotypes, the percentages obtained were as follows: Glibenclamide A/A, HbA1c<6.5=33.3%; glibenclamide + metformin A/A, HbA1c<6.5=24.6%; glibenclamide A/T, HbA1c<6.5=33.3%; glibenclamide + metformin A/T, HbA1c<6.5=25%; glibenclamide T/T, HbA1c<6.5=100%; and glibenclamide + metformin T/T, HbA1c<6.5=12.5%. Altogether, these results revealed that, although genetically customized prescriptions remain a desirable goal to increase the chances of therapeutic success, within the studied population neither allelic variants nor dosages demonstrated a clear association with biomarker levels. A key limitation of the present study was the lack of ability to quantify either the plasma concentrations of SU or their metabolites; therefore, further, precise experimental and observational studies are required.
RESUMO
Global precision medicine demands characterization of drug metabolism and phenotype variation in diverse populations, including the indigenous societies. A related question is the extent to which CYP450 drug metabolizing enzyme genotype and phenotype data are concordant and whether they can be used interchangeably. These issues are increasingly debated as precision medicine continues to expand as a popular research topic worldwide. We report here the first study in clinically relevant CYP450 drug metabolism phenotypes and genotypes in Mexican Amerindian indigenous subjects. In a large sample of 450 unrelated and medication free Mexican Amerindian indigenous healthy persons from four Mexican states (Chihuahua, Durango, Nayarit, and Sonora), we performed multiplexed phenotyping for the CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 drug metabolizing enzymes using the CEIBA cocktail and genotyped the same pathways for functional polymorphic variation. Remarkable interindividual variability was found for the actual drug metabolizing capacity of all the enzymes analyzed, and, more specifically, the metabolic ratios calculated were significantly different across individuals with different number of active alleles for CYP2C9, CYP2C19, and CYP2D6. The drug metabolizing capacity "predicted" from the genotype determined was not in accordance with the actual capacity "measured" by phenotyping in several individuals for CYP2C9, CYP2C19, and CYP2D6. Consequently, a more extensive genotyping of the main CYP enzymes, including rare variants, together with the analysis of the actual drug metabolizing capacity using an appropriate phenotyping approach will add valuable information for accurate drug metabolism studies, especially useful in understudied populations such as Mexican Amerindians. In sum, this study demonstrates that current personalized medicine strategies based on "predicted" phenotype from genotyping of alleles with high frequency in European populations are not adequate for Mestizos and Native American populations.
Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Medicina de Precisão/métodos , Citocromo P-450 CYP1A2/genética , Citocromo P-450 CYP1A2/metabolismo , Citocromo P-450 CYP2C19/genética , Citocromo P-450 CYP2C19/metabolismo , Citocromo P-450 CYP2C9/genética , Citocromo P-450 CYP2C9/metabolismo , Citocromo P-450 CYP2D6/genética , Citocromo P-450 CYP2D6/metabolismo , Citocromo P-450 CYP3A/genética , Citocromo P-450 CYP3A/metabolismo , Genótipo , Humanos , Fenótipo , Grupos PopulacionaisRESUMO
A long-standing question and dilemma in precision medicine is whether and to what extent genotyping or phenotyping drug metabolizing enzymes such as CYP2D6 can be used in real-life global clinical and societal settings. Although in an ideal world using both genotype and phenotype biomarkers are desirable, this is not always feasible for economic and practical reasons. Moreover, an additional barrier for clinical implementation of precision medicine is the lack of correlation between genotype and phenotype, considering that most of the current methods include only genotyping. Thus, the present study evaluated, using dextromethorphan as a phenotyping probe, the relationship between CYP2D6 phenotype and CYP2D6 genotype, especially for the ultrarapid metabolizer (UM) phenotype. We report in this study, to the best of our knowledge, the first comparative clinical pharmacogenomics study in a Cuban population sample (N = 174 healthy volunteers) and show that the CYP2D6 genotype is not a robust predictor of the CYP2D6 ultrarapid metabolizer (mUM) status in Cubans. Importantly, the ultrarapid CYP2D6 phenotype can result in a host of health outcomes, such as drug resistance associated with subtherapeutic drug concentrations, overexposure to active drug metabolites, and altered sensitivity to certain human diseases by virtue of altered metabolism of endogenous substrates of CYP2D6. Hence, phenotyping tests for CYP2D6 UMs appear to be a particular necessity for precision medicine in the Cuban population. Finally, in consideration of ethical and inclusive representation in global science, we recommend further precision medicine biomarker research and funding in support of neglected or understudied populations worldwide.