Psychiatric polygenic risk as a predictor of COVID-19 risk and severity: insight into the genetic overlap between schizophrenia and COVID-19

Despite the high contagion and mortality rates that have accompanied the coronavirus disease-19 (COVID-19) pandemic, the clinical presentation of the syndrome varies greatly from one individual to another. Potential host factors that accompany greater risk from COVID-19 have been sought and schizophrenia (SCZ) patients seem to present more severe COVID-19 than control counterparts, with certain gene expression similarities between psychiatric and COVID-19 patients reported. We used summary statistics from the last SCZ, bipolar disorder (BD), and depression (DEP) meta-analyses available on the Psychiatric Genomics Consortium webpage to calculate polygenic risk scores (PRSs) for a target sample of 11,977 COVID-19 cases and 5943 subjects with unknown COVID-19 status. Linkage disequilibrium score (LDSC) regression analysis was performed when positive associations were obtained from the PRS analysis. The SCZ PRS was a significant predictor in the case/control, symptomatic/asymptomatic, and hospitalization/no hospitalization analyses in the total and female samples; and of symptomatic/asymptomatic status in men. No significant associations were found for the BD or DEP PRS or in the LDSC regression analysis. SNP-based genetic risk for SCZ, but not for BD or DEP, may be associated with higher risk of SARS-CoV-2 infection and COVID-19 severity, especially among women; however, predictive accuracy barely exceeded chance level. We believe that the inclusion of sexual loci and rare variations in the analysis of genomic overlap between SCZ and COVID-19 will help to elucidate the genetic commonalities between these conditions.

Colorectal cancer. Genetic variants in BMP signaling pathway and ancestry in the Mexican population

INTRODUCTION

Genetic variants related to bone morphogenetic proteins (BMP2, BMP4, GREM1, SMAD7) signaling pathway have been associated with colorectal cancer, mainly in Caucasian populations.

OBJECTIVE

To describe the association of variants in members of the BMP signaling pathway in a Mexican population, characterized by its indigenous American and Caucasian ancestry.

METHODS

Genotyping of 1,000 colorectal cancer cases and 1,043 control individuals recruited in Mexico City, Monterrey, and Torreón was carried out using the Sequenom platform. Associations between colorectal cancer and variants were studied with univariate and multivariate analyses.

RESULTS

Variants rs4444235, rs12953717 and rs4939827 replicated the association with the neoplasm (p ≤ 0.05). Caucasian ancestry showed association with the tumor.

CONCLUSIONS

The study replicated the associations between colorectal cancer and SMAD7 and BMP4 variants, with an association being observed with the Caucasian component of the ethnic mix.

Prevalence of alcohol, tobacco, and illicit drugs consumption during teenage pregnancy: an observational, prospective, and cross-sectional study

BACKGROUND

Teenage pregnancy is a significant public health issue in Mexico; its prevalence oscillates around 20% of all pregnancies. Concurrently, alcohol, tobacco, and illicit drug use have become more common in this age group.

METHODS

To estimate the prevalence of substance exposure in a population of pregnant teenagers, we conducted a prospective, observational, and cross-sectional study. The protocol was approved by the institutional review board. On informed consent, we asked 420 consecutive pregnant youngsters cared for at the outpatient obstetric service of a tertiary public regional women's and children's hospital in Nuevo León, in northeast Mexico, to answer a previously validated questionnaire to estimate the prevalence of alcohol, tobacco, or illicit drugs use during pregnancy.

RESULTS

Of the 420 participants, 317 (75.5%) consumed at least one substance during pregnancy. Alcohol, either alone or in combination, was consumed by 300 (71.7%) participants. Tobacco was used by 117 (27.8%) participants, almost always in combination with other substances, while marijuana and other illicit drugs were consumed by 92 (21.9%) participants. Approximately one-fourth of the participants, 102 (24.1%) reported no substance use during pregnancy.

CONCLUSIONS

In this series, the reported prevalence of alcohol, tobacco, and illicit drugs consumption during pregnancy, explored with a validated instrument, is higher than that previously reported in our country. This fact offers a worrying picture of another set of factors adding to the burden of teenage pregnancy.

Unraveling Signatures of Local Adaptation among Indigenous Groups from Mexico

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

Impact of genetic polymorphisms related to innate immune response on respiratory syncytial virus infection in children

Respiratory syncytial virus (RSV) causes lower respiratory tract infections and bronchiolitis, mainly affecting children under 2 years of age and immunocompromised patients. Currently, there are no available vaccines or efficient pharmacological treatments against RSV. In recent years, tremendous efforts have been directed to understand the pathological mechanisms of the disease and generate a vaccine against RSV. Although RSV is highly infectious, not all the patients who get infected develop bronchiolitis and severe disease. Through various sequencing studies, single nucleotide polymorphisms (SNPs) have been discovered in diverse receptors, cytokines, and transcriptional regulators with crucial role in the activation of the innate immune response, which is implicated in the susceptibility to develop or protect from severe forms of the infection. In this review, we highlighted how variations in the key genes affect the development of innate immune response against RSV. This data would provide crucial information about the mechanisms of viral infection, and in the future, could help in generation of new strategies for vaccine development or generation of the pharmacological treatments.

Gravedad de COVID-19 atribuible a obesidad según IMC y CUN-BAE

Introducción

La obesidad es considerada un factor de riesgo en casos graves de la COVID-19, habiendo sido analizada mediante el índice de masa corporal (IMC), estimador que no correlaciona adecuadamente con el porcentaje de grasa corporal (GC). El objetivo de este estudio ha sido analizar la fracción atribuible poblacional a la GC en formas graves de COVID-19 atendiendo al IMC y al CUN-BAE.

Material y métodos

Estudio multicéntrico observacional de prevalencia. Se recogió información sociodemográfica, antecedentes personales, IMC y CUN-BAE, de casos positivos SARS-CoV-2, de las provincias de León y La Rioja. Mediante modelos de regresión logística se calcularon odds ratio con sus respectivos intervalos de confianza del 95% ajustando por edad y antecedentes personales, así como la fracción atribuible poblacional a la GC.

Resultados

Participaron 785 pacientes, 123 (15,7%) fueron graves. Se detectaron como factores de riesgo la edad, la obesidad (tanto por IMC como por CUN-BAE) y los antecedentes personales. Un 51,6% de casos graves podrían ser atribuidos a un exceso de IMC y un 61,4% a exceso de GC estimada según CUN-BAE, observándose una mayor infraestimación del riesgo en mujeres.

Conclusiones

El exceso de GC es un factor de riesgo para formas graves de la COVID-19 junto con la edad avanzada y la presencia de enfermedades cardiovasculares, respiratorias crónicas u oncohematológicas. El IMC infraestima el riesgo, especialmente en mujeres, siendo el CUN-BAE el predictor seleccionado por su mejor estimación del porcentaje de GC.

Population structure and relatedness estimates in a Mexican sample

Population stratification (PS) is a confounding factor in genome-wide association studies (GWASs) and also an interesting process itself. Latin American populations have mixed genetic ancestry, which may account for PS. We have analyzed the relatedness, by means of the identity-by-descent (IBD) estimations, in a sample of 1805 individuals and 1.006.703 autosomal mutations from a case-control study of colorectal cancer in Mexico. When using the recommended protocol for quality control assessment, 402 should have been removed due to relatedness. Our purpose was to analyze this value in the context of an admixed population. For that aim, we reanalyzed the sample using two software designed for admixed populations, obtaining estimates of 110 and 70 related individuals to remove. The results showed that the first estimation of relatedness was an effect of the higher Native American contribution in part of the data samples, being a confounding factor for IBD estimations. We conclude in the importance of considering PS and genetic ancestry in order to avoid spurious results, not only in GWAS but also in relatedness analysis.

Serological Test to Determine Exposure to SARS-CoV-2: ELISA Based on the Receptor-Binding Domain of the Spike Protein (S-RBDN318-V510) Expressed in Escherichia coli

Massive worldwide serological testing for SARS-CoV-2 is needed to determine the extent of virus exposure in a particular region, the ratio of symptomatic to asymptomatic infected persons, and the duration and extent of immunity after infection. To achieve this, the development and production of reliable and cost-effective SARS-CoV-2 antigens is critical. We report the bacterial production of the peptide S-RBDN318-V510, which contains the receptor-binding domain of the SARS-CoV-2 spike protein (region of 193 amino acid residues from asparagine-318 to valine-510) of the SARS-CoV-2 spike protein. We purified this peptide using a straightforward approach involving bacterial lysis, his-tag-mediated affinity chromatography, and imidazole-assisted refolding. The antigen performances of S-RBDN318-V510 and a commercial full-length spike protein were compared in ELISAs. In direct ELISAs, where the antigen was directly bound to the ELISA surface, both antigens discriminated sera from non-exposed and exposed individuals. However, the discriminating resolution was better in ELISAs that used the full-spike antigen than the S-RBDN318-V510. Attachment of the antigens to the ELISA surface using a layer of anti-histidine antibodies gave equivalent resolution for both S-RBDN318-V510 and the full-length spike protein. Results demonstrate that ELISA-functional SARS-CoV-2 antigens can be produced in bacterial cultures, and that S-RBDN318-V510 may represent a cost-effective alternative to the use of structurally more complex antigens in serological COVID-19 testing.

Differential admixture in Latin American populations and its impact on the study of colorectal cancer

Genome-wide association studies focused on searching genes responsible for several diseases. Admixture mapping studies proposed a more efficient alternative capable of detecting polymorphisms contributing with a small effect on the disease risk. This method focuses on the higher values of linkage disequilibrium in admixed populations. To test this, we analyzed 10 genomic regions previously defined as related with colorectal cancer among nine populations and studied the variation pattern of haplotypic structures and heterozygosity values on seven categories of SNPs. Both analyses showed differences among chromosomal regions and studied populations. Admixed Latin-American samples generally show intermediate values. Heterozygosity of the SNPs grouped in categories varies more in each gene than in each population. African related populations have more blocks per chromosomal region, coherently with their antiquity. In sum, some similarities were found among Latin American populations, but each chromosomal region showed a particular behavior, despite the fact that the study refers to genes and regions related with one particular complex disease. This study strongly suggests the necessity of developing statistical methods to deal with di- or tri-hybrid populations, as well as to carefully analyze the different historic and demographic scenarios, and the different characteristics of particular chromosomal regions and evolutionary forces.

The Tumor-on-Chip: Recent Advances in the Development of Microfluidic Systems to Recapitulate the Physiology of Solid Tumors

The ideal in vitro recreation of the micro-tumor niche-although much needed for a better understanding of cancer etiology and development of better anticancer therapies-is highly challenging. Tumors are complex three-dimensional (3D) tissues that establish a dynamic cross-talk with the surrounding tissues through complex chemical signaling. An extensive body of experimental evidence has established that 3D culture systems more closely recapitulate the architecture and the physiology of human solid tumors when compared with traditional 2D systems. Moreover, conventional 3D culture systems fail to recreate the dynamics of the tumor niche. Tumor-on-chip systems, which are microfluidic devices that aim to recreate relevant features of the tumor physiology, have recently emerged as powerful tools in cancer research. In tumor-on-chip systems, the use of microfluidics adds another dimension of physiological mimicry by allowing a continuous feed of nutrients (and pharmaceutical compounds). Here, we discuss recently published literature related to the culture of solid tumor-like tissues in microfluidic systems (tumor-on-chip devices). Our aim is to provide the readers with an overview of the state of the art on this particular theme and to illustrate the toolbox available today for engineering tumor-like structures (and their environments) in microfluidic devices. The suitability of tumor-on-chip devices is increasing in many areas of cancer research, including the study of the physiology of solid tumors, the screening of novel anticancer pharmaceutical compounds before resourcing to animal models, and the development of personalized treatments. In the years to come, additive manufacturing (3D bioprinting and 3D printing), computational fluid dynamics, and medium- to high-throughput omics will become powerful enablers of a new wave of more sophisticated and effective tumor-on-chip devices.

Comparison of specific expression profile in two in vitro hypoxia models

The microenvironment plays a fundamental role in carcinogenesis: Acidity and hypoxia are actively involved in this process. It is important to have in vitro models to study these mechanisms. The models that are most commonly referred to are the hypoxia chamber and the chemical induction [Cobalt (II) chloride]. It is not yet defined if these models are interchangeable if the metabolic effect is the same, and if the results may be compared in these models. In the present study, the response to the effect of stress (hypoxia and acidity) in both models was evaluated. The results indicated that in the chemical model, the effect of hypoxia appeared in an early form at 6 h; whereas in the gas chamber the effect was slow and gradual and at 72 h there was an overexpression of erythropoietin (EPO), vascular endothelial growth factor (VEGF), carbonic anhydrase 9 (CA9) and hypoxia-inducible factor 1α (HIF1α). In addition to the genes analyzed by reverse transcription-quantitative polymerase chain reaction, the global expression analysis between both models revealed the 9 most affected genes in common. The present study additionally identified 3 potential genes (lysyl oxidase, ankyrin repeat domain 37, B-cell lymphoma 2 interacting protein 3 like) previously identified in other studies, which may be considered as universal hypoxia genes along with HIF1α, EPO, VEGF, glucose transporter 1 (GLUT1), CA9, and LDH. To the best of the author's knowledge, this is the first time that both hypoxia models have been compared, and it was demonstrated that the effect of hypoxia induction was time sensitive in each model. These observations must be considered prior to selecting one of these models to identify selective hypoxia genes and their effects in cancer.

Abstract P2-08-04: HMGA1 negatively regulates the expression of PRRX1 in triple negative breast cancer cells, which favors the progression to metastasis

Background: Triple negative breast cancer (TNBC) presents a very aggressive behavior with a high rate of metastasis. Overexpression of HMGA1 has been reported in TNBC and has been associated with the induction of the Epithelial-Mesenchymal transition (EMT) and metastasis. Therefore, HMGA1 is considered a master regulator of tumor progression in TNBC. The objective of this work was to know which genes are directly or indirectly regulated by HMGA1 to better understand their participation in EMT and their role in aggressive TNBC.

Methods: We performed the silencing of the HMGA1 gene using siRNA Silencer® Select Pre-designed (s6667 HMGA1, 4390849 GAPDH, 4390843 Negative control, all from Thermo Fisher, MA, USA) in two TNBC cell lines, HCC-1395 and MDA-MB-231, and we observed the effect of this gene inhibition by microarray global expression analysis using GeneChip Human Genome U133 Plus 2.0 (Affymetrix, CA, USA), comparing the conditions of inhibition versus their own control without inhibition. After the microarray data mining, results for the HMGA1 and PRRX1 genes were validated by qPCR using the Prime Time® Primers for HMGA1 (Hs.PT.58.38699366), PRRX1 (Hs.PT.58.2820749), and GAPDH as endogenous gene (Hs.PT.39a.22214836) with SybrGreen reagent (Roche, Basel, Switzerland). The level of expression of the HMGA1 and PRRX1 proteins was analyzed by Western blot in nuclear protein extracts of each cell line before and after gene silencing. Finally, we performed an in silico analysis using the "Gene 2 promoter" tool in the Genomatix platform to search the promoters and binding proteins of the PRRX1 gene.

Results: The silencing of HMGA1 in a non-metastatic TNBC-cell line, HCC-1395, showed deregulation of genes associated with cell proliferation and angiogenesis. Meanwhile the silencing in a TNBC-metastatic cell line, MDA-MB-231, resulted in the deregulation of genes involved in the formation and organization of the cytoskeleton, including the overexpression of PRRX1. Validation of the expression changes of HMGA1 and PRRX1 by qPCR and Western blot was performed and HMGA1 was confirmed to negatively regulate the PRRX1 gene expression. Through in silico studies, we identified several binding sites of HMGA1 to the PRRX1 promoter.

Conclusions: The subexpression of PRRX1 is necessary for EMT to occur. In this study, we present the interesting finding that HMGA1 regulates the subexpression of PRRX1, as supported by the experiments of transcriptional and translational expression presented in this work. To our knowledge, this is the first report describing a regulatory role of HMGA1 on PRRX1, which could explain the metastatic capacity of cancers that overexpress HMGA1.

Key words: Epithelial-Mesenchymal Transition, Triple Negative Breast Cancer, Mesenchymal-Epithelial Transition, Metastasis.

Citation Format: Aguayo-Millán CD, Santuario-Facio SK, Treviño-Alvarado V, Calvo-Anguiano G, Rojas-Martínez A, Camacho-Morales A, Ortíz-López R. HMGA1 negatively regulates the expression of PRRX1 in triple negative breast cancer cells, which favors the progression to metastasis [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-08-04.

Immunotherapy and gene therapy as novel treatments for cancer

The immune system interacts closely with tumors during the disease development and progression to metastasis. The complex communication between the immune system and the tumor cells can prevent or promote tumor growth. New therapeutic approaches harnessing protective immunological mechanisms have recently shown very promising results. This is performed by blocking inhibitory signals or by activating immunological effector cells directly. Immune checkpoint blockade with monoclonal antibodies directed against the inhibitory immune receptors CTLA-4 and PD-1 has emerged as a successful treatment approach for patients with advanced melanoma. Ipilimumab is an anti-CTLA-4 antibody which demonstrated good results when administered to patients with melanoma. Gene therapy has also shown promising results in clinical trials. Particularly, Herpes simplex virus (HSV)-mediated delivery of the HSV thymidine kinase (TK) gene to tumor cells in combination with ganciclovir (GCV) may provide an effective suicide gene therapy for destruction of glioblastomas, prostate tumors and other neoplasias by recruiting tumor-infiltrating lymphocytes into the tumor. The development of new treatment strategies or combination of available innovative therapies to improve cell cytotoxic T lymphocytes trafficking into the tumor mass and the production of inhibitory molecules blocking tumor tissue immune-tolerance are crucial to improve the efficacy of cancer therapy.

Prevalence and 3-year persistence of human papillomavirus serotypes in asymptomatic patients in Northern Mexico

OBJECTIVE

To investigate clinical outcomes and 3-year persistence of human papillomavirus (HPV) infections among women in Mexico.

METHODS

A prospective study enrolled sexually active women attending primary healthcare clinics in metropolitan Monterrey, Mexico, between June 3 and August 30, 2002. Baseline data were collected and participants underwent HPV screening. Patients with HPV infections were asked to attend a repeat screening appointment after 3 years, when the same screening data were gathered. Descriptive analyses were performed and the prevalence of cervical lesions and viral infections were examined.

RESULTS

In total, 1188 patients who underwent initial HPV screening were included. Cervical lesions were detected in 5 (0.4%) patients and 239 (20.1%) patients had HPV infections; 129 (54.0%) of these patients attended 3-year follow-up. Among the 357 HPV serotypes identified, the most prevalent serotypes were HPV-59, HPV-52, HPV-16, and HPV-56, detected 62 (17.4%), 38 (10.6%), 27 (7.6%), and 18 (5.0%) times, respectively. Of the 129 patients attending 3-year follow-up, 104 (80.6%) were clear from HPV infections, 13 (10.1%) patients had persistent HPV infections, and 12 (9.3%) had HPV infections with different HPV types.

CONCLUSIONS

The HPV prevalence was 20.1% in the present study; the most prevalent infections were HPV-59, HPV-52, HPV-16, and HPV-56. At 3-year follow-up, 25 (19.4%) patients had HPV infections.

Preclinical trial on the use of doxycycline for the treatment of adenocarcinoma of the duodenum

Adenocarcinoma of the duodenum comprises 50-70% of duodenal tumors. There is an increase in extracellular matrix metalloproteinases in this disease and it has been suggested that they play an important role in the development and pathology. Therefore, new therapeutic recommendations based on inhibitors of these enzymes, such as doxycycline, are under investigation. The cytotoxic effect of doxycycline was evaluated in the HuTu-80 duodenal adenocarcinoma cell line and its antitumor effect was determined in an immunodeficient murine model. A 10-µM (4.4 µg/ml) concentration of doxycycline was capable of causing apoptosis in 90% of the culture cells. Doxycycline was also responsible for a decrease in tumor growth and an increase in the survival of the mice with HuTu-80-cell tumors. These results suggest that doxycycline is a potential cytotoxic and antitumor agent effective in the treatment of adenocarcinoma of the duodenum.

[Association between genotype and allele frequencies of CYP2A6*12 and rs16969968 in CHRNA5 variants with smoking and body mass index in young subjects from Northeast Mexico]

BACKGROUND

Several studies have reported that variants rs16969968 G>A of the CHRNA5 gene and CYP2A6*12 of the CYP2A6 gene are associated with smoking and smoking refusal, respectively. In addition, some studies report that a higher cigarette consumption is associated with low body mass index (BMI).

AIM

To analyze the allele and genotypic frequencies of these variants and their impact on smoking and BMI.

MATERIAL AND METHODS

A blood sample was obtained and a survey about smoking habits was answered by 319 university students aged 18 to 35 years (127 women, 171 smokers), living in Northeastern Mexico. Genetic variants were studied by polymerase chain reaction/restriction fragment length polymorphism and their frequencies were associated with smoking and BMI.

RESULTS

No associations were found between the analyzed variants and smoking in the study groups. However, there was an association among non-smoking subjects between the A allele of rs16969968 and high a BMI (p < 0.01).

CONCLUSIONS

This last variant may be involved in food-addiction disorders.

Ionizing radiation-induced DNA injury and damage detection in patients with breast cancer

Breast cancer is the most common malignancy in women. Radiotherapy is frequently used in patients with breast cancer, but some patients may be more susceptible to ionizing radiation, and increased exposure to radiation sources may be associated to radiation adverse events. This susceptibility may be related to deficiencies in DNA repair mechanisms that are activated after cell-radiation, which causes DNA damage, particularly DNA double strand breaks. Some of these genetic susceptibilities in DNA-repair mechanisms are implicated in the etiology of hereditary breast/ovarian cancer (pathologic mutations in the BRCA 1 and 2 genes), but other less penetrant variants in genes involved in sporadic breast cancer have been described. These same genetic susceptibilities may be involved in negative radiotherapeutic outcomes. For these reasons, it is necessary to implement methods for detecting patients who are susceptible to radiotherapy-related adverse events. This review discusses mechanisms of DNA damage and repair, genes related to these functions, and the diagnosis methods designed and under research for detection of breast cancer patients with increased radiosensitivity.

Human papillomavirus type 2 associated with pyogenic granuloma in patients without clinical evidence of warts

BACKGROUND

Pyogenic granuloma is a non-neoplastic lesion that frequently occurs in the skin and mucous membranes of children and pregnant women. The anatomical sites of pyogenic granulomas overlap with those of wart infections caused by the human papillomavirus (HPV).

OBJECTIVE

This study assessed the presence of HPV DNA in pyogenic granuloma samples by polymerase chain reaction.

METHODS

Eighteen pyogenic granuloma biopsies from patients without a clinical history or evidence of verruca in the studied area were tested for the presence of the HPV genome. The presence of HPV DNA was screened by three independent polymerase chain reaction reactions using standard consensus primer sets targeted to the L1 or E1 consensus regions of HPV genome. The HPV DNA-positive samples were genotyped using methodologies enabling the identification of up to 30 HPVs, including oncogenic, nononcogenic, and cutaneous viral types.

RESULTS

The HPV DNA was detected in 44.4% (eight of 18) of the samples, with HPV-2 being the only type in the eight HPV DNA-positive samples. Contamination with HPV-2 sequences throughout the entire process was reliably eliminated.

CONCLUSION

This report is the first to suggest an association between HPV-2 and pyogenic granuloma. This relationship is similar to that observed between HPV-2 and nongenital warts.

Differential Expression of Adhesion-Related Proteins and MAPK Pathways Lead to Suitable Osteoblast Differentiation of Human Mesenchymal Stem Cells Subpopulations

Cellular adhesion enables communication between cells and their environment. Adhesion can be achieved throughout focal adhesions and its components influence osteoblast differentiation of human mesenchymal stem cells (hMSCs). Because cell adhesion and osteoblast differentiation are closely related, this article aimed to analyze the expression profiles of adhesion-related proteins during osteoblastic differentiation of two hMSCs subpopulations (CD105(+) and CD105(-)) and propose a strategy for assembling bone grafts based on its adhesion ability. In vitro experiments of osteogenic differentiation in CD105(-) cells showed superior adhesion efficiency and 2-fold increase of α-actinin expression compared with CD105(+) cells at the maturation stage. Interestingly, levels of activated β1-integrin increased in CD105(-) cells during the process. Additionally, the CD105(-) subpopulation showed 3-fold increase of phosphorylated FAK(Y397) compared to CD105(+) cells. Results also indicate that ERK1/2 was activated during CD105(-) bone differentiation and participation of mitogen-activated protein kinase (MAPK)-p38 in CD105(+) differentiation through a focal adhesion kinase (FAK)-independent pathway. In vivo trial demonstrated that grafts containing CD105(-) showed osteocytes embedded in a mineralized matrix, promoted adequate graft integration, increased host vascular infiltration, and efficient intramembranous repairing. In contrast, grafts containing CD105(+) showed deficient endochondral ossification and fibrocartilaginous tissue. Based on the expression of α-actinin, FAKy,(397) and ERK1/2 activation, we define maturation stage as critical for bone graft assembling. By in vitro assays, CD105(-) subpopulation showed superior adhesion efficiency compared to CD105(+) cells. Considering in vitro and in vivo assays, this study suggests that integration of a scaffold with CD105(-) subpopulation at the maturation stage represents an attractive strategy for clinical use in orthopedic bioengineering.

Confidentiality and data sharing: vulnerabilities of the Mexican Genomics Sovereignty Act

A law known as "Genomic Sovereignty Act", instituted in 2011, regulates research on the human genome in Mexico. This law establishes Government regulations for the exportation of DNA samples from Mexican nationals for population genetics studies. The Genomic Sovereignty Act protects fundamental human values, as confidentiality and non-discrimination based on personal genetic information. It also supports the development of the genome-based medical biotechnology and the bio-economy. Current laws for the protection of the genomic confidentiality, however, are inexplicit and insufficient, and the legal and technological instruments are primitive and insufficient to safeguard this bioethical principle. In addition, this law may undermine efforts of the national and international scientific communities to cooperate with big-data analysis for the development of the genome-based biomedical sciences. The argument of this article is that deficiencies in the protection of the confidentiality of genomic information and limitations in data sharing severely weaken the objectives and scope of the Genomic Sovereignty Act. In addition, the Act may compromise the national biomedical development and the international cooperation for research and development in the field of human genomics.

Enhancement of Ad-CRT/E7-mediated antitumor effect by preimmunization with L. lactis expressing HPV-16 E7

Although current polyvalent vaccines can prevent development of cervical cancer, they cannot be used to treat patients who already have the disease. Adenovirus expressing calreticulin-E7 (Ad-CRT-E7) has shown promising results in the cervical cancer murine model. We also demonstrated that immunization with Lactococcus lactis encoding HPV-16 E7 (Ll-E7) anchored to its surface induces significant HPV-16 E7-specific immune response. Here, we assessed the combination of both approaches in the treatment of a cervical cancer animal model. Intranasal preimmunization of Ll-E7, followed by a single Ad-CRT/E7 application, induced ∼80% of tumor suppression in comparison with controls. Mice treated with a combination of Ll-E7 and Ad-CRT/E7 resulted in a 70% survival rate 300 days post-treatment, whereas 100% of the mice in the control groups died by 50 days. Significant CD8+ cytotoxic T-lymphocytes infiltration was detected in the tumors of mice treated with Ll-E7+Ad-CRT/E7. Tumors with regression showed a greater number of positive cells for in situ TUNEL staining than controls. Our results suggest that preimmunization with Ll-E7 enhances the Ad-CRT/E7-mediated antitumor effect. This treatment provides an enormous advantage over repeated applications of Ad-CRT/E7 by maintaining the effectiveness of the three-dose application of Ad-CRT/E7, but avoiding the high systemic toxicities associated with such repeat treatments.

[Pharmacogenomics of the first-line treatment for gastric cancer: advances in the identification of genomic biomarkers for clinical response to chemotherapy]

Gastric cancer (GC) is often diagnosed at later stages due to the lack of specificity of symptoms associated with the neoplasm, causing high mortality rates worldwide. The first line of adjuvant and neoadjuvant treatment includes cytotoxic fluoropyrimidines and platin-containing compounds which cause the formation of DNA adducts. The clinical outcome with these antineoplastic agents depends mainly on tumor sensitivity, which is conditioned by the expression level of the drug targets and the DNA-repair system enzymes. In addition, some germ line polymorphisms, in genes linked to drug metabolism and response to chemotherapy, have been associated with poor responses and the development of adverse effects, even with fatal outcomes in GC patients. The identification of genomic biomarkers, such as individual gene polymorphisms or differential expression patterns of specific genes, in a patient-by-patient context with potential clinical application is the main focus of current pharmacogenomic research, which aims at developing a rational and personalized therapy (i.e., a therapy that ensures maximum efficacy with no predictable side effects). However, because of the future application of genomic technologies in the clinical setting, it is necessary to establish the prognostic value of these genomic biomarkers with genotype-phenotype association studies and to evaluate their prevalence in the population under treatment. These issues are important for their cost-effectiveness evaluation, which determines the feasibility of using these medical genomic research products for GC treatment in the clinical setting.

RELAGH - The challenge of having a scientific network in Latin America: An account from the presidents

Latin America and the Caribbean region make up one of the largest areas of the world, and this region is characterized by a complex mixture of ethnic groups sharing Iberian languages. The area is comprised of nations and regions with different levels of social development. This region has experienced historical advances in the last decades to increase the minimal standards of quality of life; however, several factors, such as concentrated populations in large urban centers and isolated and poor communities, still have an important impact on medical services, particularly genetics services. Latin American researchers have greatly contributed to the development of human genetics and historic inter-ethnic diversity, and the multiplicity of geographic areas are unique for the study of gene-environment interactions. As a result of regional developments in the fields of human and medical genetics, the Latin American Network of Human Genetics (Red Latinoamericana de Genética Humana - RELAGH) was created in 2001 to foster the networking of national associations and societies dedicated to these scientific disciplines. RELAGH has developed important educational activities, such as the Latin American School of Human and Medical Genetics (ELAG), and has held three biannual meetings to encourage international research cooperation among the member countries and international organizations. Since its foundation, RELAGH has been admitted as a full regional member to the International Federation of Human Genetics Societies. This article describes the historical aspects, activities, developments, and challenges that are still faced by the Network.

Low-income status is an important risk factor in North East Mexican patients with cystic fibrosis

BACKGROUND. Factors such as environment, income status, as well as access to proper healthcare influence the survival and quality of life of people affected by chronic diseases including cystic fibrosis (CF). Survival factors in Mexican patients with CF have not been reported before, even when it has been estimated that this disease could not be negligible in the Mexican population. OBJECTIVE. To compare the influence of the mutant allele ΔF508 and environmental factors on the survival of Mexican CF patients. MATERIAL AND METHODS. We collected epidemiological data of 40 patients molecularly tested between 1987 and 2008 in the Clínica de Fibrosis Quística from the Hospital Universitario of the Universidad Autónoma de Nuevo León in Northeastern México. Kaplan-Meier plots and survival statistics were estimated and compared. RESULTS. Survival analysis revealed statistical significance for low-income status (p = 3.13 x 10-6), cor pulmonale (p = 0.00169), severe pulmonary disease (p = 0.00136), and BMI ≤15 kg/m2 (p = 0.00678). Statistical significance was not observed for the predominant allele ΔF508 considering two (p = 0.992), one (p = 0.503) or no (p = 0.403) mutant allele. CONCLUSIONS. Low income status was the most detrimental factor; followed by cor pulmonale, severe pulmonary disease and BMI ≤ 15 kg/m2 for the survival in North East Mexican patients with CF. Carrying the ΔF508 allele did not influence survival.

Delineation of a de novo 7q21.3q31.1 Deletion by CGH-SNP Arrays in a Girl with Multiple Congenital Anomalies Including Severe Glaucoma

In this study, we present a female patient with a constitutional de novo deletion in 7q21.3q31.1 as determined by G-banding and CGH-SNP arrays. She exhibited, among other features, psychomotor retardation, congenital severe bilateral glaucoma, a cleft palate, and heart defect. Microarray assay disclosed a deleted 12.5-Mb region roughly 88 kb downstream the ectrodactyly critical region; thus, the patient's final karyotype was 46,XX.arr 7q21.3q31.1(96,742,140-109,246,085)×1 dn. This girl represents the fourth patient described so far with congenital glaucoma and a deletion encompassing or overlapping the 7q21.3q31.1 region, and confirms the presence of a locus or loci related to such a clinical feature. According to our results, the proneness to ocular defects secondary to 7q intermediate deletions could be caused by co-deletion of TAC1, HBP1, and a small cluster of cytochrome P450 genes (subfamily 3A). This conclusion is supported by their functional roles and expression locations as well as because TAC1 is related to the functional pathway of the MYOC gene whose mutations are linked to glaucoma. Moreover, given that this girl is clinically reminiscent of several phenotypes related to diverse deletions within 7q21q32, our results and observations offer a general overview of the gene content of deletions/phenotypes overlapping 7q21.3q31.1 and confirm that loci distal to DLX genes including the CUX1 gene and potential regulatory elements downstream from DLX5 are unrelated to ectrodactyly.

De novo MECP2 disomy in a Mexican male carrying a supernumerary marker chromosome and no typical Lubs syndrome features

Xq28 duplication, including the MECP2 gene, is among the most frequently identified Xq subtelomeric rearrangements. The resulting clinical phenotype is named Lubs syndrome and mainly consists of intellectual disability, congenital hypotonia, absent speech, recurrent infections, and seizures. Here we report a Mexican male patient carrying a supernumerary marker chromosome with de novo Xq28 gain. By MLPA, duplication of MECP2, GDI1, and SLC6A8 was found and a subsequent a-CGH analysis demonstrated that the gain spanned ~2.1Mb. Despite gain of the MECP2 gene, the features of this patient do not evoke Lubs syndrome. Probably the mosaicism of the supernumerary marker chromosome is modifying the phenotype in this patient.

[Determination of molecular genetic markers in acute coronary syndromes and their relationship to cardiovascular adverse events]

INTRODUCTION

The genes coding for proteins due to their activity in several metabolic pathways could be related with the onset of acute coronary syndromes.

OBJECTIVE

Relationship among polymorphisms and adverse events in.

METHODS

Prospective. In--hospital, one--year follow-up. Inclusion Acute coronary syndromes with ST elevation or depression secondary to atherothrombosis, clinical stability. In all, polymerase chain reaction and length polymorphism of restriction fragments. By standardizing chain reactions and genotyping,a preliminary analysis of distribution of genotypes was performed for each polymorphism and no deviations were observed in the law of Hardy-Weinberg equilibrium (P>.05).

RESULTS

From 2003 to 2005, 150 subjects were enrolled. We analyzed 14 polymorphisms in 9 genes (fibrinogen, factor v, vii, ii, xiii, plasminogen activator and inhibitor-1, C-reactive protein). In acute coronary syndromes, fibrinogen>450 mg/dL and white blood count 8500 cells/mm(3) were markers of poor prognosis to one year. Regression analysis identified the -148 CT/TT and fibrinogen -717 AG/GG of C-reactive protein as a marker of recurrent ischemia and reinfarction 1691GA + AA.

CONCLUSION

We are showing a relationship among polymorphisms involved in inflammation and hemostasis with adverse events in the acute phase and follow-up in acute coronary syndromes patients that could be considered as markers of ischemic heart disease. Larger sample is needed to confirm these results.

A de novo sSMC(22) Characterized by High-Resolution Arrays in a Girl with Cat-Eye Syndrome without Coloboma

Cat-eye syndrome (CES) results from trisomy or tetrasomy of proximal 22q originated by a small supernumerary marker chromosome (sSMC). Two critical regions for the major clinical features of CES (CESCRs) have been suggested; however, CES clinical presentation often does not correlate with the sSMC genetic content. We report here a CES girl without coloboma and carrier of a de novo type I sSMC(22) as determined by G- and C-banding, NOR staining and microarrays. This sSMC included 6 distal genes outside the original CESCR and led to a tetrasomy for 22q11.1-22q11.21. The patient's final karyotype was 47,XX,+psu dic(22)(q11.21).arr 22q11.1q11.21(15,250,000-17,035,860)×4 dn. The amplified region outside of CESCR included some genes that may be related to neurologic, heart and renal abnormalities. Conversely, even though the amplification included the CECR2 gene, a major candidate for eye features, there was no coloboma in the patient. The genetic delineation of the present sSMC further strengthens that the CES clinical presentation does not fit completely with the duplicated genetic content and that CES is actually a genomic disorder. Furthermore, since we observed no mosaicism, we believe that other mechanisms might be behind the variability of CES phenotypes as well, mainly those related with functional interactions among amplified genes.

Evaluating SKI as a candidate gene for non-syndromic cleft lip with or without cleft palate

Non-syndromic cleft lip with or without cleft palate (NSCL/P) is one of the most common of all congenital malformations and has a multifactorial etiology. Findings in mice suggest that the v-ski sarcoma viral oncogene homolog (SKI) gene is a candidate gene for orofacial clefting. In humans, a significant association between rs2843159 within SKI and NSCL/P has been reported in patients from the Philippines and South America. In the South American patients, the association was driven by the subgroup of patients with non-syndromic cleft lip only (NSCLO). Here we investigated the association with rs2843159 in a Mayan Mesoamerican population (172 NSCL/P patients and 366 controls). In addition, we analyzed the phenotypic subgroups NSCLO and non-syndromic cleft of lip and palate (NSCLP). A trend towards association between rs2843159 and NSCL/P was observed in the Mayan cohort (P = 0.097), and we found a stronger association in the NSCLP subgroup (P = 0.072) despite a limited sample size. To investigate whether other common variants within the SKI gene contribute to NSCL/P susceptibility in European and Asian populations, we also analyzed genotypic data from two recent genome-wide association studies using set-based statistical approaches. These analyses detected a trend toward association in the European population. Our data provide limited support for the hypothesis that common SKI variants are susceptibility factors for NSCL/P.

Oncolytic virotherapy

Current oncolytic virotherapy strategies are based in the accumulated understanding of the common molecular mechanisms displayed during cell transformation and viral infection, like cell cycle and apoptosis deregulations. Oncolytic virotherapy aims to achieve a strong cytolytic effect, highly restricted to transformed cells. Here, we describe the oncolytic virotherapy defined as the use of viruses like antitumor agents (wild and gene-modified oncolytic viruses) and the developed strategies to increase antitumor efficacy and safety. In addition, we discuss the advances and challenges concerning the use virotherapy in animal models and clinical trials. Some clinical trials of virotherapy have demonstrated promising results, particularly when combined with standard antineoplastic therapies. These preliminary accomplishments are opening the field for more research in several aspects, like vector modifications, pharmacodynamics, biosafety, new clinical applications, etc.

Preclinical evaluation of the therapeutic effect of adenoviral vectors in human papillomavirus-dependent neoplasias

Gene therapy with adenoviral vectors can eliminate neoplasic cells through selective replication and/or through pro-apoptotic, immunogenic or suicide gene expression. However, an adenoviral vector may provide anti-cancerous effects even in the absence of replication or therapeutic gene expression. The present study evaluates the therapeutic effects caused by the administration of an adenoviral vector, alone, in HPV-dependent neoplasias (HPV-N). In vivo trials were carried out in two HPV-N mouse models. One model was immunocompetent and the other was immunodeficient. In both models, the effect of intratumoral administration of saline solution (PBS) was compared with administration of an adenoviral vector that had no replicative capacity or therapeutic gene (Ad-BGal). In the immunocompetent mice, Ad-BGal adenoviral vector administration significantly reduced tumor growth, compared with PBS. No differences were observed in the immunodeficient mice. In conclusion, the present study lends support to the use of adenoviral vectors in HPV-N treatment since they are capable of generating an antitumoral effect in immunocompetent individuals, even in the absence of a therapeutic gene or viral vector replication.

Frequency of protease and reverse transcriptase drug resistance mutations in naïve HIV-infected patients

BACKGROUND

Infections with drug-resistant HIV viruses in naïve subjects may cause antiretroviral (ARV) treatment failure. The prevalence of ARV resistance mutations in HIV-1 transcripts of infected naïve patients from northeast Mexico was determined in this study.

METHODS

RNA was extracted from plasma samples of 42 naïve individuals who were diagnosed between February 2001 and September 2003 as HIV-1 infected. Both protease (Pr) and reverse transcriptase (RT) were sequenced in 30 patients. In six samples only the RT segment was sequenced and in three samples only the protease segment was analyzed.

RESULTS

One of 36 isolates (2.8%) had the M184V resistance mutation to nucleoside retrotranscriptase inhibitors. In the Pr segment, only minor mutations were detected in 27/33 isolates (81.8%).

CONCLUSIONS

In this first study, prevalence of major mutations associated with ARV resistance in naïve patients in northeast Mexico is low compared to other countries, perhaps due to a low level of exposure of this population to ARV drugs.

A potent replicative delta-24 adenoviral vector driven by the promoter of human papillomavirus 16 that is highly selective for associated neoplasms

BACKGROUND

Several human epithelial neoplasms are associated with high-risk strains of human papillomavirus (HPV) such as cervical, anorectal, and other carcinomas. For some tumor types the current therapeutic tools are only palliative. Conditionally replicative adenoviruses (CRAds) are promising antineoplastic agents, which also can trigger confined antitumor effects.

METHODS

We constructed a series of CRAds driven by the upstream regulatory promoter region (URR) of an Asian-American variant of HPV-16, which contained different mutations at the E1A region (dl1015 and/or Delta24) and wild-type. All vectors were tested in vitro for viral replication and cytotoxicity. Viral DNA replication and E1A expression were also assessed by quantitative PCR. Finally, we confirmed the antitumoral efficacy of this vector in injected and non-injected xenotransplanted cervical tumors in a murine model for tumor regression and survival studies.

RESULTS

A vector denominated Ad-URR/E1ADelta24 displayed a potent cytopathic effect associated with high selectivity for HPV+ cell lines. We found that the oncolytic effect of this CRAd was comparable to Ad-wt or Ad-Delta24, but this efficacy was significantly attenuated in HPV- cell lines, an effect that was contributed by the URR promoter. Ad-URR/E1ADelta24 was very effective to control tumor growth, in both, injected and non-injected tumors generated with two different HPV+ cell lines.

CONCLUSIONS

CRAd Ad-URR/E1ADelta24 is a highly selective vector for HPV+ cell lines and tumors that preserves the oncolytic efficacy of Ad-wt and Ad-Delta24. Our preclinical data suggest that this vector may be useful and safe for the treatment of tumors induced by HPV, like cervical cancers.

[Fibrinogen. Cardiovascular risk factor or marker?]

Endothelial dysfunction and inflammation play a crucial role in all stages of atherosclerosis, from the beginning, during progression, and, finally, in its highest clinical expression: acute coronary syndromes. In this process, fibrinogen, an acute phase reactant with active participation in endothelial function, thrombosis and inflammation has proved to be an independent variable to cardiovascular risk together with its participation in resistance phenomena to different antithrombotic approaches. The reasons by which fibrinogen is elevated in cardiovascular disease and atherosclerosis are, in general, only incompletely understood; but all cells involved in the atherogenetic process are able to produce cytokines, which induce an acute phase reaction that increases fibrinogen levels in plasma. The potential pathophysiological mechanisms by which elevated fibrinogen levels mediate cardiovascular risk are multiple. Fibrinogen forms the substrate for thrombin an represents the final step in the coagulation cascade, it is essential for platelet aggregation, it modulates endothelial function, it promotes smooth muscle cell proliferation and migration, it interacts with the binding of plasmin with its receptor and, finally, it represents a major acute phase protein. Epidemiological studies have established sufficient evidence to consider fibrinogen as a strong, consistent, and independent cardiovascular risk marker or factor. Based on all these implications, the target of this review is an analysis of physiopathogenic and epidemiologic evidence searching for guidelines to establish whether fibrinogen as a risk factor or marker is the lost link between cardiovascular disease and classic risk factors.

CONCLUSION

Analyses of the respective studies suggest that fibrinogen is an important and independent cardiovascular risk factor, clearly associated with conventional risk factors and genetic polymorphisms. Whether or not fibrinogen is causally involved in atherothrombogenesis still remains to be determined and despite of unsolved issues that are waiting conclusive answers, fibrinogen has emerged as an important additional marker of cardiovascular risk.

[The effect of MTHFR polymorphisms, pregnancy and first intercourse on cervical cancer in a population from the Northeastern Mexico]

OBJECTIVE

To investigate the possible association among MTHFR polymorfhisms, environmental factors and cervical cancer (CC) in the Mexican population.

METHODS

Seventy patients with CC and 89 control women were questioned about clinical data and their 677 and 1298 genotypes of MTHFR gene were analized.

RESULTS

Multipregnancies (0-2 vs. > or = 3, OR 2.1), an early age of first intercourse (IVS) (17 < or = vs. > or = 18 years, OR 4.3) or both factors (OR 3.5) were significantly associated with CC. MTHFR 677, 1298 polymorphisms and their combinations were not different between cases and controls. However, a significant association between pregnancies, IVS and MTHFR polymorphisms (presence of 1298C allele or 677TT genotype) was observed. The 1298C allele plus multipregnancies and IVS < or = 17 years, or both factors, increased 4.3, 5.3, and 11.8 times the risk for CC, respectively, while 677TT genotype changed the risk 2.0, 1.9, and 4.2 times, respectively.

CONCLUSION

The 1298C allele increases the risk of CC strongly in women with multipregnancies and early age of IVS, while 677TT genotype has a lower risk without becoming a protection factor.

[Viruses: an important cause of human cancer]

More than 90 years have passed since Peyton Rous reported that a tumor was transmitted between chickens like an infection disease. Currently the viruses are considered the second most important cause of cancer in humans and contribute to 10 to 20% of all cancer cases in the world, some of them being very common, like cervical and hepatocellular carcinomas. Human recognized cancer viruses include HPV, HBV, HCV, EBV, HHV-8 and HTLV-1. The knowledge of how viruses participate in the ethiopathogeny of cancer will allow fighting the disease with similar strategies than those that we use to control those infective agents now days. Great efforts are being initiated to decrease incidence of the neoplasms by preventing the initial infection or by prophylactic vaccination.

[Genetic therapy of cancer]

Gene therapy is a new modality of treatment in which a gene is used to modify or add new biochemical properties to a patient's target cells with therapeutics purposes. Currently, this experimental therapy is under intensive development as an alternative to treat cancer, because it is possible that this therapy may generate a higher antineoplastic activity, more tissue selectivity and less contralateral effects than conventional therapy. After a decade of preclinical and clinical assays, still there are several obstacles that impose limits to the antineoplastic efficacy of this therapy. However, with the advances in molecular biology and related fields, there is a promise to improve, expand and strength the powerful antineoplastic arsenal of gene therapy.

Folate levels and N(5),N(10)-methylenetetrahydrofolate reductase genotype (MTHFR) in mothers of offspring with neural tube defects: a case-control study

BACKGROUND

Neural tube defects (NTDs) have been associated with biochemical factors involved in the conversion of homocysteine to methionine as folate deficiency and the mutation 677T in the N(5),N(10)-methylenetetrahydrofolate reductase gene (MTHFR).

METHODS

A case-control study was performed to detect this mutation in 38 unrelated women with NTD deceased products and 31 mothers without antecedents of NTD offspring. All products were born in Nuevo León (northeastern Mexico) during 1997. Erythrocyte and plasmatic folate levels and the genotype of the 677 polymorphism at the MTHFR locus were analyzed in both groups.

RESULTS

Although no significant differences were found in mean blood folate levels, the percentage of women in the case group with erythrocyte folate levels <160 ng/mL was significantly higher than in the control group (75 vs. 51.2%, p <0.05). The proportion of women with plasma folate levels <3.5 ng/mL was higher in the case group (16.2 vs. 0%, p <0.01). Genotype analysis demonstrated a significantly higher proportion of 677T homozygous mothers with NTD products (39.6 vs. 9.1%, p <0.05). Allele frequencies for the 677T mutation were 0.55 and 0.36 for cases and controls, respectively. The odds ratio (OR) for having a NTD product was 6.1 (95%, CI 1.56-23.6) for homozygous 677T mothers vs. homozygous 677C and heterozygous mothers. Significantly low levels of erythrocyte folate were found in the 677C homozygous case group and in plasma folate in the 677C/677T heterozygous case mothers.

CONCLUSIONS

Our study suggests that folate deficiency and MTHFR unfavorable genotype in mothers are important risk factors for severe NTD phenotype in our population.

[677T mutation of the MTHFR gene in adenomas and colorectal cancer in a population sample from the Northeastern Mexico. Preliminary results]

INTRODUCTION

Adequate intake of folates has been associated to low prevalence of colon cancer. Methylenetetrahydrofolate reductase enzyme (MTHFR) plays an important role in folate metabolism. The role of the 677 mutation at the MTHFR gene in the risk for colorectal cancer remains controversial. A recent report established that this mutation has a high prevalence in the healthy Mexican population.

AIMS

To analyze the prevalence of 677T MTHFR mutation in patients with colorectal cancer and controls without chronic gastrointestinal disorders.

METHODS

Seventy-four colorectal cancer, 32 adenomas and 110 normal samples were analyzed. Patients and controls were matched for sex and age. For each sample, DNA isolation, PCR, and mutation detection by restriction enzyme digestion were performed to determine the allele at the 677 position in the MTHFR gene.

RESULTS

Genotype 677C/677C was found in 18.7, 20.3, and 30.9% in adenomas, cancer lesions and controls, respectively. Frequencies of the 677C/677T genotype were 59.4, 56.7, and 47.3%, in adenomas, cancer lesions, and controls, respectively. Genotype 677T/677T was found in 21.9, 23.0, and 21.8% in adenomas, cancer lesions, and controls, respectively. The odds ratio between genotypes carrying the mutation (T/T and C/T) and normal genotype (CC) was 1.81 (IC 95% 0.97-3.3), chi 2 = 3.5, p = 0.06.

CONCLUSION

Our results showed that persons who carry the 677T mutation at MTHFR locus have a tendency for an increased risk for colorectal cancer. This study supports the basic concept that low levels of folic acid contribute with the colorectal cancer pathogenesis. Our lack of statistic significance may be due to reduced sample size.

[Genetic aspects of asthma]

Asthma is a complex disease associated with bronchial hyperreactivity and atopy, making asthma a disease with a phenotype that has been clinically difficult to define. Despite intense research, prevalence of asthma remain relatively high. The key reason for the high prevalence and morbility is that the fundamental mechanisms predisposing individuals to the development of asthma are not understood. Familial aggregation observed in this pathology has prompted for the search of an involved genetic component. This task is difficult due to the complex nature of asthma. A universally accepted definition for this disease is not available, clinical expression can be modulated by environmental factors, and inheritance does not follow a clear Mendelian pattern. Establishment of more precise clinical and laboratory criteria has improved the design and interpretation of genetic studies. Twin analysis and segregation studies have demonstrated an important genetic component with a probably multifactorial pattern of inheritance. "Sib pair" studies and familial segregation analyses have shown linkage between some chromosomal regions and asthma, including chromosome 5, 6, 7, 11 and 14. The search for major genes in these chromosomal segments has been focused on loci involved in the allergic process. Among these, the loci for IL-9 and IL-13 in chromosome 5 seem to play an important role in the pathogenesis of asthma. Understanding the fundamental gene-environmental interactions in the development of asthma should lead to earlier identification of susceptible individuals and more effective approaches for disease prevention.

CFTR mutations in three Latin American countries

We analyzed 192 cystic fibrosis (CF) alleles in three Latin American countries: Mexico, Colombia, and Venezuela. Mutation screening was performed by polymerase chain reaction (PCR) and a reverse dot blot detection kit that enables determination of 16 of the most common CF mutations worldwide. Mutations were detected in 47.9% of the screened CF alleles. The most prevalent CF allele was DeltaF508 (39. 6%). The remaining 16 non-DeltaF508 detectable mutations represented 8.3% of the CF alleles. Among them, the G542X, N1303K, and 3849+10kb C>T were the most common. Although the frequency of DeltaF508 described here is lower than that reported for Caucasian populations, including in Spain, it is remarkable that mutation prevalences found in this study resemble those observed in Spain. Two of these mutations, G542X and 3849+10kb C>T, that were relevant in this analysis, have a particularly high incidence in Spanish communities. The low frequency of DeltaF508 described here may be explained by the Amerindian, Caucasian, and Black admixture that occurred in Latin America after the discovery of the New World, and also by the probable occurrence of mutations contributed by the original natives, which were undetectable in this analysis.

Reproductive biology and the process of domestication of the columnar cactus Stenocereus Stellatus in Central Mexico

Pollination biology, breeding system, and floral phenology of the columnar cactus Stenocereus stellatus were studied in wild, wild managed in situ and cultivated populations of central Mexico, in order to examine whether these aspects have been modified under domestication and whether they determine reproductive barriers between wild and manipulated individuals. Individuals of both wild and manipulated populations are self-incompatible, indicating that artificial selection has not modified the breeding system. Their pollination biology is also similar. Anthesis is mainly nocturnal, with a peak of nectar production between 0200 and 0400 when the stigma presents maximum turgidity. Nocturnal visitors are the effective pollinators. Nearly 75% of flowers exposed for nocturnal pollination set fruit, while none of the flowers exposed for diurnal pollination produced fruits. The bats Leptonycteris curasoae, L. nivalis, and Choeronycteris mexicana (Glossophaginae) are the most likely pollinators, and their time of foraging is synchronized with the time of nectar production and stigma receptivity in S. stellatus. Bats potentially move pollen over a considerable distance, so there is apparently no spatial isolation to prevent pollen exchange between wild and cultivated populations. Phenological studies showed that there are also no apparent temporal barriers. However, manual cross pollination failed between some domesticated and wild phenotypes, suggesting that gene flow between wild and cultivated populations might be limited by pollen incompatibility.