Search

Background Nonalcoholic fatty liver disease (NAFLD) is a leading cause of chronic liver disease and cirrhosis. NAFLD is mediated by changes in lipid metabolism and known risk factors include obesity, metabolic syndrome, and diabetes. The aim of this study was to better understand differences in the lipid composition of individuals with NAFLD compared to controls, by performing direct infusion lipidomics on serum biospecimens from a cohort study of adults in Mexico. Methods A nested case-control study was conducted with a sample of 98 NAFLD cases and 100 healthy controls who are participating in an on-going, longitudinal study in Mexico. NAFLD cases were clinically confirmed using elevated liver enzyme tests and liver ultrasound or liver ultrasound elastography, after excluding alcohol abuse, and 100 controls were identified as having at least two consecutive normal alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ( Results NAFLD cases had differences in total amounts of serum cholesterol esters, lysophosphatidylcholines, sphingomyelins, and triacylglycerols (TAGs), however, other lipid subclasses were similar to controls. Analysis of individual TAG species revealed increased incorporation of saturated fatty acyl tails in serum of NAFLD cases. After adjusting for age, sex, body mass index, and PNPLA3 genotype, a combined panel of ten lipids predicted case or control status better than an area under the ROC curve of 0.83. Conclusions These preliminary results indicate that the serum lipidome differs in patients with NAFLD, compared to healthy controls, and suggest that assessing the desaturation state of TAGs or a specific lipid panel may be useful clinical tools for the diagnosis of NAFLD.

Vitamin D deficiency (VDD) and polymorphisms in the group-specific component (GC) gene are known to be associated in different populations. However, the effects of such genetic variants may vary across different populations. Thus, the objective of this study was to estimate the association between Vitamin D-Binding Protein (VDBP) haplotypes and VDD in mestizo postmenopausal women and Mexican Amerindian ethnic groups. This was a cross-sectional study of 726 postmenopausal Mexican women from the Health Workers Cohort Study (HWCS) and 166 postmenopausal women from the Metabolic Analysis in an Indigenous Sample (MAIS) cohort in Mexico. GC polymorphisms (rs7045 and rs4588) were analyzed by TaqMan probes. Serum 25-hydroxyvitamin D [25(OH)D] levels were measured by Chemiluminescent Microparticle Immuno Assay. The prevalence of VDD serum 25(OH)D

Type I interferon (IFN-I) pathway plays a central role in the systemic lupus erythematosus (SLE) pathogenesis. Recent data suggest that SLE is associated with variants in IFN-I genes, such as tyrosine kinase 2 (TYK2), which is crucial in anti-viral immunity. Here, five TYK2 single nucleotide polymorphisms (SNPs) were genotyped in 368 childhood-onset SLE Mexican patients and 516 sex-matched healthy controls. Allele frequencies were also estimated in four indigenous groups. SLE protection was associated with TYK2 risk infection variants affecting residually its catalytic domain, rs12720356 (OR = 0.308; p = 0.041) and rs34536443 (OR = 0.370; p = 0.034), but not with rs2304256, rs12720270, and rs280500. This association was replicated in a 506 adult-onset SLE patients sample (OR = 0.250; p = 0.005, and OR = 0.277; p = 0.008, respectively). The minor alleles of both associated SNPs had a lower frequency in Mestizos than in Spaniards and were absent or rare in indigenous, suggesting that the presence of these alleles in the Mexican Mestizo population was derived from the Spaniards. For the first time, we report genetic variants with a protective effect in childhood- and adult-onset SLE Mexican population. Our results suggest that the frequency of IFN-I alleles associated with SLE, may have been shaped in populations exposed to infectious diseases for long periods, and this could be an explanation why Native American ancestry is associated with a higher SLE prevalence and an earlier onset.

Objective: The aim of this study was to analyze the genetic association of five ESR1 single nucleotide polymorphisms (SNPs) (rs3020331, rs851982, rs1999805, rs2234693, rs3020404), four COL1...

Pulmonary hypertension is a rare condition that impairs patients’ quality of life and life expectancy. The development of noninvasive instruments may help elucidate the prognosis of this cardiorespiratory disease. We aimed to evaluate the utility of routinely performed noninvasive test results as prognostic markers in patients with pulmonary hypertension. We enrolled 198 patients with mean pulmonary artery pressure &gt, 25 mmHg measured at cardiac catheterisation or echocardiographic pulmonary artery systolic pressure &gt, 40 mmHg and tricuspid regurgitation Vmax &gt, 2.9 m/s, and clinical information regarding management and follow-up studies from the date of diagnosis. Multivariate analysis revealed that female sex [HR: 0.21, (95% CI: 0.07–0.64), p = 0.006], the presence of collagenopathies [HR: 8.63, (95% CI: 2.38–31.32), p = 0.001], an increased red blood cell distribution width [HR: 1.25, (95% CI: 1.04–1.49), p = 0.017] and an increased electrocardiographic P axis (P°)/T axis (T°) ratio [HR: 0.93, (95% CI: 0.88–0.98), p = 0.009] were severity-associated factors, while older age [HR: 1.57, (95% CI: 1.04–1.28), p = 0.006], an increased QRS axis (QRS°)/T° ratio [HR: 1.21, (95% CI: 1.09–1.34), p &lt, 0.001], forced expiratory volume in 1 s [HR: 0.94, (95% CI: 0.91–0.98), p = 0.01] and haematocrit [HR: 0.93, (95% CI: 0.87–0.99), p = 0.04] were mortality-associated factors. Our results support the importance of red blood cell distribution width, electrocardiographic ratios and collagenopathies for assessing pulmonary hypertension prognosis.

Background Macro- and micronutrients, such as proteins, vitamin D, and calcium (Ca), are important dietary factors that can modify bone mineral density (BMD). Genetic factors can interact with diet, affecting an individual's predisposition to osteoporosis. Objectives This study aimed to evaluate the associations between macro- and micronutrient intakes and BMD in Mexican postmenopausal women, and their interactions with genetic polymorphisms involved in the vitamin D metabolic pathway. Methods We analyzed data from 317 postmenopausal women from the Health Workers Cohort Study, a longitudinal cohort studied in Cuernavaca, Mexico. Postmenopausal women participated in 2 data collection waves (2004-2006 and 2010-2011), with a mean time of 6.4 years. Dietary intake was assessed with a semi-quantitative FFQ. BMD (femoral neck, hip, and lumbar spine) was measured by DXA. Hybrid mixed-effects regression models were used to assess the associations of dietary macro- and micronutrients on BMD, after adjusting for confounding factors and for diet and single nucleotide polymorphism interactions. Results At baseline, the median age was 57 years (IQR, 50-64). Mean femoral neck, hip, and lumbar spine BMDs decreased over time. We observed statistically significant longitudinal associations for diet (Ca, vitamin D, magnesium, phosphorus, and protein intake) and BMD. Increases of vitamin D, Ca, and protein intakes by 1 SD were associated with mean increases in the femoral neck BMD (0.083 SD, 0.064 SD, and 0.130 SD, respectively). Multiple significant interactions were identified between several loci (CYP2R1, CYP24A1, CYP27B1, VDR, and DHCR7/NADSYN1) and diet for BMDs (femoral neck, hip, and lumbar spine), mainly for protein intake. Conclusions Our data support associations of vitamin D, Ca, protein, phosphorous, and magnesium consumption with BMD in Mexican postmenopausal women and suggest possible gene-diet interactions. These results could facilitate future personalized nutrition recommendations to help prevent low BMD.

Background: Estimates of the burden of cardio-metabolic risk factors in Latin America and the Caribbean (LAC) rely on relative risks (RRs) from non-LAC countries. Whether these RRs apply to LAC remains unknown. Methods: We pooled LAC cohorts. We estimated RRs per unit of exposure to body mass index (BMI), systolic blood pressure (SBP), fasting plasma glucose (FPG), total cholesterol (TC) and non-HDL cholesterol on fatal (31 cohorts, n=168,287) and non-fatal (13 cohorts, n=27,554) cardiovascular diseases, adjusting for regression dilution bias. We used these RRs and national data on mean risk factor levels to estimate the number of cardiovascular deaths attributable to non-optimal levels of each risk factor. Results: Our RRs for SBP, FPG and TC were like those observed in cohorts conducted in high-income countries; however, for BMI, our RRs were consistently smaller in people below 75 years of age. Across risk factors, we observed smaller RRs among older ages. Non-optimal SBP was responsible for the largest number of attributable cardiovascular deaths ranging from 38 per 100,000 women and 54 men in Peru, to 261 (Dominica, women) and 282 (Guyana, men). For non-HDL cholesterol, the lowest attributable rate was for women in Peru (21) and men in Guatemala (25), and the largest in men (158) and women (142) from Guyana. Interpretation: RRs for BMI from studies conducted in high-income countries may overestimate disease burden metrics in LAC; conversely, RRs for SBP, FPG and TC from LAC cohorts are similar to those estimated from cohorts in high-income countries. Funding: Wellcome Trust (214185/Z/18/Z)

We evaluated the association between leisure-time physical activity (LTPA), bone mineral content (BMC), and lean mass (LM) in whole body (wb) and limbs of the Mexican adult population. Our results demonstrate that some types of LTPA with relatively high/medium impact on bones such as football, basketball, tennis, and weightlifting improve BMC and LM. To evaluate the effect of different kinds of leisure-time physical activity (LTPA) on bone mass values and its association with lean mass (LM) in the whole body (wb) and limbs of a large sample of Mexican men and premenopausal (pre-MP) women. We conducted a cross-sectional analysis of data from the Health Workers Cohort Study. Bone mineral content (BMC, kg), bone area (cm2), and LM (kg) were measured with DXA. The LTPA level and the “sedentary” condition were determined using a validated questionnaire adapted for the Mexican population. One-way ANOVA tests evaluated the differences in weight, height, body mass index, and wb, lower limb (ll) and upper limb (ul) BMC and LM between the active (those who engaged in LTPA) and sedentary group. Relationships between BMC and LM values were analyzed. Slopes of the curves and Z scores of LTPA groups with respect to the sedentary group were compared. In men, both wb-BMC and ll-BMC were significantly higher in the groups performing basketball, football, tennis, weightlifting, and running, and all wb-LM, ll-LM, and ul-LM were higher in running, weightlifting, football, and basketball groups with respect to the sedentary group. Both the Z scores and the slopes of BMC-vs-LM relationships were higher than the controls, but only in the ll of male basketball and football players. Our findings demonstrate that some types of LTPA with relatively high/medium impact on bones, such as football, basketball, tennis, and weightlifting, improve both BMC and LM compared to sedentary individuals. Finally, this relationship is stronger for the bones found in the legs and it seems that women are less sensitive to this effect, possibly due to hormonal, dietary, and pharmacological reasons.

Introduction Urine self-sampling for human papillomavirus (HPV)-based cervical cancer screening is a non-invasive method that offers several logistical advantages and high acceptability, reducing barriers related to low screening coverage. This study developed and evaluated the performance of a low-cost urine self-sampling method for HPV-testing and explored the acceptability and feasibility of potential implementation of this alternative in routine screening. Methods A series of sequential laboratory assays examined the impact of several pre-analytical conditions for obtaining DNA from urine and subsequent HPV detection. Initially, we assessed the effect of ethylaminediaminetetraacetic acid (EDTA) as a DNA preservative examining several variables including EDTA concentration, specimen storage temperature, time between urine collection and DNA extraction, and first-morning micturition versus convenience sample collection. We further evaluated the agreement of HPV-testing between urine and clinician-collected cervical samples among 95 women. Finally, we explored the costs of self-sampling supplies as well as the acceptability and feasibility of urine self-sampling among women and healthcare workers. Results Our results revealed higher DNA concentrations were obtained when using a 40mM EDTA solution, storing specimens at 25°C and extracting DNA within 72 hrs. of urine collection, regardless of using first-morning micturition or a convenience sampling. We observed good agreement (Kappa = 0.72) between urine and clinician-collected cervical samples for HPV detection. Furthermore, urine self-sampling was an affordable method (USD 1.10), well accepted among cervical cancer screening users, healthcare workers, and decision-makers. Conclusion These results suggest urine self-sampling is feasible and appropriate alternative for HPV-testing in HPV-based screening programs in lower-resource contexts.

The Mexican population has one of the highest prevalences of metabolic syndrome (MetS) worldwide. The aim of this study was to investigate the association of single-nucleotide polymorphisms (SNPs) with MetS and its components. First, we performed a pilot Genome-wide association study (GWAS) scan on a sub-sample derived from the Health Workers Cohort Study (HWCS) (n = 411). Based on GWAS results, we selected the rs1784042 and rs17120425 SNPs in the SIDT1 transmembrane family member 2 (SIDT2) gene for replication in the entire cohort (n = 1963), using predesigned TaqMan assays. We observed a prevalence of MetS in the HWCS of 52.6%. The minor allele frequency for the variant rs17120425 was 10% and 29% for the rs1784042. The SNP rs1784042 showed an overall association with MetS (OR = 0.82, p = 0.01) and with low levels of high-density lipoprotein (HDL-c) (odds ratio (OR) = 0.77, p = 0.001). The SNP rs17120425 had a significant association with type 2 diabetes (T2D) risk in the overall population (OR = 1.39, p = 0.033). Our results suggest an association of the rs1784042 and rs17120425 variants with MetS, through different mechanisms in the Mexican population. Further studies in larger samples and other populations are required to validate these findings and the relevance of these SNPs in MetS.

BackgroundThe elevated consumption of sugar-sweetened beverages (SSBs) in Mexico is an important public health concern. However, the association between SSB consumption and hyperuricemia has been scarcely studied and not well documented.ObjectivesTo prospectively evaluate the association between SSB consumption and risk of hyperuricemia in Mexican adults.MethodsA longitudinal analysis was conducted using data from the Health Workers Cohort Study. Participants were followed from 2004 to 2018, with measurements every 6 y. The analysis sample consisted of 1300 adults, aged 18 to 85 y. SSB consumption during the previous year was evaluated through a semiquantitative FFQ. Hyperuricemia was defined as a concentration of uric acid ≥7.0 mg/dL in men and ≥5.7 mg/dL in women. We evaluated the association of interest using 2 methodologies: fixed-effects logistic regression and generalized estimating equations (GEEs). Potential confounders were included in both approaches.ResultsAt baseline, median intake of SSBs was 472.1 mL/wk (IQR: 198.8-1416.4 mL/wk), and 233 participants had hyperuricemia. Uric acid was higher in participants with an SSB intake ≥7 servings/wk, compared with those with an intake

This study aimed to investigate the association of seven single nucleotide polymorphisms (SNPs) on the RMND1, CCDC170, and ESR1 genes with osteoporosis or hip fracture in a postmenopausal Mexican population.We included a group of 400 postmenopausal women from the Health Workers Cohort Study from the Mexican Institute of Social Security. As a replication sample, we recruited 423 postmenopausal women from the National Institute of Rehabilitation. Demographic data were collected through a structured questionnaire. Bone mineral density was assessed using dual X-ray absorptiometry. Individuals were classified as normal, osteopenia, osteoporosis, and fracture, according to World Health Organization criteria. Genotyping was performed using predesigned TaqMan Probes. Linear regression analysis was used to investigate association.All of the analyzed SNPs showed association with at least one of the phenotypes of the study groups. In addition, we observed a region with linkage disequilibrium within the ESR1 gene in all groups.This study shows that an association of the SNPs can exist with osteopenia, osteoporosis, or fragility fracture. Our results agree with data published elsewhere, supporting the potential of these loci for the identification of the population at risk. However, additional studies are required to determine the extent of this association for other geographic regions of Mexico.

Osteosarcoma is the most common malignant bone neoplasia affecting individuals in the second decade of life. The survival rate has not been improved during the last 25 years, in part because of the lack of specific markers. The microRNAs have been identified as important regulators of gene expression, experimental evidence suggests these molecules as key players in cancer development and progression. To identify miRNAs differentially expressed in serum from patients with osteosarcoma compared to healthy donors in Mexican population. Fifteen osteosarcoma patients and fifteen age and sex matched healthy individuals were recruited. Two pools of total RNA extracted from serum per study group were prepared and the miRNA expression profiles were analyzed through TaqMan Low Density Arrays. Validation was carried out through RT-qPCR using individual TaqMan assays for those miRNAs differentially expressed. Fifteen miRNAs were differentially expressed in osteosarcoma patients compared to healthy controls. Overexpression of miR-215-5p and miR-642a-5p was confirmed by validation through RT-qPCR. The expression analysis of miRNAs from serum in osteosarcoma patients revealed differential expression of miR-215-5p and miR-642a-5p. Both microRNAs are potential markers for osteosarcoma diagnosis.

Non-alcoholic fatty liver disease (NAFLD) is the accumulation of extra fat in liver cells not caused by alcohol. Elevated transaminase levels are common indicators of liver disease, including NAFLD. Previously, we demonstrated that PNPLA3 (rs738409), LYPLAL1 (rs12137855), PPP1R3B (rs4240624), and GCKR (rs780094) are associated with elevated transaminase levels in overweight/obese Mexican adults. We investigated the association between 288 SNPs identified in genome-wide association studies and risk of elevated transaminase levels in an admixed Mexican-Mestizo sample of 178 cases of NAFLD and 454 healthy controls. The rs2896019, rs12483959, and rs3810622 SNPs in PNPLA3 and rs1227756 in COL13A1 were associated with elevated alanine aminotransferase (ALT, ≥40 IU/L). A polygenic risk score (PRS) based on six SNPs in the ADIPOQ, COL13A1, PNPLA3, and SAMM50 genes was also associated with elevated ALT. Individuals carrying 9–12 risk alleles had 65.8% and 48.5% higher ALT and aspartate aminotransferase (AST) levels, respectively, than those with 1–4 risk alleles. The PRS showed the greatest risk of elevated ALT levels, with a higher level of significance than the individual variants. Our findings suggest a significant association between variants in COL13A1, ADIPOQ, SAMM50, and PNPLA3, and risk of NAFLD/elevated transaminase levels in Mexican adults with an admixed ancestry. This is the first study to examine high-density single nucleotide screening for genetic variations in a Mexican-Mestizo population. The extent of the effect of these variations on the development and progression of NAFLD in Latino populations requires further analysis.

Osteoporosis (OP) remains a major public health problem worldwide. The most serious complications of this disease are fragility fractures, which increase morbidity and mortality. Management of OP represents an economic burden for health systems. Therefore, it is necessary to develop new screening strategies to identify the population at risk and implement preventive measures. We previously identified the SNPs rs3801387 in WNT16, rs7108738 in SOX6, rs10036727 in SLIT3 and rs7584262 in PKDCC as associated with bone mineral density in postmenopausal women through a genome-wide association study. The aim of this study was to validate those SNPs in two independent cohorts of non-related postmenopausal women. We included 1160 women classifying them as normal, osteopenic or osteoporotic and a group with hip fragility fracture. Genotyping was performed using predesigned TaqMan assays. The variants rs10036727 and rs7108738 showed a significant association with BMD at the femoral neck. SLIT3 has been previously proposed as a potential biomarker and therapeutic resource. Our results provide new evidence regarding a possible involvement of SLIT3 in bone metabolisms and encourage the development of more studies in different populations to support these observations.

Osteoporosis is a skeletal disease mainly affecting women over 50 years old and it represents a serious public health problem because of the high socioeconomic burden. This disease is characterized by deterioration of bone microarchitecture, low bone mineral density (BMD), and increased risk of fragility fractures. This study aimed to identify serum useful proteins as biomarkers for the diagnosis and/or prognosis of osteoporosis and fracture risk. We collected 446 serum samples from postmenopausal women aged &ge, 45 years old. Based on the BMD measurement, we classified the participants into three groups: osteoporotic, osteopenic, and normal. In an initial discovery stage, we conducted a proteomic approach using two-dimensional differential gel electrophoresis (2D-DIGE). The peptides into the spots of interest were identified through matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF/TOF). Enzyme-linked immunosorbent assay (ELISA) was performed to validate the proteins of interest. We identified 27 spots of interest when comparing low BMD versus normal BMD postmenopausal women. Based on their relevance in bone metabolism, we analyzed three proteins: ceruloplasmin (CP), gelsolin (GSN), and vitamin D-binding protein (VDBP). Our results demonstrated that low serum VDBP levels correlate with low BMD (osteopenic and osteoporotic). Therefore, VDBP could be considered as a novel, potential, and non-invasive biomarker for the early detection of osteoporosis.

The present study aims: (1) to explore the influence of lean mass (LM) on bone mineral content (BMC), (2) to investigate the pubertal influences on the BMC–LM relation, and (3) to perform Z-score charts of BMC–LM relation, stratified by gender and reproductive status categorized by age ranges. A cross-sectional analysis was conducted using 4001 healthy subjects between 7 and 90 years participating in the Health Workers Cohort Study. Of these, 720 participants were ≤ 19 years, 2417 were women ≥ 20 years, and 864 were men ≥ 20 years. Using Dual X-ray absorptiometry (DXA), we measured BMC and LM. Participants’ pubertal development was assessed according to Tanner’s stage scale. To describe BMC–LM relation, simple correlation coefficients were computed. To produce best-fit equations, an ANOVA test was conducted. Z-score graphs for the BMC–LM relation were obtained. In general, the BMC–LM correlations were linear and highly significant. For boys, curves were virtually parallel, with similar intercepts and a progressive displacement of values toward the upper-right region of the graph, for each Tanner subgroup. For girls, curves for Tanner 1-2 and 4-5 stages were parallel; but, in girls Tanner 4-5, the intercepts were significantly higher by about +300–400 g of BMC (P < 0.001). For postmenopausal women, the curve was parallel to that for the premenopausal but showed a lower intercept (P < 0.001). We provide DXA reference data on a well-characterized cohort of 4001 healthy subjects. These reference curves provide a reference value for the assessment and monitoring of bone health in all age groups included in the present study. Fil: Denova Gutiérrez, Edgar. Instituto Nacional de Salud Pública; México Fil: Clark, Patricia. Hospital Infantil de México Federico Gómez. Unidad de Investigación en Epidemiología Clínica; México. Universidad Nacional Autónoma de México; México Fil: Capozza, Ricardo Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Médicas. Centro de Estudios de Metabolismo Fosfocálcico; Argentina Fil: Nocciolino, Laura Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Médicas. Centro de Estudios de Metabolismo Fosfocálcico; Argentina Fil: Ferretti, Jose Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Médicas. Centro de Estudios de Metabolismo Fosfocálcico; Argentina Fil: Velázquez Cruz, Rafael. Instituto Nacional de Medicina Genómica México. Laboratorio de Genómica del Metabolismo Óseo; México Fil: Rivera, Berenice. Universidad Nacional Autónoma de México; México Fil: Cointry, Gustavo Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Médicas. Centro de Estudios de Metabolismo Fosfocálcico; Argentina Fil: Salmerón, Jorge. Universidad Nacional Autónoma de México; México. Instituto Nacional de Salud Pública; México

Risk of hyperuricemia is modified by genetic and environmental factors. Our aim was to identify factors associated with serum uric acid levels and hyperuricemia in Mexicans. A pilot Genome-wide association study GWAS was performed in a subgroup of participants (n = 411) from the Health Workers Cohort Study (HWCS). Single nucleotide polymorphisms (SNPs) associated with serum uric acid levels were validated in all the HWCS participants (n = 1939) and replicated in independent children (n = 1080) and adult (n = 1073) case-control studies. The meta-analysis of the whole HWCS and replication samples identified three SLC2A9 SNPs: rs1014290 (p = 2.3 &times, 10&minus, 64), rs3775948 (p = 8.2 &times, 64) and rs11722228 (p = 1.1 &times, 17), and an ABCG2 missense SNP, rs2231142 (p = 1.0 &times, 18). Among the non-genetic factors identified, the visceral adiposity index, smoking, the metabolic syndrome and its components (waist circumference, blood pressure, glucose and hyperlipidemia) were associated with increased serum uric acid levels and hyperuricemia (p &lt, 0.05). Among the female HWCS participants, the odds ratio for hyperuricemia was 1.24 (95% CI, 1.01&ndash, 1.53) per unit increase in soft drink consumption. As reported in other studies, our findings indicate that diet, adiposity and genetic variation contribute to the elevated prevalence of hyperuricemia in Mexico.

Background: Serum uric acid (SUA) is a heritable trait associated with cardiovascular risk factors and coronary artery disease (CAD). Genome wide association studies (GWAS) have identified several genes associated with SUA, mainly in European populations. However, to date there are few GWAS in Latino populations, and the role of SUA-associated single nucleotide polymorphisms (SNPs) in cardiovascular disease has not been studied in the Mexican population. Methods: We performed genome-wide SUA association study in 2153 Mexican children and adults, evaluated whether genetic effects were modified by sex and obesity, and used a Mendelian randomization approach in an independent cohort to study the role of SUA modifying genetic variants in premature CAD. Results: Only two loci were associated with SUA levels: SLC2A9 (β = −0.47 mg/dl, P = 1.57 × 10−42 for lead SNP rs7678287) and ABCG2 (β = 0.23 mg/dl, P = 2.42 × 10−10 for lead SNP rs2231142). No significant interaction between SLC2A9 rs7678287 and ABCG2 rs2231142 genotypes and obesity was observed. However, a significant ABCG2 rs2231142 genotype*sex interaction (P = 0.001) was observed in adults but not in children. Although SUA levels were associated with premature CAD, metabolic syndrome and decreased glomerular filtration rate (eGFR), only ABCG2 rs2231142 was associated with decreased eGFR in the premature CAD group. Conclusions: SUA elevation was independently associated with premature CAD, metabolic syndrome and decreased eGFR in the Mexican population. However, a Mendelian randomization approach using the lead SUA-associated SNPs (SLC2A9 and ABCG2) did not support a causal role of elevated SUA levels for premature CAD. Fil: Macias Kauffer, Luis R.. Instituto Nacional de Medicina Genómica Mexico; México. Universidad Nacional Autónoma de México; México Fil: Villamil Ramírez, Hugo. Instituto Nacional de Medicina Genómica Mexico; México Fil: León Mimila, Paola. Instituto Nacional de Medicina Genómica Mexico; México Fil: Jacobo Albavera, Leonor. Inmegen; México Fil: Posadas Romero, Carlos. Instituto Nacional de Cardiologia Ignacio Chavez; México Fil: Posadas Sánchez, Rosalinda. Instituto Nacional de Cardiologia Ignacio Chavez; México Fil: López Contreras, Blanca E.. Instituto Nacional de Medicina Genómica Mexico; México Fil: Morán Ramos, Sofía. Instituto Nacional de Medicina Genómica Mexico; México Fil: Romero Hidalgo, Sandra. Inmegen; México Fil: Acuña Alonzo, Víctor. Colegio Universitario de Londres; Reino Unido Fil: del Río Navarro, Blanca E.. Hospital Infantil de Mexico Federico Gomez; México Fil: Bortolini, Maria Cátira. Universidade Federal do Rio Grande do Sul; Brasil Fil: Gallo, Carla. Universidad Peruana Cayetano Heredia; Perú Fil: Bedoya, Gabriel. Universidad de Antioquia; Colombia Fil: Rothhammer, Francisco. Universidad de Chile; Chile Fil: González José, Rolando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Ciencias Sociales y Humanas; Argentina Fil: Ruiz-Linares, Andres. Fudan University; China. Anthropologie Bio-culturelle, Droit, Éthique & Fil: Stephens, Christopher R.. Universidad Nacional Autónoma de México. Instituto de Ciencias Nucleares; México Fil: Velazquez Cruz, Rafael. Instituto Nacional de Medicina Genómica Mexico; México Fil: Fernández del Valle Laisequilla, Cecilia. Productos Medix; México Fil: Reyes-García, Juan G.. INSTITUTO POLITÉCNICO NACIONAL (IPN); Fil: Barranco Garduño, Lina M.. Instituto Nacional de Enfermedades Respiratorias; México Fil: Carrasco-Portugal, Miriam del C.. Instituto Nacional de Enfermedades Respiratorias; México Fil: Flores-Murrieta, Francisco J.. Instituto Nacional de Enfermedades Respiratorias; México. INSTITUTO POLITÉCNICO NACIONAL (IPN); Fil: Vargas Alarcón, Gilberto. Instituto Nacional de Cardiologia Ignacio Chavez; México Fil: Aguilar Salinas, Carlos A.. Escuela de Medicina y Ciencias de la Salud Tecsalud; México. Instituto Nacional de la Nutrición Salvador Zubiran; México Fil: Villarreal Molina, Teresa. Inmegen; México Fil: Canizales Quinteros, Samuel. Instituto Nacional de Medicina Genómica Mexico; México

Vitamin D-binding protein (VDBP) is encoded by the GC gene and is an active participant in the control of bone metabolism. However, the effect of its major variants on VDBP concentration and bone mineral density (BMD) remains unclear. Our aim was to analyze the effect of major GC variants on serum VDBP concentration and BMD. We recruited individuals from the Health Workers Cohort Study, which includes employees of the Mexican Institute of Social Security (IMSS). A total of 1853 adults were included. The single nucleotide polymorphisms (SNPs) rs7041 and rs4588 were genotyped to identify the three best characterized haplotypes of GC. Serum VBDP, 25(OH)D and BMD were also measured. Among women, the G allele of rs7041 was associated with higher VDBP and BMD compared to homozygous TT. The A allele of rs4588 was associated with lower VDBP and BMD compared to CC homozygous. In men, GC variants were only associated with VDBP levels. We did not observe an association between free/bioavailable 25(OH)D and BMD in men and women. Our results support an association of VDBP in bone health. The G and C alleles, from rs7041 and rs4588, respectively, are associated with high concentrations of VDBP and BMD in this sample of Mexican postmenopausal women.

Osteosarcoma is the most common malignant bone tumor. Early diagnosis remains a major challenge, mainly because of the lack of specific biomarkers. We performed miRNAs expression analysis through qPCR in affected and paired healthy bone derived from osteosarcoma patients. Hierarchical clustering using the top ten miRNAs with differential expression showed two main clusters. One integrated by patients with the presence of metastasis or relapse and the other without these complications. Further pathway enrichment analysis reduced to four main miRNAs, hsa-miR-486-3p, hsa-miR-355-5p, hsa-miR-34a-5p and hsa-miR-1228-3p. Afterwards, we compared patients with and without metastasis, the function enrichment analysis along with review of relevant literature, showed that hsa-miR-93-5p and hsa-miR-28-5p were associated with metastasis development. Our results support the relevance of miRNAs in the pathogenesis of osteosarcoma and contribute with evidence regarding the potential role of miRNAs as potential biomarkers. More studies are needed to define the most informative miRNAs in osteosarcoma patients.

Osteoporosis is the most frequent disorder of bone metabolism, owing to an alteration between osteoclast and osteoblast activity, which results from the interaction of genetic, environmental, and epigenetic factors. microRNAs, small non-coding RNAs of around 22 nucleotides with important regulatory roles in gene regulation, that target mRNAs for post-transcriptional destabilization have been suggested as biomarkers in several disorders. In this work, we used small RNA sequencing to identify microRNAs from peripheral blood monocytes that were differentially expressed between non-osteoporotic and osteoporotic Mexican postmenopausal women, to elucidate the potential role of microRNAs as non-invasive marker candidates in osteoporosis. We identified six candidate microRNAs: four were up-regulated (miR-708-5p, miR-34b-5p, miR-3161, miR-328-5p), while two were down-regulated (miR-4422 and miR-939-3p) in osteoporotic women. Differential expression was validated by quantitative RT-PCR and only the upregulation of miR-708-5p was found to be statistically significant. Bioinformatic analysis of target genes for miR-708-5p showed 15 signaling pathways related to bone metabolism. Since monocytes are osteoclast precursors, 10 potential target genes present in these pathways and related to osteoclastogenesis were identified (AKT1, AKT2, CCND1, PARP1, SMAD3, CXCL5, FKBP5, MAP2K3, MMP2, and IKBKG). Five of them were found to be down-regulated according to microarray expression data. This is the first time that miR-708-5p has been identified in peripheral blood monocytes and associated with postmenopausal osteoporosis. Our results suggest that miR-708-5p reduces the expression of AKT1, AKT2, PARP1 FKBP5, and MP2K3 in peripheral blood monocytes contributing to an osteoporotic phenotype and could be a candidate marker for postmenopausal osteoporosis in Mexican population. IMPACT STATEMENT: This is the first study in which hsa-miR-708-5p has been identified in peripheral blood monocytes (osteoclast precursors) and associated with postmenopausal osteoporosis through small RNA-Sequencing, in an Admixed Mexican Mestizo population. By conducting in silico and bioinformatic analyzes, we identified target genes and important signaling pathways involved in bone metabolism pointing hsa-miR-708-5p as a candidate marker for osteoporosis in Mexican population. These approaches provide a landscape of the post-transcriptional regulation, which can be useful for the management of postmenopausal osteoporosis along with the potential use of microRNAs as markers for its early detection.

Objective. To examine different health outcomes that are associated with specific lifestyle and genetic factors. Materials and methods. From March 2004 to April 2006, a sample of employees from three different health and academic institutions, as well as their family members, were enrolled in the study after providing informed consent. At baseline and follow-up (2010-2013), participants completed a self-administered questionnaire, a physical examination, and provided blood samples. Results. A total of 10 729 participants aged 6 to 94 years were recruited at baseline. Of these, 70% were females, and 50% were from the Mexican Social Security Institute. Nearly 42% of the adults in the sample were overweight, while 20% were obese. Conclusion. Our study can offer new insights into disease mechanisms and prevention through the analysis of risk factor information in a large sample of Mexicans.

There is scarce information about the link between specific single-nucleotide polymorphisms (SNPs) and risk of liver disease among Latinos, despite the disproportionate burden of disease among this population. Our aim was to investigate nine SNPs in or near the following genes: PNPLA3, LYPLAL1, PPP1R3B, GCKR, NCAN, IRS1, PPARG, and ADIPOR2 and examine their association with persistently elevated alanine aminotransferase (ALT) or aspartate aminotransferase (AST) levels in Mexican adults. Data and samples were collected from 741 participants in the Mexican Health Worker Cohort Study, in Cuernavaca, Mexico. We identified 207 cases who had persistently elevated levels of ALT or AST (≥40 U/L) and 534 controls with at least two consecutive normal ALT or AST results in a 6 month period, during 2004-2006 and 2011-2013. TaqMan assays were used to genotype the SNPs. The risk allele of PNPLA3 rs738409 was found to be associated with persistently elevated levels of ALT or AST, adjusting for age, sex, BMI, type 2 diabetes, and ancestry: (OR 2.28, 95% CI 1.13, 4.58). A significant association was found between the LYPLAL1, PPP1R3B, and GCKR risk alleles and elevated ALT or AST levels among overweight/obese adults. These results suggest that among Mexicans, the PNPLA3 (rs738409), LYPLAL1 (rs12137855), PPP1R3B (rs4240624), and GCKR (rs780094) polymorphisms may be associated with a greater risk of chronic liver disease among overweight adults. This study is the first to examine these nine SNPs in a sample of adults in Mexico.

Extensive research has shown that aberrant expression of microRNAs (miRNAs) plays an important role in innate and adaptive immune responses. The rs2910164 polymorphism has been identified as a functional variant, which affects the transcription and expression level of miR-146a and, thereby, contributes to the pathogenesis of several inflammatory and autoimmune diseases. To investigate whether the rs2910164 G/C polymorphism was associated with asthma, systemic lupus erythematosus (SLE) or juvenile rheumatoid arthritis (JRA), we performed an association study in a pediatric Mexican cohort. We included 979 pediatric patients (asthma: 402, SLE: 367 and JRA: 210) and 531 control subjects without inflammatory or immune diseases. Genotyping was performed using the 5' exonuclease technique. The genotype distribution of the rs2910164 polymorphism was in Hardy-Weinberg equilibrium in each group. No significant differences were detected in the distribution of this polymorphism between cases and controls (P = 0.108, 0.609 and 0.553 for subjects with asthma, JRA and SLE, respectively). However, stratification by gender showed a statistically significant difference between asthmatic and control females, where the C allele was significantly associated with protection to asthma (odds ratio = 0.694, 95% confidence interval 0.519-0.929, P = 0.0138). Our results provide evidence that rs2910164 may play a role in the susceptibility to childhood-onset asthma, but not SLE or JRA in Mexicans. Further association studies may contribute to determining the role of miR-146a single-nucleotide polymorphisms in immune-mediated diseases.

In several populations CFTR mutations, as well as IVS8-Tn CFTR polymorphism, have been associated with congenital bilateral absence of the vas deferens (CBAVD) and idiopathic obstructive azoospermia diseases. However, the involvement of these mutations in infertility of Mexican males has not been elucidated.We investigated whether CFTR mutations and IVS8-Tn(TG)m polymorphisms are associated with infertility in azoospermic Mexican patients.Sixteen CBAVD and 33 idiopathic azoospermic cases were included. The CFTR gene was sequenced in all CBAVD cases. In the idiopathic azoospermic patients, the p.F508del, p.G542X, p.N1303K, p.S549N, p.I507del, and p.R117H mutations and those detected in our CBAVD cases were screened.The p.F508del, p.G85E, p.D1152H, and p.W1089X mutations were found in 3 CBAVD patients (18.8%). None of the 9 CFTR mutations screened for in idiopathic azoospermic were found; however, we documented a high frequency of the Gln1463Gln polymorphism in comparison with healthy controls (20% vs 6%; p=0.0029).These data showed that the CFTR mutations but not the IVS8-Tn polymorphism are involved in CBAVD etiology in a Mexican population. Nevertheless, other screening strategies should be used to rule out the implication of CFTR mutations in idiopathic azoospermic disease.

Systemic lupus erythematosus (SLE) is an autoimmune disease associated with oxidative stress and characterized by chronic inflammation. Kidney malfunction, an aggressive characteristic of this disease, is not present in all affected individuals. The Nrf2-Keap1 pathway is important in protecting against oxidative stress and inflammation. Mouse models and genome-wide scans have suggested NRF2 (Nuclear factor (erythroid-derived 2)-like 2) as a candidate gene for susceptibility to SLE. We therefore investigated whether NRF2 polymorphisms are associated with childhood-onset SLE in a Mexican Mestizo population. Two single nucleotide polymorphisms (SNPs) were genotyped by TaqMan® assays in 362 patients with childhood-onset SLE and 379 controls. We found no significant association between susceptibility to SLE and NRF2 polymorphisms. However, after population stratification by gender, the heterozygous genotype of the -653G/A SNP was significantly associated with nephritis in females only [OR = 1.81, CI (1.04—3.12), p = 0.032]. This association was stronger in females affected with severe nephritis [classes IV—VI; OR = 2.16, CI (1.12—4.15), p = 0.019]. Our results suggest that NRF2 is not associated with susceptibility to childhood-onset SLE, but it could confer a risk for developing kidney malfunction in SLE-affected individuals.

There is a great deal of evidence that points to the association of the tumor necrosis factor-alpha ( TNF- α) gene as a common genetic factor in the pathogenesis of diseases that are caused by inflammatory and/or autoimmune etiologies. Two single nucleotide polymorphisms (SNPs) identified in the TNF -α promoter region have been associated with disease susceptibility and severity. We investigated whether −308G/A and −238G/A TNF-α polymorphisms were associated with asthma, systemic lupus erythematosus (SLE), and juvenile rheumatoid arthritis (JRA) in a pediatric Mexican population. In a case-control study of 725 patients (asthma: 226, JRA: 171, and SLE: 328) and 400 control subjects, the participants were analyzed using the allelic discrimination technique. The genotype distribution of both TNF -α polymorphisms was in Hardy-Weinberg equilibrium in each group. However, there were significant differences in the allele frequency of TNF -α-308A between the patients and the healthy controls. This allele was detected in 2.9% of the controls, 6.0% of asthmatic and JRA patients ( p = 0.002 and p = 0.0086), and 6.7% of SLE patients ( p = 0.00049); statistical significance was maintained after ancestry stratification (asthma: p = 0.0143, JRA: p = 0.0083, and SLE: p = 0.0026). Stratification by gender showed that the risk for the −308A allele in asthma and JRA was greater in females (OR = 4.16, p = 0.0008 and OR = 4.4, p = 0.0002, respectively). The TNF -α -238A allele showed an association only with JRA in males (OR = 2.89, p = 0.004). These results support the concept that the TNF-α gene is a genetic risk factor for asthma, SLE, and JRA in the pediatric Mexican population.

This study was conducted to determine the frequency of the most common fusion genes in Mexican pediatric patients with acute lymphoblastic leukemia (ALL). Molecular analysis using RT-PCR was carried out in 53-blood samples: 52 patients with de novo ALL and one with relapsed ALL. The ETV6-RUNX1 fusion was found in 7 cases (13.5%), BCR-ABL fusion was detected in 2 cases (3.8%), and 6 patients (11.5%) expressed the chimeric gene E2A-PBX1. The prevalence of E2A-PBX1 is one of the highest that has been described thus far in childhood ALL. Furthermore, we detected both the BCR-ABL, and E2A-PBX1 fusion in the relapsed patient. With regards to the immunophenotype, ETV6-RUNX1 was expressed in both pre-B and T-cell cases, while the presence of E2A-PBX1 and BCR-ABL was associated with the pre-B ALL phenotype. The prevalence of E2A-PBX1 in Mexican pediatric cases supports the existence of ethnic differences in the frequency of molecular markers of ALL.

A regulatory single nucleotide polymorphism (SNP) PD1.3G/A located on programmed cell death 1 (PDCD1) gene, was shown to be involved in susceptibility to systemic lupus erythematosus (SLE) in Swedish, European American, and Mexican cases. However, association to childhood-onset SLE has not been analyzed. The aim of this study was to investigate the association of PDCD1 polymorphisms and haplotypes with susceptibility to childhood-onset SLE in Mexican population. Three PDCD1 SNPs, PD1.3G/A, PD1.5C/T, PD1.6G/A, were analyzed in 250 childhood-onset SLE Mexican patients and 355 healthy controls in a case-control association study. Polymorphisms were genotyped by TaqMan technology. Stratification analysis was performed on the SLE cohort to investigate the SNP association with renal disorder. In addition, haplotypes were constructed with these three SNPs. The PD1.3A allele was significantly associated to childhood-onset SLE (P=0.0019, odds ratio (OR) 2.73, 95% confidence interval (95% CI) 1.35-5.56). The other PDCD1 SNPs did not show association. A total of 155 patients (62%) had nephritis, and no association was observed with PDCD1 SNPs. The ACG haplotype (PD1.3A, PD1.5C, PD1.6G) included almost all PD1.3A alleles, and it was more frequent in SLE patients (5.5%) than in controls (2.1%) (P=0.003; OR 2.73, 95% CI 1.37-5.46). The haplotype structure in Mexican controls was significantly different from those reported in Spanish and Swedish. Our results support association of the PD1.3A SNP to susceptibility of childhood-onset SLE in Mexican population and does not show association to lupus nephritis in this age group.

Hypertension is a major public health problem affecting about 30% of the adult population and is associated with an increased risk of developing metabolic and cardiovascular disease. Recent reports have shown that the T-cadherin receptor characteristically expressed on endothelial and vascular smooth muscle cells is involved in hypertension. The aim of the present study was to evaluate the role of cadherin-13 ( CDH13 ) gene polymorphisms as susceptibility markers for hypertension in Mexican population. Six CDH13 polymorphisms (rs11646213, rs11646411, rs6563943, rs3096277, rs3784990 and rs254340) were genotyped by 5′ exonuclease TaqMan assays in a group of 644 hypertensive and 765 non-hypertensive individuals. Under co-dominant, recessive, and additive models, the CDH13 T > A (rs11646213) polymorphism was associated with decreased risk of developing hypertension when compared to non-hypertensive individuals (OR = 0.61, 95% CI: 0.42–0.89, P co-dom = 0.019; OR = 0.63, 95% CI: 0.46–0.87, P res = 0.005; OR = 0.80, 95% CI: 0.66–0.96, P add = 0.016, respectively). All models were adjusted by gender, age, body index mass, type II diabetes mellitus, alcohol consumption, dyslipidemia and smoking habit. Linkage disequilibrium analysis showed one haplotype ( TCACGG ) with decreased frequency in hypertensive when compared to non-hypertensive individuals (OR = 0.52, 95% CI: 0.33–0.82, P = 0.0053). In summary, our data suggests that the CDH13 T > A (rs11646213) polymorphism is associated with decreased risk of developing hypertension in the Mexican population. In addition, it was possible to distinguish one haplotype associated with decreased risk and two for increased risk of develop hypertension.

Background Osteoporosis, a disease characterized by low bone mineral density (BMD), is an important health problem in Mexico. BMD is a highly heritable trait, with heritability estimates of 50-85%. Several candidate genes have been evaluated to identify those involved in BMD variation and the etiology of osteoporosis. This study investigated the possible association of single-nucleotide polymorphisms (SNPs) in the MEF2C, SOST and JAG1 genes with bone mineral density (BMD) variation in postmenopausal Mexican-Mestizo women. Methods Four hundred unrelated postmenopausal women were included in the study. Risk factors were recorded and BMD was measured in total hip, femoral neck and lumbar spine using dual-energy X-ray absorptiometry. In an initial stage, a total of twenty-five SNPs within or near SOST gene and seven SNPs in the JAG1 gene were genotyped using a GoldenGate assay. In a second stage, three MEF2C gene SNPs were also genotyped and SOST and JAG1 gene variants were validated. Real time PCR and TaqMan probes were used for genotyping. Results Linear regression analyses adjusted by age, body mass index and ancestry estimates, showed that five SNPs in the SOST gene were significantly associated with BMD in total hip and femoral neck but not lumbar spine. The lowest p value was 0.0012, well below the multiple–test significance threshold (p = 0.009), with mean effect size of -0.027 SD per risk allele. We did not find significant associations between BMD and MEF2C/JAG1 gene variants [rs1366594 “A” allele: β = 0.001 (95% CI -0.016; 0.017), P = 0.938; rs2273061 “G” allele: β = 0.007 (95% CI -0.007; 0.023), p = 0.409]. Conclusions SOST polymorphisms may contribute to total hip and femoral neck BMD variation in Mexican postmenopausal women. Together, these and prior findings suggest that this gene may contribute to BMD variation across populations of diverse ancestry. Electronic supplementary material The online version of this article (doi:10.1186/1471-2474-15-400) contains supplementary material, which is available to authorized users.

Variations in gene copy number (CNV) have been recognised as a hereditable source of susceptibility in human complex diseases. Recent studies have shown that Tlr7 gene dosage has a significant contribution in the autoimmune-enhancing effect in mouse models of systemic lupus erythematosus (SLE). A study was therefore performed to investigate whether CNVs in TLR7 contribute to the genetic component of childhood-onset SLE.A case-control association study was performed in 328 Mexican children with SLE and 403 healthy controls. Determination of CNVs of TLR7 was achieved by real-time PCR using the ΔΔCt method. Expression levels of TLR7 and interferon α (IFNα) were determined in 23 patients. In addition, a stratification analysis was performed to investigate the association of TLR7 gene copy number (CN) with lupus nephritis.A significant increase was found in the relative TLR7 gene CN in females patients with SLE compared with female controls (p0.0001). However, logistic regression analysis by gender showed a higher OR (OR 6.61, p=0.005) in male patients with1 copy of TLR7 than in female patients with2 copies (OR 3.07, p0.0001). This association was not observed with lupus nephritis. TLR7 mRNA levels correlated significantly with TLR7 CN and with IFNα mRNA levels.These results show that an increase in TLR7 CN is a risk factor for childhood-onset SLE and provide new evidence for a role for X-linked gene dosage in SLE susceptibility. There is also evidence to suggest that TLR7 may be involved in the pathogenesis of SLE through the induction of IFNα.

Ifosfamide blood concentrations are necessary to monitor its therapeutic response, avoiding any adverse effect. We developed and validated an analytical method by UPLC-MS/MS to quantify ifosfamide in dried blood spots (DBS). Blood samples were collected on Whatman 903® filter paper cards. Five 3 mm disks were punched out from each dried blood spot. Acetonitrile and ethyl acetate were used for drug extraction. Chromatographic separation was carried out in an Acquity UPLC equipment with a BEH-C18 column, 2.1 x 100 mm, 1.7 μm (Waters®). The mobile phase consisted in 5 mM ammonium formate and methanol:acetonitrile (40:48:12 v/v/v) at 0.2 mL/min. LC-MS/MS detection was done by ESI+ and multiple reaction mode monitoring, ionic transitions were m/z1+ 260.99 > 91.63 for ifosfamide and 261.00 > 139.90 for cyclophosphamide (internal standard). This method was linear within a 100–10000 ng/mL range and it was accurate, precise and selective. Ifosfamide samples in DBS were stable for up to 52 days at -80°C. The procedure was tested in 14 patients, ages 1 month to 17 years (9 males and 5 females), with embryonic tumours treated with ifosfamide, alone or combined, at a public tertiary referral hospital. Ifosfamide blood levels ranged from 11.1 to 39.7 μmol/L at 12 hours after the last infusion, while 24-hour levels ranged from 0.7–19.7 μmol/L. The median at 12 hours was 19.5 μmol/L (Q25 14.4–Q75 29.0) and 3.8 μmol/L (Q25 1.5–Q75 9.9) at 24 hours, p