Epidemiology of childhood acute leukemias in marginalized populations of the central-south region of Mexico: results from a population-based registry

Introduction

Acute leukemias (AL) are the main types of cancer in children worldwide. In Mexico, they represent one of the main causes of death in children under 20 years of age. Most of the studies on the incidence of AL in Mexico have been developed in the urban context of Greater Mexico City and no previous studies have been conducted in the central-south of the country through a population-based study. The aim of the present work was to identify the general and specific incidence rates of pediatric AL in three states of the south-central region of Mexico considered as some of the marginalized populations of Mexico (Puebla, Tlaxcala, and Oaxaca).

Methods

A population-based study was conducted. Children aged less than 20 years, resident in these states, and newly diagnosed with AL in public/private hospitals during the period 2021-2022 were identified. Crude incidence rates (cIR), standardized incidence rates (ASIRw), and incidence rates by state subregions (ASIRsr) were calculated. Rates were calculated using the direct and indirect method and reported per million children under 20 years of age. In addition, specific rates were calculated by age group, sex, leukemia subtype, and immunophenotype.

Results

A total of 388 cases with AL were registered. In the three states, the ASIRw for AL was 51.5 cases per million (0-14 years); in Puebla, it was 53.2, Tlaxcala 54.7, and Oaxaca de 47.7. In the age group between 0-19 years, the ASIRw were 44.3, 46.4, 48.2, and 49.6, in Puebla, Tlaxcala, and Oaxaca, respectively. B-cell acute lymphoblastic leukemia was the most common subtype across the three states.

Conclusion

The incidence of childhood AL in the central-south region of Mexico is within the range of rates reported in other populations of Latin American origin. Two incidence peaks were identified for lymphoblastic and myeloid leukemias. In addition, differences in the incidence of the disease were observed among state subregions which could be attributed to social factors linked to the ethnic origin of the inhabitants. Nonetheless, this hypothesis requires further investigation.

Evidence of spatial clustering of childhood acute lymphoblastic leukemia cases in Greater Mexico City: report from the Mexican Inter-Institutional Group for the identification of the causes of childhood leukemia

Background

A heterogeneous geographic distribution of childhood acute lymphoblastic leukemia (ALL) cases has been described, possibly, related to the presence of different environmental factors. The aim of the present study was to explore the geographical distribution of childhood ALL cases in Greater Mexico City (GMC).

Methods

A population-based case-control study was conducted. Children <18 years old, newly diagnosed with ALL and residents of GMC were included. Controls were patients without leukemia recruited from second-level public hospitals, frequency-matched by sex, age, and health institution with the cases. The residence address where the patients lived during the last year before diagnosis (cases) or the interview (controls) was used for geolocation. Kulldorff's spatial scan statistic was used to detect spatial clusters (SCs). Relative risks (RR), associated p-value and number of cases included for each cluster were obtained.

Results

A total of 1054 cases with ALL were analyzed. Of these, 408 (38.7%) were distributed across eight SCs detected. A relative risk of 1.61 (p<0.0001) was observed for the main cluster. Similar results were noted for the remaining seven ones. Additionally, a proximity between SCs, electrical installations and petrochemical facilities was observed.

Conclusions

The identification of SCs in certain regions of GMC suggest the possible role of environmental factors in the etiology of childhood ALL.

Association between genetic variants of membrane transporters and the risk of high-grade hematologic adverse events in a cohort of Mexican children with B-cell acute lymphoblastic leukemia

Background

Advances in the understanding of the pathobiology of childhood B-cell acute lymphoblastic leukemia (B-ALL) have led towards risk-oriented treatment regimens and markedly improved survival rates. However, treatment-related toxicities remain a major cause of mortality in developing countries. One of the most common adverse effects of chemotherapy in B-ALL is the hematologic toxicity, which may be related to genetic variants in membrane transporters that are critical for drug absorption, distribution, and elimination. In this study we detected genetic variants present in a selected group genes of the ABC and SLC families that are associated with the risk of high-grade hematologic adverse events due to chemotherapy treatment in a group of Mexican children with B-ALL.

Methods

Next generation sequencing (NGS) was used to screen six genes of the ABC and seven genes of the SLC transporter families, in a cohort of 96 children with B-ALL. The grade of hematologic toxicity was classified according to the National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE) version 5.0, Subsequently, two groups of patients were formed: the null/low-grade (grades 1 and 2) and the high-grade (grades 3 to 5) adverse events groups. To determine whether there is an association between the genetic variants and high-grade hematologic adverse events, logistic regression analyses were performed using co-dominant, dominant, recessive, overdominant and log-additive inheritance models. Odds ratio (OR) and 95% confidence intervals (95% CI) were calculated.

Results

We found two types of associations among the genetic variants identified as possible predictor factors of hematologic toxicity. One group of variants associated with high-grade toxicity risk: ABCC1 rs129081; ABCC4 rs227409; ABCC5 rs939338, rs1132776, rs3749442, rs4148575, rs4148579 and rs4148580; and another group of protective variants that includes ABCC1 rs212087 and rs212090; SLC22A6 rs4149170, rs4149171 and rs955434.

Conclusion

There are genetic variants in the SLC and ABC transporter families present in Mexican children with B-ALL that can be considered as potential risk markers for hematologic toxicity secondary to chemotherapeutic treatment, as well as other protective variants that may be useful in addition to conventional risk stratification for therapeutic decision making in these highly vulnerable patients.

The genetic risk of acute lymphoblastic leukemia and its implications for children of Latin American origin

Acute lymphoblastic leukemia (ALL) is the most common cancer in children, and disproportionately affects children of Hispanic/Latino ethnicity in the United States, who have the highest incidence of disease compared with other racial/ethnic groups. Incidence of childhood ALL is similarly high in several Latin American countries, notably in Mexico, and of concern is the rising incidence of childhood ALL in some Hispanic/Latino populations that may further widen this disparity. Prior studies have implicated common germline genetic variants in the increased risk of ALL among Hispanic/Latino children. In this review, we describe the known disparities in ALL incidence as well as patient outcomes that disproportionately affect Hispanic/Latino children across the Americas, and we focus on the role of genetic variation as well as Indigenous American ancestry in the etiology of these disparities. Finally, we discuss future avenues of research to further our understanding of the causes of the disparities in ALL incidence and outcomes in children of Latin American origin, which will be required for future precision prevention efforts.

Maternal diet in pregnancy and acute leukemia in infants: a case-control study in Mexico City

Introduction

Epidemiological studies around the world on acute leukemia (AL) and risk factors in infants are scarce. Infant AL has been proposed to originate in utero, which facilitates its study by establishing a short exposure time in pregnant women to environmental and dietary factors that could contribute to the risk of or protection against leukemia. We hypothesized that maternal diet during pregnancy may be an important factor involved in AL in offspring.

Methods

We conducted a hospital-based case-control study from 2010 to 2019 on maternal diet during pregnancy in nine high-specialty public hospitals of different health institutions that diagnose and offer treatment to children with AL in Mexico City. Cases (n=109) were children ≤24 months of age with de novo diagnosis of AL, and controls (n=252) were children obtained in hospitals from second-level medical care matched for age, sex, and health institution. Maternal diet during pregnancy was obtained by a semiquantitative food frequency questionnaire. Unconditional logistic regression models were used to assess the association between food groups and infant AL. Potential confounders were assessed by constructing directed acyclic graphs (DAGs) with Dagitty software in which adjusted options were identified for the construction of unconditional logistic regression models.

Results

Cases were slightly predominantly female (52.3%). The years of education of the mother in cases and controls was 0-9 on average, and those who reported smoking cigarettes and consuming alcohol during pregnancy did so at a low frequency. Regarding the mother's diet, the main findings were that the consumption of allium vegetables during pregnancy was inversely associated with AL for medium and high consumption (OR=0.26, 95% CI 0.14-0.46; P-trend< 0.001). In contrast, the high consumption of high-fat dairy products had a positive association with AL (OR=2.37, 95% CI 1.30-4.34; P-trend<0.001). No association was found between consumption of topoisomerase II inhibitor foods during pregnancy and AL.

Conclusion

The results suggest that maternal intake during pregnancy of allium vegetables, specifically garlic, is inversely associated with the development of AL in children ≤24 months old. On the other hand, consumption of high-fat dairy products is positively associated with AL in children ≤24 months old.

Maternal dietary patterns and acute leukemia in infants: results from a case control study in Mexico

Background

Childhood cancer is the leading cause of disease-related mortality among children aged 5-14 years in Mexico, with acute leukemia being the most common cancer among infants. Examining the overall dietary patterns allows for a comprehensive assessment of food and nutrient consumption, providing a more predictive measure of disease risk than individual foods or nutrients. This study aims to evaluate the association between maternal dietary patterns during pregnancy and the risk of acute leukemia in Mexican infants.

Methods

A hospital-based case-control study was conducted, comparing 109 confirmed acute leukemia cases with 152 age-matched controls. All participants (≤24 months) were identified at hospitals in Mexico City between 2010 and 2019. Data on a posteriori dietary patterns and other relevant variables were collected through structured interviews and dietary questionnaires. Multivariate logistic regression was employed to estimate the association between maternal dietary patterns during pregnancy and the risk of acute leukemia in infants.

Results

The "Balanced & Vegetable-Rich" pattern, characterized by a balanced consumption of various food groups and higher vegetable intake, exhibited a negative association with acute leukemia when compared to the "High Dairy & Cereals" Pattern (adjusted odds ratio [OR] = 0.51; 95% confidence interval [CI]: 0.29, 0.90). We observed that mothers who gave birth to girls and adhered to a healthy dietary pattern during pregnancy exhibited significantly lower odds of their children developing AL compared to those who gave birth to boys [OR = 0.32 (95% CI 0.11, 0.97)]. Our results underscore the significance of maternal nutrition as a modifiable factor in disease prevention and the importance of prenatal health education.

Infections and risk factors for infection-related mortality after pediatric allogeneic hematopoietic stem cell transplantation in Mexico: A single center retrospective study

OBJECTIVE

To identify the type of infections and risk factors for infection-related mortality (IRM) after allogeneic hematopoietic stem cell transplantation (HSCT).

METHODS

Retrospective cohort study of patients <16 years of age treated in 2010-2019 was conducted. Unadjusted hazard ratios (HR) and adjusted hazard ratios (aHR) with 95% confidence intervals (95% CIs) were estimated using Cox regression. Cumulative incidence was calculated.

RESULTS

Data for 99 pediatric patients were analyzed. The myeloablative conditioning was the most used regimen (78.8%) and the hematopoietic stem cell source was predominantly peripheral blood (80.8%). Primary graft failure occurred in 19.2% of patients. Frequency of acute graft-versus-host disease was 46.5%. Total of 136 infectious events was recorded, the most common of which were bacterial (76.4%) followed by viral infection (15.5%) and then fungal infection (8.1%). The best predictors for infection subtypes where the following: a) for bacterial infection (the age groups of 10.1-15 years: aHR = 3.33; 95% CI: 1.62-6.85 and. >15 years: aHR = 3.34; 95% CI: 1.18-9.45); b) for viral infection (graft versus host disease: aHR = 5.36; 95% CI: 1.62-17.68), however, for fungal infection statistically significant predictors were not identified. Related mortality was 30% (n = 12). Increased risk for infection-related mortality was observed in patients with unrelated donor and umbilical cord stem cells recipients (HR = 3.12; 95% CI: 1.00-9.85).

CONCLUSIONS

Frequencies of infections and infection-related mortality appear to be similar to those reported. Unrelated donors and stem cells from umbilical cord recipients were associated with a high risk of mortality.

Pilot study on the effect of supplementation with long-chain ω-3 polyunsaturated fatty acids on body composition in children with acute lymphoblastic leukemia: randomized clinical trial

BACKGROUND

N-3 polyunsaturated fatty acids (LCPUFA-ω3), particularly docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) might have beneficial effects on lean mass and fat mass synthesis.

OBJECTIVE

To investigate the effect of LCPUFA-ω3 supplementation on body composition changes in children with acute lymphoblastic leukemia (ALL) at remission and three months (3 mo) after supplementation.

METHODS

This randomized controlled trial enrolled 72 children (3-13 y) with newly diagnosed ALL (placebo group [500 mg sunflower oil]: 36 patients; LCPUFA-ω3 group [225 mg DHA, 45 mg EPA]: 36 patients). LCPUFA-ω3 was administered at 0.100 g/kg of body weight/day for 3 mo. Both groups were provided with an oral milkshake supplement.

MAIN OUTCOMES AND MEASURES

Body composition was measured at diagnosis, remission, and 3 months after supplementation by dual-energy X-ray absorptiometry (DXA). Red blood cell fatty acid analyses were performed with gas chromatography. Student's t test compared the percentage changes in body weight, total body fat percentage (TBFP), and lean body mass (LBM) between the groups. The Mann-Whitney U test was used to compare the groups, and the Friedman range test and Wilcoxon signed rank test were used for intratreatment comparisons. Spearman correlation coefficients were calculated for LBM and erythrocyte LCPUFA-ω3 content.

RESULTS

LBM decreased significantly in both groups. This loss was greater in the placebo group than in the LCPUFA-ω3 group at remission (p = 0.044) and at 3 months of supplementation (p = 0.039). There were significant and progressive increases in DHA and EPA concentrations in the LCPUFA-ω3 group (p < 0.001). LBM at remission was directly correlated with increased DHA (r = 0.487, p = 0.034) and EPA (r = 0.499, p = 0.030) erythrocytes in the LCPUFA-ω3 group.

CONCLUSION

At ALL diagnosis and during the first three months of treatment, 100 mg/kg of body weight/d DHA and EPA decreased LBM loss and allowed the incorporation of fatty acids into cell membranes (clinicaltriasl.gov #: NCT01051154).

Not All Populations of Hispanic Children Have an Increased Frequency of Acute Lymphoblastic Leukemia

The frequency of acute lymphoblastic leukemia (ALL) has been reported with a higher incidence among the populations of Hispanic children. However, in the article by Montes-Rodríguez and colleagues, they found that in the Puerto Rican population, the frequency was below the incidence reported for the U.S. Hispanic pediatric population, but they found that the incidence of ALL had an annual increase of 5%. In other Hispanic pediatric populations during the 1980s, the incidence of ALL was found to be even lower than the general rate in the United States. However, in less than 20 years that incidence had already been exceeded. It is evident that the Hispanic pediatric population is more susceptible to develop ALL than other populations, so it is important to consider that what is happening to the pediatric population of Puerto Rico gives us a great opportunity to identify risk factors that could potentially explain this increase. It is more likely that the risk factors that are capable of causing ALL could be identified in their role in the origin of the disease in populations with high susceptibility, given the greater number of cases of ALL that said factor is causing in that population. See related article by Montes-Rodríguez et al., p. 1030.

NK cells with decreased expression of multiple activating receptors is a dominant phenotype in pediatric patients with acute lymphoblastic leukemia

NK cells have unique attributes to react towards cells undergoing malignant transformation or viral infection. This reactivity is regulated by activating or inhibitory germline encoded receptors. An impaired NK cell function may result from an aberrant expression of such receptors, a condition often seen in patients with hematological cancers. Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer worldwide and NK cells have emerged as crucial targets for developing immunotherapies. However, there are important gaps concerning the phenotype and behavior of NK cells during emergence of ALL. In this study we analyze the phenotype and function of NK cells from peripheral blood in pediatric patients with ALL at diagnosis. Our results showed that NK cells exhibited an altered phenotype highlighted by a significant reduction in the overall expression and percent representation of activating receptors compared to age-matched controls. No significant differences were found for the expression of inhibitory receptors. Moreover, NK cells with a concurrent reduced expression in various activating receptors, was the dominant phenotype among patients. An alteration in the relative frequencies of NK cells expressing NKG2A and CD57 within the mature NK cell pool was also observed. In addition, NK cells from patients displayed a significant reduction in the ability to sustain antibody-dependent cellular cytotoxicity (ADCC). Finally, an aberrant expression of activating receptors is associated with the phenomenon of leukemia during childhood.

Persistently high incidence rates of childhood acute leukemias from 2010 to 2017 in Mexico City: A population study from the MIGICCL

Introduction

Over the years, the Hispanic population living in the United States has consistently shown high incidence rates of childhood acute leukemias (AL). Similarly, high AL incidence was previously observed in Mexico City (MC). Here, we estimated the AL incidence rates among children under 15 years of age in MC during the period 2010-2017.

Methods

The Mexican Interinstitutional Group for the Identification of the Causes of Childhood Leukemia conducted a study gathering clinical and epidemiological information regarding children newly diagnosed with AL at public health institutions of MC. Crude age incidence rates (cAIR) were obtained. Age-standardized incidence rates worldwide (ASIRw) and by municipalities (ASIRm) were calculated by the direct and indirect methods, respectively. These were reported per million population <15 years of age; stratified by age group, sex, AL subtypes, immunophenotype and gene rearrangements.

Results

A total of 903 AL cases were registered. The ASIRw was 63.3 (cases per million) for AL, 53.1 for acute lymphoblastic leukemia (ALL), and 9.4 for acute myeloblastic leukemia. The highest cAIR for AL was observed in the age group between 1 and 4 years (male: 102.34 and female: 82.73). By immunophenotype, the ASIRw was 47.3 for B-cell and 3.7 for T-cell. The incidence did not show any significant trends during the study period. The ASIRm for ALL were 68.6, 66.6 and 62.8 at Iztacalco, Venustiano Carranza and Benito Juárez, respectively, whereas, other municipalities exhibited null values mainly for AML.

Conclusion

The ASIRw for childhood AL in MC is among the highest reported worldwide. We observed spatial heterogeneity of rates by municipalities. The elevated AL incidence observed in Mexican children may be explained by a combination of genetic background and exposure to environmental risk factors.

Underexpression of LINC00173 in TCF3/PBX1-Positive Cases Is Associated With Poor Prognosis in Children With B-Cell Precursor Acute Lymphoblastic Leukemia

Background

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is the most frequent pediatric cancer worldwide. Despite improvements in treatment regimens, approximately 20% of the cases cannot be cured, highlighting the necessity for identifying new biomarkers to improve the current clinical and molecular risk stratification schemes. We aimed to investigate whether LINC00173 is a biomarker in ALL and to explore its expression level in other human cancer types.

Methods

A nested case-control study including Mexican children with BCP-ALL was conducted. LINC00173 expression was evaluated by qRT-PCR using hydrolysis probes. To validate our findings, RNA-seq expression data from BCP-ALL and normal tissues were retrieved from Therapeutically Applicable Research to Generate Effective Treatments (TARGET) and Genotype-Tissue Expression (GTEx) repositories, respectively. LINC00173 expression was also evaluated in solid tumors by downloading available data from The Cancer Genome Atlas (TCGA).

Results

A lower expression of LINC00173 in BCP-ALL cases compared to normal subjects was observed (p < 0.05). ALL patients who carry the TCF3/PBX1 fusion gene displayed lower expression of LINC00173 in contrast to other BCP-ALL molecular subtypes (p < 0.04). LINC00173 underexpression was associated with a high risk to relapse (HR = 1.946, 95% CI = 1.213-3.120) and die (HR = 2.073, 95% CI = 1.211-3.547). Patients with TCF3/PBX1 and underexpression of LINC00173 had the worst prognosis (DFS: HR = 12.24, 95% CI = 5.04-29.71; OS: HR = 11.19, 95% CI = 26-32). TCGA data analysis revealed that underexpression of LINC00173 is also associated with poor clinical outcomes in six new reported tumor types.

Conclusion

Our findings suggest that LINC00173 is a biomarker of poor prognosis in BCP-ALL and other types of cancer. We observed an association between the expression of LINC00173 and TCF3/PBX1 and the risk to relapse and die in BCP-ALL, which is worse in TCF3/PBX1-positive cases displaying underexpression of LINC00173. Experimental studies are needed to provide insight into the LINC00173 and TCF3/PBX relationship.

Low Prevalence of ETV6::RUNX1 Fusion Gene in a Hispanic Population

ETV6::RUNX1 is a genetic rearrangement of good prognosis in children with acute lymphoblastic leukemia (ALL). In Mexico, its prevalence is low in comparison with Caucasian populations. We developed a novel TaqMan one-step RT-qPCR approach to assess the prevalence of four genetic rearrangements in a cohort of Hispanic children with ALL from Mexico City. The prevalence of common fusion gene transcripts was as follows: TCF3::PBX1 7.7%; BCR::ABL1p 190 3.3%; and KMT2A::AFF1 2.8%, and ETV6::RUNX1was observed with low prevalence (10.5%) in comparison to that reported for developed countries. This is consistent with previous findings on Mexican children with ALL and similar to those reported on children from Hispanic populations. The confirmation of a low prevalence of ETV6::RUNX1 in children of a Hispanic origin represents an advancement in the description of genetic factors of ALL in these populations.

Global expression profiling of CD10 + /CD19 + pre-B lymphoblasts from Hispanic B-ALL patients correlates with comparative TARGET database analysis

Mexico City has one of the highest incidences of acute lymphoblastic leukemia (ALL) globally, with patients showing low survival, and high relapse rates. To gain more insight into the molecular features of B-ALL in Mexican children, we isolated CD10 + /CD19 + precursor B lymphoblasts from four bone marrow and nine peripheral blood samples of B-ALL patients using a fluorescence-activated cell sorting protocol. The global gene expression profile (BM vs PB) revealed 136 differentially expressed genes; 62 were upregulated (45.6%) and 74 were downregulated (54.4%). Pearson's correlation coefficient was calculated to determine the similarity between pre-B lymphoblast populations. We selected 26 highly significant genes and validated 21 by RT-qPCR (CNN3, STON2, CALN1, RUNX2, GADD45A, CDC45, CDC20, PLK1, AIDA, HCK, LY86, GPR65, PIK3CG, LILRB2, IL7R, TCL1A, DOCK1, HIST1H3G, PTPN14, CD72, and NT5E). The gene set enrichment analysis of the total expression matrix and the ingenuity pathway analysis of the 136 differentially expressed genes showed that the cell cycle was altered in the bone marrow with four overexpressed genes (PLK1, CDC20, CDC45, and GADD45A) and a low expression of IL7R and PIK3CG, which are involved in B cell differentiation. A comparative bioinformatics analysis of 15 bone marrow and 10 peripheral blood samples from Hispanic B-ALL patients collected by the TARGET program, corroborated the genes observed, except for PIK3CG. We conclude the Mexican and the Hispanic B-ALL patients studied present common driver alterations and histotype-specific mutations that could facilitate risk stratification and diagnostic accuracy and serve as potential therapeutic targets.

Analytical study of RUNX1-RUNXT1, PML-RARA, CBFB-MYH11, BCR-ABL1p210 , and KMT2-MLLT3 in Mexican children with acute myeloid leukemia: A multicenter study of the Mexican interinstitutional group for the identification of the causes of childhood leukemia (MIGICCL)

BACKGROUND

The distribution of RUNX1-RUNXT1, PML-RARA, CBFB-MYH11, BCR-ABL1^p210 , and KMT2A-MLLT3 in the pediatric population with acute myeloid leukemia (AML) in many countries of Latin America is largely unknown. Therefore, we aimed to investigate the frequency of these fusion genes in children with de novo AML from Mexico City, which has one of the highest incidence rates of acute leukemia in the world. Additionally, we explored their impact in mortality during the first year of treatment.

METHODS

We retrospectively analyzed the presence of RUNX1-RUNXT1, PML-RARA, CBFB-MYH11, BCR-ABL1^p210 , and KMT2A-MLLT3 by RT-PCR among 77 patients (<18 years) diagnosed with de novo AML between 2019 and 2021 in nine Mexico City hospitals.

RESULTS

The overall frequency of the fusion genes was 50.7%; RUNX1-RUNXT1 (22.1%) and PML-RARA (20.8%) were the most prevalent, followed by CBFB-MYH11 (5.2%) and BCR-ABL1^p210 (2.4%). KMT2A-MLLT3 was not detected. Patients with PML-RARA showed the lowest survival with high early mortality events. However, more studies are required to evaluate the impact of analyzed fusion genes on the overall survival of the Mexican child population with AML.

CONCLUSION

The pediatric population of Mexico City with AML had frequencies of AML1-ETO, PML-RARA, CBFB-MYH11, and BCR-ABL1^p210 similar to those of other populations around the world. Patients with BCR-ABL1^p210 and CBFB-MYH11 were few or did not die, while those with MLL-AF9 was not detected. Although patients with PML-RARA had a low survival and a high early mortality rate, further studies are needed to determine the long-term impacts of these fusion genes on this Latino population.

Association Analysis Between the Functional Single Nucleotide Variants in miR-146a, miR-196a-2, miR-499a, and miR-612 With Acute Lymphoblastic Leukemia

Background

Acute lymphoblastic leukemia (ALL) is characterized by an abnormal proliferation of immature lymphocytes, in whose development involves both environmental and genetic factors. It is well known that single nucleotide polymorphisms (SNPs) in coding and noncoding genes contribute to the susceptibility to ALL. This study aims to determine whether SNPs in miR-146a, miR-196a-2, miR-499a, and miR-612 genes are associated with the risk to ALL in pediatric Mexican population.

Methods

A multicenter case-control study was carried out including patients with de novo diagnosis of ALL and healthy subjects as control group. The DNA samples were obtained from saliva and peripheral blood, and the genotyping of rs2910164, rs12803915, rs11614913, and rs3746444 was performed using the 5′exonuclease technique. Gene-gene interaction was evaluated by the multifactor dimensionality reduction (MDR) software.

Results

miR-499a rs3746444 showed significant differences among cases and controls. The rs3746444G allele was found as a risk factor to ALL (OR, 1.6 [95% CI, 1.05–2.5]; p = 0.028). The homozygous GG genotype of rs3746444 confers higher risk to ALL than the AA genotype (OR, 5.3 [95% CI, 1.23–23.4]; p = 0.01). Moreover, GG genotype highly increases the risk to ALL in male group (OR, 17.6 [95% CI, 1.04–298.9]; p = 0.00393). In addition, an association in a gender-dependent manner among SNPs located in miR-146a and miR-196a-2 genes and ALL susceptibility was found.

Conclusion

Our findings suggest that SNP located in miR-499a, miR-146a, and miR-196a-2 genes confer risk to ALL in Mexican children. Experimental analysis to decipher the role of these SNPs in human hematopoiesis could improve our understanding of the molecular mechanism underlying the development of ALL.

Citrulline supplementation improves spatial memory in a murine model for Alzheimer's disease

OBJECTIVES

Alzheimer's disease (AD) correlates with the dysfunction of metabolic pathways that translates into neurological symptoms. An arginine deficiency, a precursor of nitric oxide (NO), has been reported for patients with AD. We aimed to evaluate the effect of citrulline oral supplementation on cognitive decline in an AD murine model.

METHODS

Three-month citrulline or water supplementation was blindly given to male and female wild-type and 3 × Tg mice with AD trained and tested in the Morris water maze. Cerebrospinal fluid and brain tissue were collected. Ultra-performance liquid chromatography was used for arginine determinations and the Griess method for NO.

RESULTS

Eight-month-old male 3 × Tg mice with AD supplemented with citrulline performed significantly better in the Morris water maze task. Arginine levels increased in the cerebrospinal fluid although no changes were seen in brain tissue and only a tendency of increase of NO was observed.

CONCLUSIONS

Citrulline oral administration is a viable treatment for memory improvement in the early stages of AD, pointing to NO as a viable, efficient target for memory dysfunction in AD.

Copy Number Alterations are Associated with the Risk of Very Early Relapse in Pediatric B-lineage Acute Lymphoblastic Leukemia: A Nested Case-control MIGICCL Study

BACKGROUND

Refining risk stratification to avoid very early relapses (VER) in Mexican patients with B-lineage acute lymphoblastic leukemia (B-ALL) could lead to better survival rates in our population.

AIM OF THE STUDY

The purpose of this study was to investigate the association between the United Kingdom ALL (UKALL)-CNA classifier and VER risk in Mexican patients with childhood B-ALL.

METHODS

A nested case-control study of 25 cases with VER and 38 frequency-matched controls without relapse was conducted within the MIGICCL study cohort. They were grouped into the categories of the UKALL-CNA risk classifier (good [reference], intermediate and poor), according to the results obtained by multiplex ligation dependent probe amplification. Overall and disease-free survival (DFS) were estimated using the Kaplan-Meier method. Univariate and multivariate Cox proportional hazards analyses were conducted.

RESULTS

The CDKN2A/B genes were most frequently deleted in the group with relapse. According to UKALL-CNA classifier, 33 (52.4%) patients were classified as good, 21 (33.3%) intermediate and 9 (14.3%) poor-risk B-ALL. The intermediate and poor risk groups were associated with an increased risk of VER (HR = 4.94, 95% CI = 1.87-13.07 and HR = 7.42, 95% CI = 2.37-23.26, respectively) in comparison to the good-risk patients. After adjusting by NCI risk classification and chemotherapy scheme in a multivariate model, the risks remained significant.

CONCLUSIONS

Our data support the clinical utility of profiling CNAs to potentially refine current risk stratification strategies of patients with B-ALL.

Promising genes and variants to reduce chemotherapy adverse effects in acute lymphoblastic leukemia

Almost two decades ago, the sequencing of the human genome and high throughput technologies came to revolutionize the clinical and therapeutic approaches of patients with complex human diseases. In acute lymphoblastic leukemia (ALL), the most frequent childhood malignancy, these technologies have enabled to characterize the genomic landscape of the disease and have significantly improved the survival rates of ALL patients. Despite this, adverse reactions from treatment such as toxicity, drug resistance and secondary tumors formation are still serious consequences of chemotherapy, and the main obstacles to reduce ALL-related mortality. It is well known that germline variants and somatic mutations in genes involved in drug metabolism impact the efficacy of drugs used in oncohematological diseases therapy. So far, a broader spectrum of clinically actionable alterations that seems to be crucial for the progression and treatment response have been identified. Although these results are promising, it is necessary to put this knowledge into the clinics to help physician make medical decisions and generate an impact in patients' health. This review summarizes the gene variants and clinically actionable mutations that modify the efficacy of antileukemic drugs. Therefore, knowing their genetic status before treatment is critical to reduce severe adverse effects, toxicities and life-threatening consequences in ALL patients.

Prognostic Impact of Somatic Copy Number Alterations in Childhood B-Lineage Acute Lymphoblastic Leukemia

PURPOSE OF REVIEW

The high prevalence of relapse in pediatric B-lineage acute lymphoblastic leukemia (B-ALL) despite the improvements achieved using current risk stratification schemes, demands more accurate methods for outcome prediction. Here, we provide a concise overview about the key advances that have expanded our knowledge regarding the somatic defects across B-ALL genomes, particularly focusing on copy number alterations (CNAs) and their prognostic impact.

RECENT FINDINGS

The identification of commonly altered genes in B-ALL has inspired the development of risk classifiers based on copy number states such as the IKZF1^plus and the United Kingdom (UK) ALL-CNA classifiers to improve outcome prediction in B-ALL. CNA-risk classifiers have emerged as effective tools to predict disease relapse; though, their clinical applications are yet to be transferred to routine practice.

Genotype-Environment Interaction Analysis of NQO1, CYP2E1, and NAT2 Polymorphisms and the Risk of Childhood Acute Lymphoblastic Leukemia: A Report From the Mexican Interinstitutional Group for the Identification of the Causes of Childhood Leukemia

Background: Acute lymphoblastic leukemia (ALL) is the main type of cancer in children. In Mexico and other Hispanic populations, the incidence of this neoplasm is one of the highest reported worldwide. Functional polymorphisms of various enzymes involved in the metabolism of xenobiotics have been associated with an increased risk of developing ALL, and the risk is different by ethnicity. The aims of the present study were to identify whether NQO1, CYP2E1, and NAT2 polymorphisms or some genotype-environmental interactions were associated with ALL risk in Mexican children.

Methods: We conducted a case-control study including 478 pediatric patients diagnosed with ALL and 284 controls (children without leukemia). Ancestry composition of a subset of cases and controls was assessed using 32 ancestry informative markers. Genetic-environmental interactions for the exposure to hydrocarbons were assessed by logistic regression analysis.

Results: The polymorphisms rs1801280 (OR 1.54, 95% CI 1.21–1.93), rs1799929 (OR 1.96, 95% CI 1.55–2.49), and rs1208 (OR 1.44, 95% CI 1.14–1.81) were found to increase the risk of ALL; being the risks higher under a recessive model (OR 2.20, 95% CI 1.30–1.71, OR 3.87, 95% CI 2.20–6.80, and OR 2.26, 95% CI 1.32–3.87, respectively). Gene-environment interaction analysis showed that NAT2 rs1799929 TT genotype confers high risk to ALL under exposure to fertilizers, insecticides, hydrocarbon derivatives, and parental tobacco smoking. No associations among NQO1, CYP2E1, and ALL were observed.

Conclusion: Our study provides evidence for the association between NAT2 polymorphisms/gene-environment interactions, and the risk of childhood ALL in Mexican children.

[COVID-19 in pediatric cancer patients: risk of infection, surveillance and containment]

Coronavirus disease 2019 (COVID-19) continues to affect people throughout the planet due to its high contagion rate. Patients affected by the disease who received immunosuppressive treatments are at risk of developing the most serious aspects of COVID-19. So how does this new coronavirus affect pediatric cancer patients who are constantly immunosuppressed? How is it possible to reduce the risk of contagion in the oncology and hematology departments? We synthesized a couple of important articles on the subject.

Maternal and paternal ages at conception of index child and risk of childhood acute leukaemia: A multicentre case-control study in Greater Mexico City

BACKGROUND

The parental age at conception has been reported to be a risk factor for childhood acute leukaemia (AL); however, the relationship is controversial. The aim of the present study was to investigate the association between parental age at conception and the risk of AL in Mexican children, a population with a high incidence of the disease and a high prevalence of pregnancies in adolescents and young adults.

METHODS

A multicentre case-control study was conducted. Incident AL cases younger than 17 years of age diagnosed between 2010 and 2015 were included. Controls were matched with cases according to age, sex, and health institution. Using logistic regression analysis, adjusted odds ratios (aOR) and 95 % confidence intervals (95 % CI) were calculated for each maternal stratum after adjusting for paternal age at conception of index child. The maternal age between 25 and 29.99 years was selected as the reference category.

RESULTS

In most strata where maternal and paternal ages were assessed, no association was found with the risk of developing acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML) in their offspring. An increased risk for AML was observed when the mother was between 20 and 24.99 years of age and the father aged 25-29.99 years (aOR, 1.94; 95 % CI, 1.03-3.67). In addition, there was a positive association for ALL when the mother´s age was between 20 and 24.99 years and the father was <20 years of age, however, a very wide confidence interval was noted (aOR, 12.26; 95 % CI, 1.41-106.83).

CONCLUSION

In the present study, maternal and paternal ages assessed in different strata showed little association with risk of developing ALL and AML in children. Positive associations between risk of both types of childhood AL were observed with younger paternal and maternal ages.

Transcriptome Analysis Identifies LINC00152 as a Biomarker of Early Relapse and Mortality in Acute Lymphoblastic Leukemia

Evidence showing the role of long non-coding RNAs (lncRNAs) in leukemogenesis have emerged in the last decade. It has been proposed that these genes can be used as diagnosis and/or prognosis biomarkers in childhood acute lymphoblastic leukemia (ALL). To know if lncRNAs are associated with early relapse and early mortality, a microarray-based gene expression analysis in children with B-lineage ALL (B-ALL) was conducted. Cox regression analyses were performed. Hazard ratios (HR) and 95% confidence intervals (95% CI) were calculated. LINC00152 and LINC01013 were among the most differentially expressed genes in patients with early relapse and early mortality. For LINC00152 high expression, the risks of relapse and death were HR: 4.16 (95% CI: 1.46–11.86) and HR: 1.99 (95% CI: 0.66–6.02), respectively; for LINC01013 low expression, the risks of relapse and death were HR: 3.03 (95% CI: 1.14–8.05) and HR: 6.87 (95% CI: 1.50–31.48), respectively. These results were adjusted by NCI risk criteria and chemotherapy regimen. The lncRNA–mRNA co-expression analysis showed that LINC00152 potentially regulates genes involved in cell substrate adhesion and peptidyl–tyrosine autophosphorylation biological processes. The results of the present study point out that LINC00152 could be a potential biomarker of relapse in children with B-ALL.

Functional characterization of NK cells in Mexican pediatric patients with acute lymphoblastic leukemia: Report from the Mexican Interinstitutional Group for the Identification of the Causes of Childhood Leukemia

Acute lymphoblastic leukemia (ALL) is the most common cancer in children around the globe. Mexico City has one of the highest incidence rates of childhood leukemia worldwide with 49.5 cases per million children under the age of 15 which is similar to that reported for Hispanic populations living in the United States. In addition, it has been noted a dismal prognosis in Mexican and Hispanic ALL pediatric population. Although ALL, like cancer in general, has its origins in endogenous, exogenous, and genetic factors, several studies have shown that the immune system also plays a deterministic role in cancer development. Among various elements of the immune system, T lymphocytes and NK cells seem to dominate the immune response against leukemia. The aim of the present study was to perform a phenotypic and functional characterization of NK cells in ALL Mexican children at the moment of diagnosis and before treatment initiation. A case-control study was conducted by the Mexican Interinstitutional Group for the Identification of the Causes of Childhood Leukemia (MIGICCL). 41 cases were incident ALL children younger than 17 years old and residents of Mexico City. 14 controls were children without leukemia, matched by age and sex with cases. NK cell function was evaluated by degranulation assays towards K562 cells and SLAM-associated protein (SAP) expression was measured by intracellular staining. All assays were performed using peripheral blood mononuclear cells from controls and patients. The results indicate that NK mediated cytotoxicity, measured by CD107a degranulation assays in response to K562 cells, was reduced in ALL patients compared to controls. Interestingly, an impaired NK cell killing of target cells was not equally distributed among ALL patients. In contrast to patients classified as high-risk, standard-risk patients did not display a significant reduction in NK cell-mediated cytotoxicity. Moreover, patients presenting a leukocyte count ≥ 50,000xmm³ displayed a reduction in NK-cell mediated cytotoxicity and a reduction in SAP expression, indicating a positive correlation between a reduced SAP expression and an impaired NK cell-mediated citotoxicity. In the present study it was observed that unlike patients with standard-risk, NK cells from children presenting high-risk ALL, harbor an impaired cytotoxicity towards K562 at diagnosis. In addition, NK cell function was observed to be compromised in patients with a leukocyte count ≥50,000xmm³, where also it was noticed a decreased expression of SAP compared to patients with a leukocyte count <50,000xmm³. These data indicate NK cell-mediated cytotoxicity is not equally affected in ALL patients, nevertheless a positive correlation between low SAP expression and decreased NK cell-mediated cytotoxicity was observed in ALL patients with a leukocyte count ≥50,000xmm³. Finally, an abnormal NK cell-mediated cytotoxicity may represent a prognostic factor for high-risk acute lymphoblastic leukemia.

Overweight and obesity as predictors of early mortality in Mexican children with acute lymphoblastic leukemia: a multicenter cohort study

BACKGROUND

Mexico City has one of the highest incidences and mortality rates of acute lymphoblastic leukemia (ALL) in the world and a high frequency of early relapses (17%) and early mortality (15%). Otherwise, childhood overweight and obesity are reaching epidemic proportions. They have been associated with poor outcomes in children with ALL. The aim of present study was to identify if overweight and obesity are predictors of early mortality and relapse in Mexican children with ALL.

METHODS

A multicenter cohort study was conducted. ALL children younger than 15 years old were included and followed-up during the first 24 months after diagnosis. Overweight and obesity were classified according World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC) criteria. Early mortality and early relapses were the main outcomes.

RESULTS

A total of 1070 children were analyzed. Overweight/obesity at diagnosis were predictors of early mortality (WHO: HR = 1.4, 95%CI:1.0-2.0; CDC: HR = 1.6, 95%CI:1.1-2.3). However, no associations between overweight (WHO: HR = 1.5, 95%CI:0.9-2.5; CDC: HR = 1.0; 95% CI:0.6-1.6) and obesity (WHO: HR = 1.5, 95%CI:0.7-3.2; CDC: HR = 1.4; 95%CI:0.9-2.3) with early relapse were observed.

CONCLUSIONS

Overweight and obese patients embody a subgroup with high risk of dying during leukemia treatment.

Identification and Characterization of Novel Fusion Genes with Potential Clinical Applications in Mexican Children with Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia is the most common type of childhood cancer worldwide. Mexico City has one of the highest incidences and mortality rates of this cancer. It has previously been recognized that chromosomal translocations are important in cancer etiology. Specific fusion genes have been considered as important treatment targets in childhood acute lymphoblastic leukemia (ALL). The present research aimed at the identification and characterization of novel fusion genes with potential clinical implications in Mexican children with acute lymphoblastic leukemia. The RNA-sequencing approach was used. Four fusion genes not previously reported were identified: CREBBP-SRGAP2B, DNAH14-IKZF1, ETV6-SNUPN, ETV6-NUFIP1. Although a fusion gene is not sufficient to cause leukemia, it could be involved in the pathogenesis of the disease. Notably, these new translocations were found in genes encoding for hematopoietic transcription factors which are known to play an important role in leukemogenesis and disease prognosis such as IKZF1, CREBBP, and ETV6. In addition, they may have an impact on the prognosis of Mexican pediatric patients with ALL, with the potential to be included in the current risk stratification schemes or used as therapeutic targets.

Role of Epstein-Barr Virus in Glioblastoma

Gliomas are the most common and most lethal primary malignant adult brain tumors, and glioblastomas are the most frequent. Several risk factors are involved in their pathogenesis; these include environmental factors as well as host factors. The etiology of most gliomas remains unknown. Epstein-Barr Virus (EBV), a member of the Herpesviridae family, was the first tumoral virus to be described, and several viruses in connection with cancer were discovered thereafter. During the complex interaction between host and EBV, several events take place. In the context of survival, EBV can drive its host cells with subsequent disruption of the cellular machinery, leading to tumorigenesis as the final outcome. Thus, the EBV infection has been associated with different tumors. In this review, we discuss EBV and cancer. We have analyzed previously published papers and have conducted a critical analysis on the role of the viral infection in glioblastoma. Several works have described the presence of the virus, but none have shown a conclusive association. Thus, there is need to continue analyzing the interaction between host and virus to determine whether the viral presence is incidental or has some association with glioblastoma.

A greater birthweight increases the risk of acute leukemias in Mexican children-experience from the Mexican Interinstitutional Group for the Identification of the Causes of Childhood Leukemia (MIGICCL)

In Mexico, due to the high rates of diabetes, overweight, and obesity, there has also been noted an increased newborn weight, which may be contributing to the elevated incidence rate of childhood acute leukemia (AL). We conducted a case-control study in public hospitals of Mexico City aimed to know whether a greater weight at birth is associated with a higher risk of developing leukemia. We included incident cases with acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) diagnosed between 2010 and 2015. Controls were frequency-matched to the cases by age, sex, and health institution. Logistic regression analysis was performed adjusting risks by child's sex, overcrowding index, birth order, and mother's age at the time of pregnancy. Adjusted odds ratios (aORs) and 95% confidence intervals were calculated. A total of 1455 cases and 1455 controls were included. An evident association between ALL and child's birthweight ≥2500 g was found (aOR 2.06; 95% CI: 1.59, 2.66) and also, in those with birthweight ≥3500 g (aOR 1.19; 95% CI: 1.00, 1.41). In AML patients with birthweight ≥2500 g and ≥3500 g, an aOR of 1.77 (95% CI: 1.07, 2.94) and 1.42 (95% CI: 1.03-1.95) was observed, respectively. No association was noticed with either type of AL and a birthweight ≥4000 g. To sum up, we found a moderate association between not having a low birthweight and an increased risk of acute leukemias. Birthweight ≥3500 g was also a risk factor for both types of leukemia. This suggests that a greater birthweight may increase the risk of acute leukemias in Mexican children.

Infectious Agents in Childhood Leukemia

Acute leukemia is the most common pediatric cancer, representing one-third of all cancers that occurs in under 15 year olds, with a varied incidence worldwide. Although a number of advances have increased the knowledge of leukemia pathophysiology, its etiology remains less well understood. The role of infectious agents, such as viruses, bacteria, or parasites, in the pathogenesis of leukemia has been discussed. To date, several cellular mechanisms involving infectious agents have been proposed to cause leukemia following infections. However, although leukemia can be triggered by contact with such agents, they can also be beneficial in developing immune stimulation and protection despite the risk of leukemic clones. In this review, we analyze the proposed hypotheses concerning how infectious agents may play a role in the origin and development of leukemia, as well as in a possible mechanism of protection following infections. We review reported clinical observations associated with vaccination or breastfeeding, that support hypotheses such as early life exposure and the resulting early immune stimulation that lead to protection.

ARID5B, CEBPE and PIP4K2A Germline Genetic Polymorphisms and Risk of Childhood Acute Lymphoblastic Leukemia in Mexican Patients: A MIGICCL Study

BACKGROUND AND AIMS

Childhood acute lymphoblastic leukemia (ALL) is the leading cause of childhood cancer-related deaths worldwide. Multiples studies have shown that ALL seems to be originated by an interaction between environmental and genetic susceptibility factors. The ARID5B polymorphisms are among the most reproducible ALL associated-risk alleles in different populations. The aim of the present study was to examine the contribution of ARID5B, CEBPE, and PIP4K2 risk alleles for the development of ALL in children from Mexico City and Yucatan, Mexico.

METHODS

A study was conducted with a total of 761 unrelated subjects. Two hundred eighty five ALL cases (111 from Yucatan and 174 from Mexico City) and 476 healthy subjects. Genotyping included the rs7088318 (PIP4K2A), rs10821936 (ARID5B), rs7089424 (ARID5B) and rs2239633 (CEBPE) polymorphisms.

RESULTS

Associations between ALL and rs10821936 and rs7089424 ARID5B SNPs were found (OR = 1.9, 95% CI (1.5-2.4) and OR = 2.0, 95% CI (1.6-2.5), respectively). Moreover, a higher risk was observed in the homozygous risk genotypes of carriers from Mexico City (OR = 3.1, 95% CI (2.0-4.9) and OR 3.1, CI 95% (2.0-4.8), respectively). Otherwise, the rs7088318 (PIP4K2A) and rs2239633 (CEBPE) polymorphisms were not associated with ALL risk.

CONCLUSIONS

Our analysis suggests that ARID5B confers risk for childhood ALL in a Mexican population.

Gene Expression Profiling of Acute Lymphoblastic Leukemia in Children with Very Early Relapse

BACKGROUND AND AIMS

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer worldwide. Mexican patients have high mortality rates, low frequency of good prognosis biomarkers (i.e., ETV6-RUNX1) and a high proportion is classified at the time of diagnosis with a high risk to relapse according to clinical features. In addition, very early relapses are more frequently observed than in other populations. The aim of the study was to identify new potential biomarkers associated with very early relapse in Mexican ALL children through transcriptome analysis.

METHODS

Microarray gene expression profiling on bone marrow samples of 54 pediatric ALL patients, collected at time of diagnosis and/or at relapse, was performed. Eleven patients presented relapse within the first 18 months after diagnosis. Affymetrix Human Transcriptome Array 2.0 (HTA 2.0) was used to perform gene expression analysis. Annotation and functional enrichment analyses were carried out using Gene Ontology, KEGG pathway analysis and Ingenuity Pathway Analysis tools.

RESULTS

BLVRB, ZCCHC7, PAX5, EBF1, TMOD1 and BLNK were differentially expressed (fold-change >2.0 and p value <0.01) between relapsed and non-relapsed patients. Functional analysis of abnormally expressed genes revealed their important role in cellular processes related to the development of hematological diseases, cancer, cell death and survival and in cell-to-cell signaling interaction.

CONCLUSIONS

Our data support previous findings showing the relevance of PAX5, EBF1 and ZCCHC7 as potential biomarkers to identify a subgroup of ALL children in high risk to relapse.

Analysis of Thiopurine S-Methyltransferase Deficient Alleles in Acute Lymphoblastic Leukemia Patients in Mexican Patients

BACKGROUND AND AIMS

It has been demonstrated that heterozygote and homozygote thiopurine S-methyltransferase (TPMT) mutant allele carriers are at high risk to develop severe and potentially fatal hematopoietic toxicity after treatment with standard doses of 6-mercaptopurine (6-MP) and methotrexate (MX). Those drugs are the backbone of acute lymphoblastic leukemia (ALL) and several autoimmune disease treatments. We undertook this study to determine the frequency of the TPMT deficient alleles in children with ALL and non-ALL subjects from Mexico City and Yucatan, Mexico.

METHODS

We included 849 unrelated subjects, of which 368 ALL children and 342 non-ALL subjects were from Mexico City, and 60 ALL cases and 79 non-ALL individuals were from Yucatan. Genotyping of the rs1800462, rs1800460 and rs1142345 SNPs was performed by 5'exonuclease technique using TaqMan probes (Life Technologies Foster City, CA).

RESULTS

The mutant TPMT alleles were present in 4.8% (81/1698 chromosomes) and only 0.2% were homozygote TPMT*3A/TPMT*3A. We did not find statistically significant differences in the distribution of the mutant alleles between patients from Mexico City and Yucatan in either ALL cases or non-ALL. Nonetheless, the TPMT*3C frequency in ALL patients was higher than non-ALL subjects (p = 0.03). To note, the null homozygous TPMT*3A/TPMT*3A genotype was found in 2.5% of the non-ALL subjects.

CONCLUSIONS

TPMT mutant alleles did not exhibit differential distribution between both evaluated populations; however, TPMT*3C is overrepresented in ALL cases in comparison with non-ALL group. Assessing the TPMT mutant alleles could benefit the ALL children and those undergoing 6-MP and MX treatment.

Parental Exposure to Workplace Carcinogens and the Risk of Development of Acute Leukemia in Infants. Case-Control Study

BACKGROUND AND AIMS

Occupational exposure of parents to carcinogens is of great interest in the etiology of leukemias. Evidence of the impact of such exposure on infants or small children is scarce. Here we estimated whether occupational exposure of parents to carcinogens could be a risk factor for leukemias in their children.

METHODS

Cases of acute leukemia (AL) in infants ≤24 months old diagnosed in Mexico City (1998-2013) were included in a population-based, case-control study. Each of the 195 cases was matched with at least one healthy child (n = 369). For each of four exposure windows studied, the degree of exposure to carcinogens was determined for both parents by using a validated occupational exposure index. An unconditional logistic regression was carried out.

RESULTS

Odds ratios (OR) and the 95% confidence intervals (CI) of the overall occupational exposure for parents during the four exposure windows indicated no association with risk of AL in their children. Pre-conception, the OR by the father 0.77 (0.49-1.21), by the mother 1.03 (0.50-2.11); during pregnancy, father 0.66 (0.38-1.15), mother 1.79 (0.46-6.90); during breastfeeding, father 0.75 (0.43-1.30), mother 0.96 (0.21-4.30); and after birth, father 0.74 (0.45-1.22), mother 0.90 (0.24-3.32). The statistical power of the sample size to identify an OR ≥2 and an exposure of ≥10% among controls was 78%.

CONCLUSIONS

These data support the idea that parents' occupational exposure during any of the periods studied was not a risk factor contributing to the etiology of AL in infants ≤24 months of age.

Adipokines, insulin resistance, and adiposity as a predictors of metabolic syndrome in child survivors of lymphoma and acute lymphoblastic leukemia of a developing country

BACKGROUND

There is a growing body of evidence indicating that pediatric survivors of cancer are at a greater risk of developing metabolic syndrome. This study evaluated some probable predictors of metabolic syndrome (MS), such as leptin and adiponectin concentrations, the leptin/adiponectin ratio, insulin resistance, and adiposity, in a sample of child survivors of lymphoma and leukemia in Mexico City.

METHODS

Fifty two children (leukemia n = 26, lymphoma n = 26), who were within the first 5 years after cessation of therapy, were considered as eligible to participate in the study. Testing included fasting insulin, glucose, adipokines and lipids; body fat mass was measured by DXA. The MS components were analyzed according to tertiles of adipokines, insulin resistance, and adiposity. Comparisons between continuous variables were performed according to the data distribution. The MS components were analyzed according to tertiles of adipokines, insulin resistance, and adiposity. With the purpose of assessing the risk of a present MS diagnosis, odds ratios (OR) with a 95% confidence interval (95% IC) were obtained using logistic regression analysis according to the various metabolic markers.

RESULTS

The median children age was 12.1 years, and the interval time from the completion of therapy to study enrollment was 4 years. Among the MS components, the prevalence of HDL-C low was most common (42%), followed by central obesity (29%). The HOMA-IR (OR 9.0, 95% CI 2.0; 41.1), body fat (OR 5.5, 95% CI 1.6; 19.3), leptin level (OR 5.7, 95% CI 1.6; 20.2) and leptin/adiponectin ratio (OR 9.4, 95% CI 2.0; 49.8) in the highest tertile, were predictive factors of developing MS; whereas the lowest tertile of adiponectin was associated with a protective effect but not significant.

CONCLUSIONS

Biomarkers such as HOMA-IR, leptin and leptin/adiponectin are associated with each of the components of the MS and with a heightened risk of suffering MS among children survivors of cancer. Given the close relationship between MS with risk of developing type 2 diabetes and cardiovascular disease, it is imperative to implement prevention measures in this population and especially in developing countries where these pathologies have become the leading cause of death.

An overview of the infection of CMV, HSV 1/2 and EBV in Mexican patients with glioblastoma multiforme

Several risk factors are involved in glioblastoma, including cytomegalovirus (CMV). This research was carried out to determine the rate of CMV infection, as well as HSV 1/2 and EBV in brain tissue, in patients with glioblastomamultiforme (GBM). The tissues were tested using immunohistochemistry, PCR, in situ hybridization and real-time PCR. At least, one HHV was detected in 21/29 (72%) patients as follows: single infections with HSV-1/2 in 4/21 (19%), EBV in 6/21 (28.6%) and CMV in 1/21 (4.8%). Mixed viral infection, HSV-1/2 and EBV were detected in 4/21 patients (19%), CMV and EBV in 5/21 (23.8%), and HSV-1/2, EBV, and CMV in 1/21. The CMV viral load ranged from 3×10² to 4.33×10⁵ genome/100ng of tissue. Genotype based on CMV gB was 3/7 where 2/3 was gB1 and 1/3 gB4. HSV, EBV and CMV were frequently found in brain tissues, more in mix in a population reported as highly seropositive.

[Descriptive epidemiology of children with acute myeloid leukemia residing in Mexico City: a report from the Mexican Inter-Institutional Group for Identifying Childhood Leukemia Causes]

INTRODUCTION

Acute myeloid leukemias represent the second most common childhood leukemia subtype. In Mexico, there are few studies on descriptive epidemiology for this disease.

AIMS

To report acute myeloid leukemia incidence for children less than 15 years of age in the Metropolitan Area of the Valley of Mexico for a period of five years (2010-2014) and to analyze whether there are differences in the incidence of acute myeloid leukemia by regions.

MATERIAL AND METHODS

A descriptive study was conducted in nine public hospitals in Mexico City. The crude annual average incidence rate and adjusted average annual incidence rate were calculated.

RESULTS

A total of 190 patients with diagnosis of de novo acute myeloid leukemia were analyzed. Male sex (57.2%) and acute myeloid leukemia-M3 subtype (25.3%) were more frequent. The adjusted average annual incidence rates for Mexico City and for the Metropolitan Area of the Valley of Mexico were 8.18 and 7.74 per million children under 15 years old, respectively.

CONCLUSIONS

It seems that childhood acute myeloid leukemia incidence is increasing in Mexico City, which makes the identification of associated risk factors imperative.

Molecular epidemiology of acute leukemia in children: causal model, interaction of three factors-susceptibility, environmental exposure and vulnerability period

Acute leukemias have a huge morphological, cytogenetic and molecular heterogeneity and genetic polymorphisms associated with susceptibility. Every leukemia presents causal factors associated with the development of the disease. Particularly, when three factors are present, they result in the development of acute leukemia. These phenomena are susceptibility, environmental exposure and a period that, for this model, has been called the period of vulnerability. This framework shows how the concepts of molecular epidemiology have established a reference from which it is more feasible to identify the environmental factors associated with the development of leukemia in children. Subsequently, the arguments show that only susceptible children are likely to develop leukemia once exposed to an environmental factor. For additional exposure, if the child is not susceptible to leukemia, the disease does not develop. In addition, this exposure should occur during a time window when hematopoietic cells and their environment are more vulnerable to such interaction, causing the development of leukemia. This model seeks to predict the time when the leukemia develops and attempts to give a context in which the causality of childhood leukemia should be studied. This information can influence and reduce the risk of a child developing leukemia.

TNF, IL6, and IL1B Polymorphisms Are Associated with Severe Influenza A (H1N1) Virus Infection in the Mexican Population

Background

Hypercytokinemia is the main immunopathological mechanism contributing to a more severe clinical course in influenza A (H1N1) virus infections. Most patients infected with the influenza A (H1N1) pdm09 virus had increased systemic levels of pro-inflammatory cytokines; including interleukin IL-6, IL-8, and tumor necrosis factor-alpha (TNF-α). We propose that single-nucleotide polymorphisms (SNPs) in the promoter regions of pro-inflammatory genes are associated with the severity of influenza A (H1N1) pdm09 virus infection.

Methods

145 patients with influenza A (H1N1) (pA/H1N1), 133 patients with influenza-like illness (ILI), and 360 asymptomatic healthy contacts (AHCs) were included. Eleven SNPs were genotyped in six genes (TNF, LT, IL1B, IL6, CCL1, and IL8) using real-time PCR; the ancestral genotype was used for comparison. Genotypes were correlated with 27 clinical severity variables. Ten cytokines (GM-CSF, TNF-α, IL-2, IL-1β, IL-6, IL-8, IFN-γ, IL-10, IL-5, and IL-4) were measured on a Luminex 100.

Results

The IL6 rs1818879 (GA) heterozygous genotype was associated with severe influenza A (H1N1) virus infection (odds ratio [OR] = 5.94, 95% confidence interval [CI] 3.05–11.56), and two IL1B SNPs, rs16944 AG and rs3136558 TC, were associated with a decreased risk of infection (OR = 0.52 and OR = 0.51, respectively). Genetic susceptibility was determined (pA/H1N1 vs. AHC): the LTA rs909253 TC heterozygous genotype conferred greater risk (OR = 1.9), and a similar association was observed with the IL1B rs3136558 CC genotype (OR = 1.89). Additionally, severely ill patients were compared with moderately ill patients. The TNF-238 GA genotype was associated with an increased risk of disease severity (OR = 16.06, p = 0.007). Compared with ILIs, patients with severe pA/H1N1 infections exhibited increased serum IL-5 (p <0.001) and IL-6 (p  =  0.007) levels.

Conclusions

The TNF gene was associated with disease severity, whereas IL1B and IL6 SNPs were associated with influenza A (H1N1) virus infection.

[Bibliometric analysis of scientific output on influenza in Mexico, 2000-2012]

BACKGROUND

During the spring of 2009, H1N1 influenza became the first pandemic of the 21st century. There are no bibliometric studies in Mexico that have analyzed this topic in relation to the generation of Mexican knowledge. The aim of this article is to determine the volume and impact of Mexican scientific output published in journals indexed in Science Citation Index (SCI) on influenza from January 1, 2000, to October 1, 2012.

METHODS

All the documents within SCI whose topic was influenza were included; in order to do this, we used the describers influenza or swine flu H1N1. The analysis included authorship, international collaboration, journals, document type, citations and address of correspondence.

RESULTS

In 2000-2012, 241 articles related to influenza were published. The years with the highest number of articles were 2009 (n = 53) and 2010 (n = 62). The journals with the highest quantity of papers were Salud Pública de México (n = 16), PLOS ONE (n = 13), Archives of Medical Research (n = 13) and Vaccine (n = 10). The most investigated area was infectious diseases (18.9 %), followed by internal medicine (14 %) and immunology (14 %), occupational health (13 %) and experimental medicine (12.3 %).

CONCLUSION

The scientific output on influenza supposes near 1 % of the total of the medical-scientific production with a decline posterior to the outbreak of 2009 pandemic influenza.

[Molecular biology and childhood leukemia: E2A-PBX1 and central nervous system relapse]

Acute lymphoblastic leukemia (ALL) is the most common cancer in children. The inclusion of molecular biology techniques in the diagnosis and prognostic stratification of these patients has allowed major treatment achievements in developed countries. One of the best studied gene rearrangements is E2A-PBX1, which predicts isolated central nervous system relapse in patients with ALL. However, further research on the search for new molecular markers related to prognosis of patients with childhood leukemia is required. Such studies need the integration of different disciplines, including epidemiology. Epidemiological studies are needed not only to accelerate the discovery of new molecular markers and new biological signals as to the etiology and pathophysiology of cancer, but also to evaluate the clinical impact of these findings in well-defined populations.

[Adjuvant cryosurgery in the treatment of unicameral bone cysts]

BACKGROUND

Multiple treatments have been used for the unicameral bone cyst lesion, such as steroid application, multiple perforations, bone curettages, partial resection and bone grafting. The purpose of this study was to describe the evolution of children with unicameral bone cyst who were treated with cryosurgery as coadjuvant therapy.

METHODS

Cross-sectional descriptive study over the period between January 2001 and December 2006. Twelve patients were studied and treated at the Pediatric Orthopedics Department of the Pediatrics Hospital at the Centro Médico Nacional Siglo XXI.

RESULTS

Twelve patients were analyzed; all of them were treated with curettage, cryotherapy and bone grafting. In 7 patients, the lesions were located in the humerus (58.3 %), in 3 in the tibia (25 %), in 1 in the ilio-ischiopubic branch (8.3 %), and in 1 in the clavicle (8.3 %). Follow-up ranged from 12 to 36 months. Bone healing required 2 to 3 months after the surgery; the response was complete in 9 (75 %) patients and partial in 3 (25 %). Function was restored in all cases, without recurrences.

CONCLUSIONS

Cryosurgery as an adjuvant treatment and autologous or homologous bone grafting prevented local recurrence of unicameral bone cyst lesions, favored bone healing and allowed for a full range of motion functionality without complications.

[Learning styles in medical residents and their professors of a pediatric hospital.]

Background: the learning styles are cognitive, emotional, and psychological characteristics, which function as relatively stable indicators of how teachers and students perceive, interact, and respond to their learning environments. Knowing students' styles allows teachers to have tools to improve medical education. Our objective was to identify learning styles in pediatric residents and professors from a pediatric hospital. Methods: a learning styles questionnaire was applied to residents and theirs professors; data was analyzed in SPSS 12 software. Results: the dominant learning style in pediatric residents was reflexive and for professors was theoretical. There wasn't any difference between sexes or between medical or surgical specialities. There was more correlation between professors and residents when there was an increase in training time. Conclusions: the learning styles between professors and residents are different, especially at the beginning of the medical specialty courses; that's why it is necessary to realize a confrontation between the students' learning styles and teaching methods used by professors to improve significant learning. To know learning styles gives residents an important alternative to find a better study strategy.

Lack of evidence for human T-lymphotropic virus type 1 and mouse mammary tumor-like virus involvement in the genesis of childhood acute lymphoblastic leukemia

BACKGROUND

In Mexico City, the incidence of childhood acute lymphoblastic leukemia (ALL) is one of the highest in the world; epidemiologic evidence suggests that infectious agents could be involved in the genesis of this disease. Early transmitted oncogenic retroviruses infecting lymphocytes are important candidates.

METHODS

PCR-based assays were used to screen viral genomic sequences of human T-cell lymphotrophic virus, type 1 (HTLV1) and mouse mammary tumor virus (MMTV)-like virus (MMTV-LV) in leukemic cells from 67 pediatric patients with ALL.

RESULTS

Viral genomic sequences were not detected in any sample by neither standard nor nested PCR.

CONCLUSIONS

Because of the methodologic strictness and high statistical power of the study, these results suggest that HTLV1 and MMTV-LV are not involved in the genesis of childhood ALL in Mexican children.

IMPACT

To our knowledge, this is the first work exploring the direct participation of HTLV1 and MMTV-LV retroviruses in childhood ALL development.

[Guideline for the assessment of clinical research proposals. Comisión Nacional de Investigación Científica del Instituto Mexicano del Seguro Social]

BACKGROUND

Medical research is a fundamental tool to achieve the advancement of science, through the improvement of strategies aimed to protect, promote and restore an individual's and society's health. Three characteristics are required to obtain approval of the research proposal: scientific relevance, technical quality and the accomplishment of ethical issues.

OBJECTIVES

The present review aimed at the determination of the specific criteria to perform a critical review of research proposals.

METHODS

A research was carried out in the PubMed, Medline, Ovid and Google Scholar databases, using the terms: peer review, research proposals, review and protocols, and reviewers. A total of 3546 related articles were reviewed, without finding a guide to critically assess research proposals. The guides to assess research articles consider that the quality criteria of the study should have been present since the study's conception; many of the issues described to review articles are incorporated in the review of the research proposals.

RESULTS

The specific criteria were integrated to allow the reviewer to critically assess research proposals of different areas with scientific basis.

CONCLUSIONS

The reviewer of research proposals should be considered as a professional that contributes to the promotion of knowledge advancement through his/her comments, which allow researchers to improve the quality of research proposals.

Allergy and acute leukaemia in children with Down syndrome: a population study. Report from the Mexican inter-institutional group for the identification of the causes of childhood leukaemia

Background:

Allergies have been described as protective factors against the development of childhood acute leukaemia (AL). Our objective was to investigate the associations between allergy history and the development of AL and acute lymphoblastic leukaemia (ALL) in children with Down syndrome (DS).

Methods:

A case–control study was performed in Mexico City. The cases (n=97) were diagnosed at nine public hospitals, and the controls (n=222) were recruited at institutions for children with DS. Odds ratios (OR) were calculated.

Results:

Asthma was positively associated with AL development (OR=4.18; 95% confidence interval (CI): 1.47–11.87), whereas skin allergies were negatively associated (OR=0.42; 95% CI: 0.20–0.91).

Conclusion:

Our findings suggest that allergies and AL in children with DS share biological and immune mechanisms. To our knowledge, this is the first study reporting associations between allergies and AL in children with DS.

Pandemic influenza A/H1N1 virus infection and TNF, LTA, IL1B, IL6, IL8, and CCL polymorphisms in Mexican population: a case-control study

Background

Some patients have a greater response to viral infection than do others having a similar level of viral replication. Hypercytokinemia is the principal immunopathological mechanism that contributes to a severer clinical course in cases of influenza A/H1N1. The benefit produced, or damage caused, by these cytokines in severe disease is not known. The genes that code for these molecules are polymorphic and certain alleles have been associated with susceptibility to various diseases. The objective of the present study was to determine whether there was an association between polymorphisms of TNF, LTA, IL1B, IL6, IL8, and CCL1 and the infection and severity of the illness caused by the pandemic A/H1N1 in Mexico in 2009.

Methods

Case–control study. The cases were patients confirmed with real time PCR with infection by the A/H1N1 pandemic virus. The controls were patients with infection like to influenza and non-familial healthy contacts of the patients with influenza. Medical history and outcome of the disease was registered. The DNA samples were genotyped for polymorphisms TNF rs361525, rs1800629, and rs1800750; LTA rs909253; IL1B rs16944; IL6 rs1818879; IL8 rs4073; and CCL1 rs2282691. Odds ratio (OR) and the 95% confidence interval (95% CI) were calculated. The logistic regression model was adjusted by age and severity of the illness in cases.

Results

Infection with the pandemic A/H1N1 virus was associated with the following genotypes: TNF rs361525 AA, OR = 27.00; 95% CI = 3.07–1248.77); LTA rs909253 AG (OR = 4.33, 95% CI = 1.82–10.32); TNF rs1800750 AA (OR = 4.33, 95% CI = 1.48–12.64); additionally, LTA rs909253 AG showed a limited statistically significant association with mortality (p = 0.06, OR = 3.13). Carriers of the TNF rs1800629 GA genotype were associated with high levels of blood urea nitrogen (p = 0.05); those of the TNF rs1800750 AA genotype, with high levels of creatine phosphokinase (p=0.05). The IL1B rs16944 AA genotype was associated with an elevated number of leukocytes (p <0.001) and the IL8 rs4073 AA genotype, with a higher value for P_aO₂ mm Hg.

Conclusion

The polymorphisms of genes involved in the inflammatory process contributed to the severity of the clinical behavior of infection by the pandemic influenza A/H1N1 virus.