The need to diversify genomic studies: Insights from Andean highlanders and Amazonians.

More globally diverse perspectives are needed in genomic studies and precision medicine practices on non-Europeans. Here, we illustrate this by discussing the distribution of clinically actionable genetic variants involved in drug response in Andean highlanders and Amazonians, considering their environment, history, genetic structure, and historical biases in the perception of biological diversity of Native Americans.

Pharmacogenomic biomarker information on drug labels of the Spanish Agency of Medicines and Sanitary products: evaluation and comparison with other regulatory agencies.

This work aimed to analyse the pharmacogenetic information in the Spanish Drug Regulatory Agency (AEMPS) Summary of Products Characteristics (SmPC), evaluating the presence of pharmacogenetic biomarkers, as well as the associated recommendations. A total of 55.4% of the 1891 drug labels reviewed included information on pharmacogenetic biomarker(s). Pharmacogenomic information appears most frequently in the "antineoplastic and immunomodulating agents", "nervous system", and "cardiovascular system" Anatomical Therapeutic Chemical groups. A total of 509 different pharmacogenetic biomarkers were found, of which CYP450 enzymes accounted for almost 34% of the total drug-biomarker associations evaluated. A total of 3679 drug-biomarker pairs were identified, 102 of which were at the 1A level (PharmGKB® classification system), and 33.33% of these drug-pharmacogenetic biomarker pairs were assigned to "actionable PGx", 12.75% to "informative PGx", 4.9% to "testing recommended", and 4.9% to "testing required". The rate of coincidence in the assigned PGx level of recommendation between the AEMPS and regulatory agencies included in the PharmGKB® Drug Label Annotations database (i.e., the FDA, EMA, SWISS Medic, PMDA, and HCSC) ranged from 45% to 65%, being 'actionable level' the most frequent. On the other hand, discrepancies between agencies did not exceed 35%. This study highlights the presence of relevant pharmacogenetic information on Spanish drug labels, which would help avoid interactions, toxicity, or lack of treatment efficacy.

Relationships between CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 metabolic phenotypes and genotypes in a Nicaraguan Mestizo population.

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.

Influence of genetic variants and antiepileptic drug co-treatment on lamotrigine plasma concentration in Mexican Mestizo patients with epilepsy.

Genetic and nongenetic factors may contribute to lamotrigine (LTG) plasma concentration variability among patients. We simultaneously investigated the association of UGT1A1, UGT1A4, UGT2B7, ABCB1, ABCG2, and SLC22A1 variants, as well as antiepileptic drug co-treatment, on LTG plasma concentration in 97 Mexican Mestizo (MM) patients with epilepsy. UGT1A4*1b was associated with lower LTG dose-corrected concentrations. Patients with the UGT2B7-161T allele were treated with 21.22% higher LTG daily dose than those with CC genotype. Two novel UGT1A4 variants (c.526A>T; p.Thr185= and c.496T>C; p.Ser166Leu) were identified in one patient. Patients treated with LTG + valproic acid (VPA) showed higher LTG plasma concentration than patients did on LTG monotherapy or LTG + inducer. Despite the numerous drug-metabolizing enzymes and transporter genetic variants analyzed, our results revealed that co-treatment with VPA was the most significant factor influencing LTG plasma concentration, followed by UGT1A4*1b, and that patients carrying UGT2B7 c.-161T required higher LTG daily doses. These data provide valuable information for the clinical use of LTG in MM patients with epilepsy.

Genetic structure of pharmacogenetic biomarkers in Brazil inferred from a systematic review and population-based cohorts: a RIBEF/EPIGEN-Brazil initiative.

We present allele frequencies involving 39 pharmacogenetic biomarkers studied in Brazil, and their distribution on self-reported race/color categories that: (1) involve a mix of perceptions about ancestry, morphological traits, and cultural/identity issues, being social constructs pervasively used in Brazilian society and medical studies; (2) are associated with disparities in access to health services, as well as in their representation in genetic studies, and (3), as we report here, explain a larger portion of the variance of pharmaco-allele frequencies than geography. We integrated a systematic review of studies on healthy volunteers (years 1968-2017) and the analysis of allele frequencies on three population-based cohorts from northeast, southeast, and south, the most populated regions of Brazil. Cross-validation of results from these both approaches suggest that, despite methodological heterogeneity of the 120 studies conducted on 51,747 healthy volunteers, allele frequencies estimates from systematic review are reliable. We report differences in allele frequencies between color categories that persist despite the homogenizing effect of >500 years of admixture. Among clinically relevant variants: CYP2C9*2 (null), CYP3A5*3 (defective), SLCO1B1-rs4149056(C), and VKORC1-rs9923231(A) are more frequent in Whites than in Blacks. Brazilian Native Americans show lower frequencies of CYP2C9*2, CYP2C19*17 (increased activity), and higher of SLCO1B1-rs4149056(C) than other Brazilian populations. We present the most current and informative database of pharmaco-allele frequencies in Brazilian healthy volunteers.

A Pharmacovigilance Study in First Episode of Psychosis: Psychopharmacological Interventions and Safety Profiles in the PEPs Project.

BACKGROUND: The characterization of the first episode of psychosis and how it should be treated are principal issues in actual research. Realistic, naturalistic studies are necessary to represent the entire population of first episode of psychosis attended in daily practice. METHODS: Sixteen participating centers from the PEPs project recruited 335 first episode of psychosis patients, aged 7 to 35 years. This article describes and discusses the psychopharmacological interventions and safety profiles at baseline and during a 60-day pharmacovigilance period. RESULTS: The majority of first episode of psychosis patients received a second-generation antipsychotic (96.3%), orally (95%), and in adjusted doses according to the product specifications (87.2%). A total of 24% were receiving an antipsychotic polytherapy pattern at baseline, frequently associated with lower or higher doses of antipsychotics than the recommended ones. Eight patients were taking clozapine, all in monotherapy. Males received higher doses of antipsychotic (P=.043). A total of 5.2% of the patients were being treated with long-acting injectable antipsychotics; 12.2% of the patients received anticholinergic drugs, 12.2% antidepressants, and 13.7% mood stabilizers, while almost 40% received benzodiazepines; and 35.52% reported at least one adverse drug reaction during the pharmacovigilance period, more frequently associated with higher antipsychotic doses and antipsychotic polytherapy (85.2% vs 45.5%, P<.001). CONCLUSIONS: These data indicate that the overall pharmacologic prescription for treating a first episode of psychosis in Spain follows the clinical practice guideline recommendations, and, together with security issues, support future research of determinate pharmacological strategies for the treatment of early phases of psychosis, such as the role of clozapine, long-acting injectable antipsychotics, antipsychotic combination, and the use of benzodiazepines.

Success stories in genomic medicine from resource-limited countries.

In recent years, the translation of genomic discoveries into mainstream medical practice and public health has gained momentum, facilitated by the advent of new technologies. However, there are often major discrepancies in the pace of implementation of genomic medicine between developed and developing/resource-limited countries. The main reason does not only lie in the limitation of resources but also in the slow pace of adoption of the new findings and the poor understanding of the potential that this new discipline offers to rationalize medical diagnosis and treatment. Here, we present and critically discuss examples from the successful implementation of genomic medicine in resource-limited countries, focusing on pharmacogenomics, genome informatics, and public health genomics, emphasizing in the latter case genomic education, stakeholder analysis, and economics in pharmacogenomics. These examples can be considered as model cases and be readily replicated for the wide implementation of pharmacogenomics and genomic medicine in other resource-limited environments.

Can the CEIBA Cocktail Designed for Human Cytochrome P450 Enzymes be Used in the Rat for Drug Interaction Studies?

Purpose - The CEIBA cocktail consisting of caffeine (CAF), omeprazole (OZ), dextromethorphan (DM) and losartan (LOS) was previously proposed for the clinical phenotyping of five major human cytochrome P450 (CYP) isoenzymes. This work aimed to assess the usefulness of CEIBA cocktail to study non-clinical drug interactions in the rat. Methods - Wistar rats were divided into five groups to receive a single-oral dose of each probe drug (CAF, OZ, LOS, DM), individually or in combination as a cocktail. Plasma concentrations of the probe drugs and their metabolites [paraxanthine (1,7-X), 5-hydroxyomeprazole (5-OZ), losartan carboxylic acid (E-3174), dextrorphan (DX) and 3-methoxymorphinan (3-MM)] were determined by LC-MS/MS, and the corresponding pharmacokinetic parameters were estimated by non-compartmental analysis. The AUC0-t and Cmax drug/metabolite ratios (phenotypic metrics) were calculated for each probe drug and compared (probe alone versus cocktail). Results - The primary analysis of the pharmacokinetic data suggested the occurrence of pharmacokinetic-based drug interactions when the probe drugs were concurrently administered; such interactions were documented for CAF, 1,7-X, DX and E-3174. Nevertheless, except for the LOS/E-3174 probe drug-metabolite pair (p<0.05), there was little evidence that the probe drugs interacted metabolically as the metabolic ratios calculated were similar in both approaches. Moreover, no evidence was found for relevant pharmacodynamic interactions. Conclusion - CEIBA cocktail seems to be a useful tool to investigate drug interactions involving CYP isoenzymes in the rat, particularly at the level of CYP1A2, CYP2D1/2 and CYP2D2 isoforms using the CAF/1,7-X, OZ/5-OZ and DM/DX metabolic ratios, respectively. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.

Relevance of the ancestry for the variability of the Drug-Metabolizing Enzymes CYP2C9, CYP2C19 and CYP2D6 polymorphisms in a multiethnic Costa Rican population.

CYP2C9, CYP2C19 and CYP2D6 metabolize around 40% of drugs and their genes vary across populations. The Costa Rican population has a trihybrid ancestry and its key geographic location turns it into a suitable scenario to evaluate interethnic differences across populations. This study aims to describe the diversity of CYP2C9, CYP2C19 and CYP2D6 polymorphisms in Costa Rican populations in the context of their ancestry. A total of 448 healthy individuals were included in the study: Bribri (n= 47), Cabécar (n= 27), Maleku (n= 16), Guaymí (n= 30), Huetar (n= 48), Chorotega (n= 41), Admixed/Mestizos from the Central Valley/Guanacaste (n= 189), and Afro-Caribbeans (n= 50) from Limón. CYP2C9 (alleles *2, *3, *6) and CYP2C19 (*2, *3, *4, *5, *17) genotypes were determined by Real-Time PCR. African, European and Native American ancestry were inferred using 87 ancestry informative markers. The frequency of the decreased activity allele CYP2C9*2 is lower in the self-reported Amerindian groups compared to the admixed population, and the highest frequencies of CYP2C19*2 (null activity) and the CYP2C19*17 (increased activity) were found in the self-reported Afro-Caribbean population. Moreover, a frequency of 0.7 % CYP2C9 gPMs in the Admixed population and a variable frequency of CYP2C19 gUMs (0.0-32.6 %, more prevalent in Afro-Caribbeans) in Costa Rican populations, was found. Finally, the following alleles were positively correlated with genomic African ancestry and negatively correlated with genomic Native American ancestry: CYP2D6*5 (null activity), CYP2D6*17 (decreased activity), CYP2D6*29 (decreased activity) and CYP2C19*17 (increased activity). No correlation for CYP2C9 polymorphisms and genomic ancestry was found. Further studies assessing the CYP2C9 and CYP2C19 sequence in these populations, preferentially by sequencing these genes, are warranted.

The Psychostimulant Khat (Catha edulis) Inhibits CYP2D6 Enzyme Activity in Humans.

The use of khat (Catha edulis) while on medication may alter treatment outcome. In particular, the influence of khat on the metabolic activities of drug-metabolizing enzymes is not known. We performed a comparative 1-way crossover study to evaluate the effect of khat on cytochrome P450 (CYP)2D6 and CYP3A4 enzyme activity. After 1 week of khat abstinence, baseline CYP2D6 and CYP3A4 metabolic activities were determined in 40 Ethiopian male volunteers using 30 mg dextromethorphan (DM) as a probe drug and then repeated after 1 week of daily use of 400 g fresh khat leaves. Urinary concentrations of cathinone and cathine were determined to monitor the subjects' compliance to the study protocol. Genotyping for CYP2D6*3 and CYP2D6*4 was done. Plasma DM, dextrorphan and 3-methoxymorphinan concentrations were quantified. CYP2D6 and CYP3A4 enzyme activities were assessed by comparing plasma log DM/dextrorphan and log DM/methoxymorphinan metabolic ratio (MR) respectively in the presence and absence of khat. Cytochrome 2D6 MR was significantly increased from baseline by concurrent khat use (paired t test, P = 0.003; geometric mean ratio, 1.38; 95% confidence interval [95% CI], 1.12-1.53). Moreover, the inhibition of CYP2D6 activity by khat was more pronounced in CYP2D6*1/*1 compared with CYP2D6*1/*4 genotypes (P = 0.01). A marginal inhibition of CYP3A4 activity in the presence of khat was observed (P = 0.24). The mean percentage increase of CYP2D6 and CYP3A4 MR from baseline by khat use was 46% (95% CI, 20-72) and 31% (95% CI, 8-54), respectively. This is the first report linking khat use with significant inhibition of CYP2D6 metabolic activity in humans.

CYP2D6 variation, behaviour and psychopathology: implications for pharmacogenomics-guided clinical trials.

Individual and population differences in polymorphic cytochrome P450 enzyme function have been known for decades. The biological significance of these differences has now been deciphered with regard to drug metabolism, action and toxicity as well as disposition of endogenous substrates, including neuroactive compounds. While the cytochrome P450 enzymes occur abundantly in the liver, they are expressed in most tissues of the body, albeit in varying amounts, including the brain. The latter location of cytochrome P450s is highly pertinent for susceptibility to neuropsychiatric diseases, not to mention local drug metabolism at the site of psychotropic drug action in the brain. In the current era of personality medicine with companion theranostics (i.e. the fusion of therapeutics with diagnostics), this article underscores that such versatile biological roles of cytochrome P450s offer multiple points of entry for personalized medicine and rational therapeutics. We focus our discussion on CYP2D6, one of the most intensively researched drug and endogenous compound metabolism pathways, with a view to relevance for, and optimization of, pharmacogenomic-guided clinical trials. Working on the premise that CYP2D6 is related to human behaviour and certain personality traits such as serotonin and dopamine system function, we further suggest that the motivation of healthy volunteers to participate in clinical trials may in part be influenced by an under- or over-representation of certain CYP2D6 metabolic groups.

A tribute to josé maría ("chema") cantú.

José María ("Chema") Cantú (1938-2007), born in Mexico, was a pioneering, loved and respected leader in medical and human genetics and bioethics in Latin America. He graduated as a physician in Mexico and then trained in medical and human genetics in France and the United States. He was instrumental in developing a first-rate research, training and genetic services program in medical and human genetics in Guadalajara, in northwestern Mexico. He acted forcefully at national, regional and international levels to promote scientific development through collaboration and education in science and humanities, while he simultaneously strived for justice, peace, love and human rights. He attained some of the highest honors a scientist and humanist could aspire to as well as the recognition of the communities he served. Hundreds of disciples throughout Latin America and the world have been inspired by his vision of a better world through the conjunction of science, respect for humankind, ethics and love.

Ethnic background and CYP2D6 genetic polymorphisms in Costa Ricans.

CYP2D6 differences have already been demonstrated within Latin American populations by the CEIBA.FP Consortium of the Ibero-American Network of Pharmacogenetics (RIBEF, as per the acronym in Spanish). However, within the population of Costa Rica, no research has been conducted until now, even though this population has a trihybrid component ancestry that represents an interesting condition. Thus, the present study was aimed to determine the frequency of Ultra-rapid Metabolizers (UMs) and Poor Metabolizers (PMs) in a Costa Rican population, as well as to determine whether there are differences in the CYP2D6-predicted phenotype frequencies among three Costa Rican groups with different ethnic backgrounds. Additionally, these frequencies of PMs and UMs obtained were compared with Ibero-American populations published data. Finally, we also aimed to describe allele frequencies among different Costa Rican ethnic groups. This research has been undertaken within the framework of the RIBEF CEIBA Consortium studies on Latin American populations. A total of 385 individuals were included in the study: 139 mestizos, 197 Amerindians, and 49 Afro-Caribbeans. CYP2D6 genotypes were determined by XL-PCR and Real-Time PCR. The CYP2D6 variant alleles *2, *3, *4, *5, *6, *10, "17, *29, *35 and *41 were also determined. For the entire Costa Rican population, the frequency of PMs and UMs was 6% and 6.5%, respectively. The percentage of UMs in the mestizo population was higher than in the Amerindian population. CYP2D6 UMs vary from 3.6% to 10.1% and PMs from 1.4% to 10.2% among three Costa Rican groups. The highest frequencies of UMs (10.1%) and PMs (10.2%) were found in the mestizo and Amerindian populations, respectively. In conclusion, the frequencies of UMs and PMs for CYP2D6 varied widely across the mestizo, Amerindian and Afro-Caribbean Costa Rican populations. Future research in this population should be oriented to identify new CYP2D6 variants through sequencing methods, as well as to determine CYP2D6 phenotype, in order to establish the phenotype-genotype relation. Finally, further studies involving genetic markers of ancestry are needed in the Costa Rican population.

Impact of SLC22A1 variants rs622342 and rs72552763 on HbA1c and metformin plasmatic concentration levels in patients with type 2 diabetes mellitus.

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.

Longitudinal assessment of SNPs rs72552763 and rs622342 in SLC22A1 over HbA1c control among Mexican-Mestizo diabetic type 2 patients.

Background: In Mexico, 75% of diabetes mellitus type 2 (DMT2) patients are not in glycaemic control criteria (HbA1c<7%); this entails a significantly variable drug response. Amongst the factors influencing such variability, are genetics, more specifically, single nucleotide polymorphisms (SNPs). Three genes implied in metformin pharmacokinetics are SLC22A1, SLC22A2, and SLC22A3, which are polymorphic. While there have been cross-sectional studies on their SNPs impact over drug response, a longitudinal study would contribute valuable information on their effect over time. Methods: SNPs of SLC22A1 (rs72552763, rs622342, rs12208357, rs2282143, rs594709, rs628031, and rs683369), SLC22A2 (rs316019), and SLC22A3 (rs2076828), were determined through PCR-TR. The clinical records of 69 patients undergoing metformin monotherapy were retrospectively assessed. Metformin is the first line treatment against DMT2. A level of HbA1c <7% (time 0) was considered as an inescapable inclusion criterion. The study's cases were those patients who reported HbA1c ≥ 7% (time1) after time 0 (t0). Kaplan-Meier curves including a Log-Rank test and a Cox multivariate analysis of proportional risks were performed. Aim: Determining clinical, biochemical, and genetic variables which may affect non-control (HbA1c ≥ 7%) survival time spans amongst DMT2 Mexican-Mestizo patients undergoing metformin monotherapy at Hospital Regional de Alta Especialidad de Ixtapaluca (HRAEI) between October 2013 and December 2023. Results: All 69 patients were monitored over a median period of 642 days (273-1,134). A comparison between time 0 and time 1 (t1) revealed differences in weight (p = 0.036), metformin dose mg/kg/day (p = 0.003), plasmatic glucose mg/dL (p = 0.048), and HbA1c (p < 0.001). The median non-control survival rate was different across the 3 genotypes of rs62552763 in SLC22A1 (p = 0.0034) and the dominant genotypic model GAT/GAT vs. GAT/del + del/del (p = 0.009). There were differences between rs622342 genotypes as well (p = 0.041). In GAT/GAT the Cox model found HR = 0.407 (IC95%: 0.202-0.818, p = 0.011) in the univariate analysis and HR = 0.418 (IC95%: 0.204-0.856, p = 0.034) in the multivariate analysis, adjusted by initial metformin dose (mg/kg/day), initial weight (kg), and final metformin dose (mg/kg/day). Genotype A/A of rs622342 in SLC22A1, reported HR = 0.392 (IC95%: 0.169-0.910, p = 0.029) in the multivariate analysis as well. Conclusion: Among DMT2 Mexican-Mestizo patients undergoing metformin monotherapy the minor allele del in rs72552763 and the minor allele C in rs622342 reported a significantly shorter survival median respect to the wild type variant. Patients carrying del in rs72552763 or C in rs622342, both in SLC22A1, will reach non-control in less time with respect to other patients. Therefore these genotypes may constitute a therapeutic response biomarker for this population.

CYP2D6 poor metabolizer status might be associated with better response to risperidone treatment.

The variability in the antipsychotic response is, to some extent, genetically determined. Several studies have attempted to establish a role for genetic variation in genes coding pharmacokinetic and pharmacodynamic targets, but to date, no definite genetic predictive marker has been identified. We aimed to explore the putative role of 19 genetic variants and risperidone clinical improvement in 76 White schizophrenic inpatients, measured as change in Positive and Negative Syndrome Scale (PANSS). CYP2D6 poor metabolism was significantly associated with greater clinical improvement in total PANSS and a trend was also found for MDR1 3435C>T to higher total PANSS scores in 3435T carriers. This study suggests the importance that genetic variability on pharmacokinetic factors may have in risperidone response and gives evidence for the need for further investigation in order to establish the actual predictive value and clinical utility that CYP2D6 genotyping might have in risperidone therapy management.

Interethnic differences in UGT1A4 genetic polymorphisms between Mexican Mestizo and Spanish populations.

UDP-glucuronosyltransferase 1A4 (UGT1A4) is a phase II drug-metabolizing enzyme that catalyzes the glucuronidation of many clinically-important drugs. Interethnic differences in the genetic polymorphism of UGT1A4 have been reported; however, there is no information in Mexican Mestizos (MMs) and Spaniards (SPs). Furthermore, MM is an admixed population with 26 % of Caucasian genes mainly from Spain. Therefore, this study aimed to investigate the potential differences between 318 SPs and 248 MMs healthy individuals regarding UGT1A4*1b, UGT1A4*2 and UGT1A4*3 alleles and to compare the observed frequencies with those previously reported in different populations. The allelic frequencies of the three UGT1A4 polymorphisms showed interethnic differences between MMs and SPs (p < 0.05). The analyzed SNPs variants in this genetic region were not in linkage disequilibrium (LD) for the MM population, suggesting that these mutations have arisen independently in the same genetic background. In contrast, UGT1A4*2 and UGT1A4*3 were in LD in the SP population. Comparison of present data with other in different ethnic groups revealed that the frequencies of UGT1A4*2 and UGT1A4*3 in SP were similar to other Caucasians and higher than in Asians, whereas in MMs were lower than in Caucasians and higher than in Asians only for UGT1A4*2. Present results could be helpful to improve the use of UGT1A4 drug substrates in order to adjust them to the ethnic background of a given population, specifically for Hispanics.

Pharmacogenetic Sex-Specific Effects of Methotrexate Response in Patients with Rheumatoid Arthritis.

Methotrexate (MTX) is a commonly used drug for the treatment of rheumatoid arthritis (RA), but its effectiveness can vary greatly among patients. Pharmacogenetics, the study of how genetic variations can affect drug response, has the potential to improve the personalized treatment of RA by identifying genetic markers that can predict a patient's response to MTX. However, the field of MTX pharmacogenetics is still in its early stages and there is a lack of consistency among studies. This study aimed to identify genetic markers associated with MTX efficacy and toxicity in a large sample of RA patients, and to investigate the role of clinical covariates and sex-specific effects. Our results have identified an association of ITPA rs1127354 and ABCB1 rs1045642 with response to MTX, polymorphisms of FPGS rs1544105, GGH rs1800909, and MTHFR genes with disease remission, GGH rs1800909 and MTHFR rs1801131 polymorphisms with all adverse events, and ADA rs244076 and MTHFR rs1801131 and rs1801133, However, clinical covariates were more important factors to consider when building predictive models. These findings highlight the potential of pharmacogenetics to improve personalized treatment of RA, but also emphasize the need for further research to fully understand the complex mechanisms involved.