The Placental Function Beyond Pregnancy: Insights from Latin America.

Currently, more than 100,000 papers had been published studying the placenta in both physiological and pathological contexts. However, relevant health conditions affecting placental function, mostly found in low-income countries, should be evaluated deeper. This review will raise some - of what we think necessary - points of discussion regarding challenging topics not fully understood, including the paternal versus maternal contribution on placental genes imprinting, placenta-brain communication, and some environmental conditions affecting the placenta. The discussions are parts of an international effort to fulfil some gaps observed in this area, and Latin-American research groups currently evaluate that.

Effect of levetiracetam on the gene expression of placental transporters in a murine model.

OBJECTIVE: Levetiracetam (LEV) is an antiseizure medication prescribed to women during childbearing age. The impact of LEV on placental transporters is poorly understood. This study aimed to assess the effect of LEV exposure on the messenger RNA (mRNA) expression of placental transporters for hormones and nutrients and to correlate their expression with the drug's serum concentration in pregnant mice. METHODS: Studies were conducted on gestational days (GD) 13 and 18, following oral treatment with 100 mg/kg LEV or the vehicle every 24 h after weaning. Serum LEV measurements were performed by High-performance liquid chromatography with a UV detector (HPLC-UV). The weight, height, and width of the fetuses were also analyzed. In addition, the placental expression of transporters xCt, Lat1, Oatp4a1, Fr-α, Rfc, and Snat4 was evaluated through semi-quantitative real-time polymerase chain reaction (qPCR). The Kruskal-Wallis and the Mann-Whitney U tests were used to determine the statistical significance (p < .05). The correlation between serum LEV concentration and placental gene expression was evaluated using the Spearman test. RESULTS: The weight, height, and width were lower in the fetuses exposed to LEV compared with the control group (p < .05). The number of fetuses was lower in the LEV-exposed group than in the control GD 13 group (p < .001). No significant differences were detected in the mRNA expression level at GD 13. At GD 18, the expression of Lat1, Oatp4a1, xCT, and Snat4 was higher in the group treated with LEV compared with the control group (p < .05), whereas the expression of Rfc was lower (p < .05). No correlation was identified between serum LEV concentrations and gene expression levels. SIGNIFICANCE: The repression of the Rfc transcript by LEV at GD 18 suggests that the protein expression would be abolished contributing to the observed intrauterine growth restriction (IUGR). Furthermore, the significant increase in mRNA of xCt, Snat4, Oatp4a1, and Lat1 might be a compensatory mechanism for fetal survival at GD 18.

Vascular Dysfunction in Mother and Offspring During Preeclampsia: Contributions from Latin-American Countries.

Pregnancy is a physiologically stressful condition that generates a series of functional adaptations by the cardiovascular system. The impact of pregnancy on this system persists from conception beyond birth. Recent evidence suggests that vascular changes associated with pregnancy complications, such as preeclampsia, affect the function of the maternal and offspring vascular systems, after delivery and into adult life. Since the vascular system contributes to systemic homeostasis, defective development or function of blood vessels predisposes both mother and infant to future risk for chronic disease. These alterations in later life range from fertility problems to alterations in the central nervous system or immune system, among others. It is important to note that rates of morbi-mortality due to pregnancy complications including preeclampsia, as well as cardiovascular diseases, have a higher incidence in Latin-American countries than in more developed countries. Nonetheless, there is a lack both in the amount and impact of research conducted in Latin America. An impact, although smaller, can be seen when research in vascular disorders related to problems during pregnancy is analyzed. Therefore, in this review, information about preeclampsia and endothelial dysfunction generated from research groups based in Latin-American countries will be highlighted. We relate the need, as present in many other countries in the world, for increased effective regional and international collaboration to generate new data specific to our region on this topic.

Micronuclei and nuclear anomalies in Mexico's indigenous population.

OBJECTIVE: To determine the number of micronuclei and nuclear anomalies in Mexico's indigenous population. MATERIALS AND METHODS: One hundred twenty indigenous individuals were evaluated, including thirty from the ethnicities Cora, Huichol, Tarahumara and Tepehuano. The number of micronuclei (MN) and any nuclear abnormality (NA) in oral mucosa cells, including cells with nuclear buds, binucleated cells, cells with karyolysis, karyorrhetic, condensed chromatin and pyknotic cells were determined for each participant. RESULTS: Tepehuano and Tarahumaras showed the greatest damage to DNA. The Tepehuano group presented the highest number of MN and NA, this being a significant difference (p < 0.05) compared with the rest of the studied groups. This group also presented the highest herbicide exposure (46.7%). In relation to the smoking and drinking habits, these were more frequent in the Tarahumara group (33.3 and 50% respectively). CONCLUSION: The ethnic diversity, habits and customs may influence the DNA nuclear integrity in the Amerindian groups.

Importance of the geographic barriers to promote gene drift and avoid pre- and post-Columbian gene flow in Mexican native groups: Evidence from forensic STR Loci.

OBJECTIVE: To analyze the origin, structure, relationships, and recent admixture in Mexican Native groups based on 15 STRs commonly used in human identification. METHODS: We analyzed 39 Mexican Native population samples using STR databases based on the AmpFlSTR® Identifiler kit (n = 3,135), including Mexican-Mestizos (admixed), European and African populations, as reference. RESULTS: Based upon effective population size (Ne) differences, Native groups were clustered into three regions: i) Center-Southeast groups, characterized by larger Ne, migration rate (Nm), genetic diversity (He), and relative homogeneity principally in the Yucatan Peninsula; ii) Isolated southern groups from Chiapas and Oaxaca, characterized by lower Ne, Nm, and He (i.e. higher isolation and genetic differentiation); iii) North-Northwest groups, which are similar to the previous group but are characterized by generating the widest gene flow barrier in the Pre-Hispanic Mexican territory, and currently by elevated admixture in some northern Native groups. Despite the relative congruence between genetic relationships with cultural, linguistic, geographic criteria, these factors do not explain the present-day population structure of Native groups, excepting in those linguistically related to the Mayan that show higher homogeneity. The Isolation by distance model was demonstrated at long distances (>1,500 km), whereas geographic isolation stands as a determining factor to avoid both non-indigenous admixture and bottleneck processes. CONCLUSIONS: Different dynamics of gene flow and drift were observed among Mexican Native groups, highlighting the geographic barriers (mountains, canyons and jungle regions) as the main factor differentiating Pre-Hispanic populations, and eventually helping to avoid Post-European contact admixture and population bottleneck. Am J Phys Anthropol 160:298-316, 2016. © 2016 Wiley Periodicals, Inc.

Association of the polymorphisms 292 C>T and 1304 G>A in the SLC38A4 gene with hyperglycaemia.

BACKGROUND: The SLC38A4 gene is related to system 'A' activity, which seems to be related to impaired gluconeogenesis. The objective of this study was to determine whether the 292 C>T and 1304 G>A polymorphisms of SLC38A4 gene are associated with hyperglycaemia in humans. METHODS: A total of 227 individuals were enrolled in a case-control study, in which hyperglycaemia was defined by plasma glucose levels ≥95 mg/dL. Genotyping was carried out by using real-time polymerase chain reaction. RESULTS: The frequency of mutant alleles of SLC38A4 gene for single-nucleotide polymorphism (SNP) 1304 G>A was 23.6% and 30.2% for SNP 292 C>T. The frequency of allele T for the SNP 292 C>T in the case and control groups did not show significant differences, whereas the frequency of allele A for the SNP 1304 G>A was significantly higher in the case group than in the control group (p = 0.04). In the logistic regression analysis, the SNP 1304 G>A [odds ratio (OR) 1.78; 95%CI 1.04-3.05, p = 0.03] but not SNP 292 C>T (OR 1.41; 95%CI 0.80-2.47, p = 0.23) showed a significant association with hyperglycaemia. After adjusting by body mass index, waist circumference and triglycerides, the SNP 1304 G>A remained significantly associated with hyperglycaemia (OR 2.13; 95%CI 1.18-3.83, p = 0.03). Pair wise linkage disequilibrium showed correlation (D' > 0.82) between 292 C>T and 1304 G>A SNPs. Haplotype association with hyperglycaemia also showed significant association between both homozygous mutant alleles (A/T) and hyperglycaemia (OR 1.68; 95%CI 1.01-2.79, p = 0.048). CONCLUSIONS: Our results suggest that mutant allele A for SNP 1304 G>A of SLC38A4 gene is associated with hyperglycaemia.

Preeclampsia association of placental nucleotide variations in eNOS, VEGFA, and FLT-1 genes in Latin American pregnant women.

INTRODUCTION: Preeclampsia is a leading cause of maternal and fetal morbidity in low- and middle-income countries, including those in Latin America. Placental vascular alterations are crucial in the pathophysiology of preeclampsia and few studies have evaluated nucleotide variations on genes associated with vascular regulation in the human placenta. This study aimed to evaluate whether placental nucleotide variations on eNOS, VEGFA, and FLT-1 genes are more frequently associated with preeclampsia in the Latin American population. METHODS: This case-control study included placental tissue from 88 controls and 82 cases that were genotyped through Taqman probes for eNOS, VEGFA, and FLT-1 genes. The intergroup comparisons were analyzed with the Mann-Whitney U test. Genotype and allele frequencies were compared by the X2 test. The association between the nucleotide variants with preeclampsia was evaluated through logistic regression analysis. RESULTS: A significant association was observed for VEGFA SNV rs2010963 (OR 1.95; CI 95% 1.13-3.37), after adjusting for population substructure. The allele combination T, G, G, C, C, C (rs2070744, rs1799983, rs2010963, rs3025039, rs699947 and rs4769613 respectively), showed a negative association with preeclampsia (OR 0.08; CI 95% 0.01-0.93). DISCUSSION: Placental SNV rs2010963 in the VEGFA gene was a risk factor for preeclampsia, while the allele combination T, G, G, C, C, C may represent potential protective factors for preeclampsia within Latin American women.

Pharmacogenetics: ethnicity, treatment and health in Latin American populations.

The Ibero-American Network of Pharmacogenetics and Pharmacogenomics (RIBEF) studies Latin American populations to benefit from the implementation of personalized medicine. Since 2006, it has studied ethnicity to apply pharmacogenetics knowledge in autochthonous populations of Latin America, considering ancestral medicine. The meeting 'Pharmacogenetics: ethnicity, Treatment and Health in Latin American Populations' was held in Mexico City, Mexico, and presented the relevance of RIBEF collaboration with Latin American researchers and the governments of Mexico, Spain and the Autonomous Community of Extremadura. The results of 17 years of uninterrupted work by RIBEF, the Declaration of Mérida/T'Hó and the call for the Dr José María Cantú Award for studies focused on the pharmacogenetics of native populations in Latin America were presented.

Biochemical differences in ethnic groups in Durango, Mexico.

OBJECTIVE: The aim of this study was to assess biochemical differences between Tepehuano indigenous people, and Mennonite and Mestizo populations of Durango, Mexico. METHODS: Our study involved 334 volunteers aged 15 to 80 years; 132 Mennonite and 130 Mestizo individuals from Nuevo Ideal Municipality and 72 Tepehuano indigenous people from Mezquital Durango were evaluated. A clinical history and fast determination of aspartate aminotransferase (AST), alanine aminotransferase (ALT), uric acid, urea and creatinine were performed on each studied case. RESULTS: Statistically significant differences between the three studied groups were found for age, weight and height (P < .05), with higher values observed in men. The highest plasma urea levels were found in Mennonite compared to Mestizo people, followed by the Tepehuano indigenous. Higher biochemical parameters were found in men (vs women) in the studied groups. The percentage of individuals with abnormal levels for AST, ALT and uric acid were higher in Tepehuano indigenous people than in Mestizo, whereas the urea and creatinine percentages were higher in Mestizo people. CONCLUSION: The differences found on biochemical tests, could be explained by differences in lifestyle such as diet and sanitary habits.

Evaluation of the PLAC8 Gene in Mexican Women With and Without Preeclampsia and Obesity.

Preeclampsia (PE) is a leading cause of maternal-fetal mortality worldwide, and obesity is an important risk factor. Genes associated with pathophysiological events common to preeclampsia and obesity, such as PLAC8, remain to be studied; therefore, the aim of the present study was to evaluate this gene in the placentas of women affected with preeclampsia and healthy pregnant women. This case-controlled study included 71 healthy and 64 preeclampsia pregnancies. Gene expression was evaluated in primary human cytotrophoblasts (PHCT) from six normal and six preeclampsia pregnancies, and protein expression was verified in placentas from five healthy and six preeclampsia pregnancies. The whole coding and 5' regions of the PLAC8 gene were sequenced from healthy (n = 10) and preeclamptic (n = 10) pregnancies. The presence of the observed nucleotide variations was analyzed by RT-PCR in the total population. Statistical analyses were performed accordingly. Obesity was associated with severe preeclampsia (SPE) (OR = 3.34; CI 95% 1.3-8.2, p < 0.01). Significantly higher mRNA and protein expression was observed in preeclamptic vs. healthy placentas (p < 0.05). After sequencing, a single nucleotide variation was identified in 10 cases and one control (p < 0.01), which was then evaluated in the total population showing no association with preeclampsia. This preliminary study confirms the association of SPE with obesity and suggests higher expression of PLAC8 mRNA and protein in placentas from preeclampsia. No differences in nucleotide variations between cases and controls of the whole population were observed. Further research is required to evaluate the implications of higher gene/protein expression in preeclampsia and the causes of such variation.

Population genetics of PDE4B (phosphodiesterase-4B) in neglected Native Americans: Implications for cancer pharmacogenetics.

PDE4B (phosphodiesterase-4B) has an important role in cancer and in pharmacology of some disorders, such as inflammatory diseases. Remarkably in Native Americans, PDE4B variants are associated with acute lymphoblastic leukemia (ALL) relapse, as this gene modulates sensitivity of glucocorticoids used in ALL chemotherapy. PDE4B allele rs6683977.G, associated with genomic regions of Native American origin in US-Hispanics (admixed among Native Americans, Europeans, and Africans), increases ALL relapse risk, contributing to an association between Native American ancestry and ALL relapse that disappeared with an extra-phase of chemotherapy. This result insinuates that indigenous populations along the Americas may have high frequencies of rs6683977.G, but this has never been corroborated. We studied ancestry and PDE4B diversity in 951 healthy individuals from nine Latin American populations. In non-admixed Native American populations rs6683977.G has frequencies greater than 90%, is in linkage disequilibrium with other ALL relapse associated and regulatory variants in PDE4B-intron-7, conforming haplotypes showing their highest worldwide frequencies in Native Americans (>0.82). Our findings inform the discussion on the pertinence of an extra-phase of chemotherapy in Native American populations, and exemplifies how knowledge generated in US-Hispanics is relevant for their even more neglected and vulnerable Native American ancestors along the American continent.

Unraveling Signatures of Local Adaptation among Indigenous Groups from Mexico.

Few studies have addressed how selective pressures have shaped the genetic structure of the current Native American populations, and they have mostly limited their inferences to admixed Latin American populations. Here, we searched for local adaptation signals, based on integrated haplotype scores and population branch statistics, in 325 Mexican Indigenous individuals with at least 99% Native American ancestry from five previously defined geographical regions. Although each region exhibited its own local adaptation profile, only PPARG and AJAP1, both negative regulators of the Wnt/ß catenin signaling pathway, showed significant adaptation signals in all the tested regions. Several signals were found, mainly in the genes related to the metabolic processes and immune response. A pathway enrichment analysis revealed the overrepresentation of selected genes related to several biological phenotypes/conditions, such as the immune response and metabolic pathways, in agreement with previous studies, suggesting that immunological and metabolic pressures are major drivers of human adaptation. Genes related to the gut microbiome measurements were overrepresented in all the regions, highlighting the importance of studying how humans have coevolved with the microbial communities that colonize them. Our results provide a further explanation of the human evolutionary history in response to environmental pressures in this region.

Methylphenidate lacks genotoxic effects in mouse peripheral blood erythrocytes.

Methylphenidate (MPH; Ritalin®; Novartis Pharmaceuticals, Inc., Basel, Switzerland) has been prescribed to treat attention deficit/hyperactivity disorder (ADHD) since its approval by the U.S. Food and Drug Administration over 50 years ago. Due to concerns that MPH might induce cytogenetic alterations in children, treatment with this drug has been a controversial issue. In the present study, we assessed the frequency of micronucleated erythrocytes (MNEs), micronucleated polychromatic erythrocytes (MNPCEs), and polychromatic erythrocytes (PCEs) in peripheral blood samples from mice treated with three different doses of MPH (30, 60, or 125 mg/kg). We found no evidence of increased MNEs or MNPCEs, nor did PCEs decline. These results add to the accumulating evidence that MPH does not induce genotoxic or cytotoxic damage.

Placental SLC38A4 gene polymorphisms 1304 G > A and 292 C > T, and their association with glucose > 95 mg/dl in normal weight full-term healthy newborns.

BACKGROUND: The SLC38A4 gene encodes for the SNAT4 protein, which has been related to glucose metabolic alterations in human newborns. This study aimed to determine whether the 1304 G > A and 292 C > T polymorphisms of the SLC38A4 gene are associated with the presence of glucose levels > 95 mg/dL in normal weight full-term healthy newborns. METHODS: We conducted a case-control study and analyzed 50 normal weight full-term healthy newborns. Groups were defined based on glucose levels: > 95 mg/dL (cases; n = 13) and < 95 mg/dL (controls; n = 37). The 1304 G > A and 292 C > T polymorphisms of the SLC38A4 gene were determined through quantitative polymerase chain reaction using placental DNA. The association between polymorphism and glucose levels > 95 mg/dL was established using multivariate logistic regression analysis. RESULTS: No significant differences were observed either for gestational age or body weight at birth between groups. In the case group, newborns showed significantly higher homeostatic model assessment for insulin resistance than those in the control group (p < 0.0005). The odds ratio (OR) between the SLC38A4 gene 292 C > T single-nucleotide polymorphism (SNP) and glucose levels > 95 mg/dL was 7.78 (p = 0.024), whereas no significant association was found for the 1304 G > A SNP (OR 1.46; p = 0.77). CONCLUSIONS: Our results suggest that the SLC38A4 gene 292 C > T SNP is associated with glucose levels > 95 mg/dL in normal weight full-term healthy newborns.

Syncytiotrophoblast stress in early onset preeclampsia: The issues perpetuating the syndrome.

Preeclampsia is a pregnancy-specific syndrome characterized by a sudden increase in blood pressure accompanied by proteinuria and/or maternal multi-system damage associated to poor fetal outcome. In early-onset preeclampsia, utero-placental perfusion is altered, causing constant and progressive damage to the syncytiotrophoblast, generating syncytiotrophoblast stress. The latter leads to the detachment and release of syncytiotrophoblast fragments, anti-angiogenic factors and pro-inflammatory molecules into maternal circulation, resulting in the emergence and persistence of the characteristic symptoms of this syndrome during pregnancy. Therefore, understanding the origin and consequences of syncytiotrophoblast stress in preeclampsia is vital to develop new therapeutic alternatives, focused on reducing the burden of this syndrome. In this review, we describe five central characteristics of syncytial stress that should be targeted or prevented in order to reduce preeclampsia symptoms: histological alterations, syncytiotrophoblast damage, antiangiogenic protein export, placental deportation, and altered syncytiotrophoblast turnover. Therapeutic management of these characteristics may improve maternal and fetal outcomes.

The genomic landscape of Mexican Indigenous populations brings insights into the peopling of the Americas.

The genetic makeup of Indigenous populations inhabiting Mexico has been strongly influenced by geography and demographic history. Here, we perform a genome-wide analysis of 716 newly genotyped individuals from 60 of the 68 recognized ethnic groups in Mexico. We show that the genetic structure of these populations is strongly influenced by geography, and our demographic reconstructions suggest a decline in the population size of all tested populations in the last 15-30 generations. We find evidence that Aridoamerican and Mesoamerican populations diverged roughly 4-9.9 ka, around the time when sedentary farming started in Mesoamerica. Comparisons with ancient genomes indicate that the Upward Sun River 1 (USR1) individual is an outgroup to Mexican/South American Indigenous populations, whereas Anzick-1 was more closely related to Mesoamerican/South American populations than to those from Aridoamerica, showing an even more complex history of divergence than recognized so far.

Influence of CYP2D6 deletion, multiplication, -1584C-->G, 31G-->A and 2988G-->a gene polymorphisms on dextromethorphan metabolism among Mexican tepehuanos and mestizos.

The aim of this study was to explain the variability of CYP2D6 activity by the identification of CYP2D6 deletion and multiplications, and the single-nucleotide polymorphisms (SNPs) -1584C-->G, 31G-->A and 2988G-->A in Mexican Mestizo and Tepehuano subjects. One hundred twelve Mestizos and 99 Tepehuano Amerindians were studied, who were previously phenotyped with dextromethorphan. The frequencies of CYP2D6*2A [-1584C-->G] and *35 [-1584C-->G, 31G-->A] were 10.7 and 4.1%, respectively, in Mestizos, which is evidently a trend towards an extensive metabolism in carriers of the -1584G change. In Tepehuanos, *2A was identified with a frequency of 20%, and the allele *35 was not found. The frequencies of CYP2D6*5 (deletion) and *41[2988G-->A] were 1.3 and 2.2% in Mestizos and 0.5 and 1% in Tepehuanos, respectively. The SNP 2988A was found to be significantly related with the intermediate metabolizer phenotype in Mestizos (R = 0.309; n = 88; p = 0.006). The multiplications had frequencies of 4.1% in Mestizos and 1.5% in Tepehuanos. Only in the Mestizos did the presence of multiplications significantly decrease the DM/DX (dextromethorphan/dextrorphan) values (R = 0.273; n = 88; p = 0.016). The polymorphisms studied had different frequencies between Tepehuanos and Mestizos (p < 0.001); however, in the Tepehuano group these had a low influence on their phenotypic expression. It helps to understand the genotype-phenotype relationships of CYP2D6 in our studied populations.

The role of xenobiotic-metabolizing enzymes in the placenta: a growing research field.

Introduction: The placenta is a temporary and unique organ that allows for the physical connection between a mother and fetus; this organ regulates the transport of gases and nutrients mediating the elimination of waste products contained in the fetal circulation. The placenta performs metabolic and excretion functions, on the basis of multiple enzymatic systems responsible for the oxidation, reduction, hydrolysis, and conjugation of xenobiotics. These mechanisms give the placenta a protective role that limits the fetal exposure to harmful compounds. During pregnancy, some diseases require uninterrupted treatment even if it is detrimental to the fetus. Drugs and other xenobiotics alter gene expression in the placenta with repercussions for the fetus and mother's well-being.Areas covered: This review provides a brief description of the human placental structure and function, the main drug and xenobiotic transporters and metabolizing enzymes, placenta-metabolized substrates, and alterations in gene expression that the exposure to xenobiotics may cause.Expert opinion: Research should be focused on the identification and validation of biological markers for the assessment of the harmful effects of some drugs in pregnancy, including the evaluation of polymorphisms and methylation patterns in chorionic villous samples and/or amniotic fluid.

The CYP2C19*2 and CYP2C19*17 Polymorphisms Influence Responses to Clozapine for the Treatment of Schizophrenia.

INTRODUCTION: Clozapine (CLZ) is the gold standard drug for treatment-refractory schizophrenia (TRS). However, approximately 30% of patients partially respond to CLZ, defining this subset with super refractory schizophrenia (SRS). Alterations in enzyme activity may affect CLZ responses; the CYP3A4, CYP1A2 and CYP2C19 genes are primarily responsible for CLZ metabolism. OBJECTIVE: The aim of this study was to assess if CYP2C19 variants were associated with TRS or SRS. METHODS: CYP2C19*2 loss-of-function and CYP2C19*17 gain-of-function polymorphism genotype testing were performed in 108 individuals undergoing pharmacological treatment for TRS or SRS. DNA was extracted and polymorphisms were analyzed by polymerase chain reaction (PCR) and sequencing. RESULTS: CYP2C19*17 had positive correlations with SRS and lower Brief Psychiatric Rating Scale (BPRS) scores for TRS. In addition, CYP2C19*2 was associated with lower CLZ dosages for TRS. CONCLUSION: These results show that CYP2C19*2 and CYP2C19*17 polymorphisms influence CLZ responses during schizophrenia treatment.

Influence of Genetic Admixture Components on CYP3A5*3 Allele-Associated Hypertension in Amerindian Populations From Northwest Mexico.

CYP3A5 metabolizes endogenous substrates and ~30% of prescription drugs. The CYP3A5 gene contains an active CYP3A5*1 allele, and a non-functional version, the CYP3A5*3 (rs776746), with consequences for drug therapeutic responses and side effects. Both CYP3A5*1 and *3 have been associated with hypertension. The frequency of CYP3A5*3 varies between populations of different ancestries, with Europeans having the highest allele frequency (> 90%). Given the importance of CYP3A5*3 in drug response and hypertension development, the aim of the present study was to evaluate the frequency of this polymorphism and its association with hypertension in vulnerable indigenous populations in Mexico. A total of 372 subjects were recruited from eight ethnic groups in Northwest Mexico. Systolic (SBP), diastolic (DBP), and median (MBP) blood pressures as well as body mass index (BMI) were measured. Ancestry was evaluated through STR analysis, and the CYP3A5*1/*3 polymorphisms were identified using real-time PCR with TaqMan® probes. Higher frequencies of CYP3A5*1 and *3 were observed in groups with higher (>90%) and lower (<90%) Amerindian ancestry, respectively. The CYP3A5*3/*3 genotype was more frequent in indigenous women with higher SBP and DBP values. On the other hand, the *1 allele showed a protective effect against both high SBP (OR, 0.38; 95% CI, 0.17-0.83, p = 0.001) and DBP (OR 0.38, 95% CI 0.18-0.81, p = 0.007) in women. This association remained significant after adjusting for BMI and age for diastolic (OR, 0.38; 95% CI, 0.17-0.84, p = 0.011) and systolic BP (OR, 0.33; 95% CI, 0.15-0.76, p = 0.005) BP levels in women. Thus, the frequency of CYP3A5*3 varies between groups and seems to depend on ancestry, and CYP3A5*1 decreases the risk of hypertension in Mexican indigenous women. This population analysis of CYP3A5*1/*3 has profound implications not only for the susceptibility to diseases, such as hypertension, but also for safer drug administration regimens, assuring better therapeutic responses and fewer side effects.