Objective The global burden of diabetes mellitus will impact strongly American countries in the coming decades. Type 2 diabetes mellitus (T2DM) is a multifactorial disease and the basis for its genetic susceptibility remains not fully understood. Different population studies have demonstrated that variants of the TCF7L2 gene are strongly associated with an increased risk of T2DM. Moreover, institutions or countries with limited budget to conduct genetic research need cost effective methods for detecting DNA variants. Subjects and methods We standardized a rapid and simple allele-specific PCR method for genotyping the rs12255372 single nucleotide polymorphism (SNP) in a pilot study exploring the association of three TCF7L2 polymorphisms (rs7903146, rs12255372 and DG10S478) with T2DM in 70 patients and 73 controls from Venezuela. Results The performance of the designed allele-specific PCR reaction for rs12255372 genotyping was reliable and accurate. Patients carrying the TCF7L2 rs7903146 T allele (CT + TT genotypes) and heterozygous CT genotype had a significantly higher risk for T2DM (OR = 2.9 and 2.3, respectively). Although rs12255372 and DG10S478 risk alleles predominated in T2DM group no statistical significance was found. Conclusions We developed a novel allele-specific PCR method for easier and rapid detection of rs12255372 polymorphism without the use of expensive instrumentation and reagents. Our study in a relatively small sample of the Venezuelan population replicated the association of the rs7903146 SNP with T2DM. Further studies with larger sample size and more biochemical data should be conducted to explore the genetic basis of T2DM susceptibility in Venezuela.

Helicobacter pylori es una bacteria que coloniza la mucosa del estómago produciendo enfermedades gástricas crónicas. Las cepas que expresan el factor de virulencia CagA se unen al epitelio gástrico e inyectan en él esta proteína, la cual es activada por fosforilación en residuos de tirosina ubicados en el motivo EPIYA. Dependiendo del número y tipo de motivo EPIYA (EPIYA-A, B, C y D), se inducen transformaciones celulares que juegan un papel importante en el desarrollo de enfermedades gastroduodenales asociadas con H. pylori. El objetivo de este trabajo fue determinar la frecuencia de las variantes de EPIYA en cepas de H. pylori cagA positivas de la región centroccidental de Venezuela. Se estudiaron 81 muestras de ADN extraídas de biopsias gástricas tomadas de individuos con gastritis crónica. El tipo de motivo EPIYA fue determinado por PCR y secuenciación. Solamente se detectaron variantes de EPIYA descritas para países occidentales: ABC (58,0%), ABCC (38,3%) y ABCCC (3,7%). La baja prevalencia detectada de cepas de H. pylori con tres repeticiones de EPIYA-C, las cuales se conocen por generar un mayor riesgo a cáncer gástrico, puede encontrase entre las razones que expliquen la escasa incidencia de cambios histológicos severos en las muestras de gastritis crónica analizadas.

Abstract: Helicobacter pylori is a bacterium that colonizes stomach mucous tissue producing chronic gastric disease. The strains that express the CagA virulence factor adhere to the gastric epithelium and inject this protein, which is activated by phosphorilation at tyrosine residues located in the EPIYA motif. Depending on the number and type of EPIYA motif (EPIYA-A, B, C, and D), cellular transformations are induced which play an important role in the development of H. pylori associated gastro duodenal diseases. The objective of this work was to determine the frequency of the EPIYA variants in cagA positive H. pylori strains from the center-occidental region of Venezuela. The study included 81 DNA samples extracted from gastric biopsies taken from individuals with chronic gastritis. The type of EPIYA motif was determined by PCR and sequencing. Only EPIYA variants described for occidental countries were detected: ABC (58.0%), ABCC (38.3%) and ABCCC (3.7%). The low prevalence of H. pylori strains with three EPIYA-C repetitions detected, which are known to generate a higher gastric cancer risk, could be one of the reasons that explain the low incidence of severe histological changes in the chronic gastric samples analyzed.

Las citoquinas pertenecientes a familia de la interleuquina-1 (IL-1) están codificadas por tres genes diferentes: IL-1A, IL-1B, e IL-1RN, los cuales codifican para IL-1 α, IL-1β, y el antagonista endógeno del receptor de IL-1 (IL-1ra), respectivamente. Las IL-1α e IL-1β actúan como citoquinas pro-inflamatorias, mientras que la IL-1ra se comporta como anti-inflamatoria. Han sido reportados varios polimorfismos bialélicos en los genes de IL-1B, incluyendo IL-1B-511(C/T) e IL-1B+3954(C/T), mientras que IL-1RN presenta en el intrón 2 un polimorfismo VNTR penta-alélico. Los polimorfismos funcionalmente relevantes de estos genes han sido correlacionados con un amplio conjunto de condiciones autoinmunes e inflamatorias crónicas, así como con cáncer. Con el fin de determinar la distribución de estos polimorfismos en la región centroccidental de Venezuela, se estudiaron 100 individuos no relacionados aparentemente sanos. Se extrajo ADN genómico a partir de sangre periférica, y se procedió a la tipificación de los polimorfismos IL-1B-511 e IL-1B+3954 por PCR-RFLP y VNTR de IL-1RN por PCR. Se determinaron las frecuencias alélicas y genotípicas con el programa Arlequín ver. 2.000. Se observó un predominio del alelo T (52%) y del alelo C (82%) en IL-1B-511 y IL-1B+3954, respectivamente. Mientras que para IL-1RN los genotipos más frecuente fueron el 1/1 (47%) y 1/2 (41%). Se compararon los resultados con las frecuencias poblacionales encontradas en otros países, destacándose diferencias significativas con poblaciones de diferente origen étnico. Los resultados podrían proporcionar una referencia valiosa para estudios futuros de asociación con cáncer y enfermedades inflamatorias en Venezuela.

The cytokines belonging to the family of interleukin-1 (IL-1) are encoded by three different genes: IL-1A, IL-1B, and IL-1RN, which encode for IL-1α, IL-1β and the endogenous receptor antagonist for IL-1 (IL-1Ra), respectively. IL-1α and IL-1β operate as pro-inflammatory cytokines, while the IL-1Ra as anti-inflammatory. It has been reported several biallelic polymorphisms in the genes of IL-1B, including IL-1B-511(C/T) and IL-1B+3954(C/T), while IL-1RN presents in intron 2 a penta-allelic VNTR polymorphism. The functionally relevant polymorphisms of these genes have been correlated with a wide range of chronic inflammatory and autoimmune conditions, as well as cancer. In order to determine the distribution of these polymorphisms in the Central-Western region of Venezuela, 100 unrelated apparently healthy individuals were studied. DNA was extracted from peripheral blood, and proceded to the characterization of polymorphisms IL-1B-511 and IL-1B +3954 by PCR-RFLP and VNTR IL-1RN by PCR. Allelic and genotypic frequencies were determined awith the program Arlequin v. 2.0. There was a predominance of T allele (52%) and the C allele (82%) for IL-1B-511 and IL-1B +3954, respectively. While for IL-1RN the more frequent genotypes were 1/1 (47%) and 1/2 (41%). We compare the results with the population frequencies found in other countries, highlighting differences with significant populations of different ethnic origin. These results could provide a valuable reference for future studies of association with cancer and inflammatory diseases in Venezuela.