[Study of the association between the polymorphism of the TNF-α gene and prostate cáncer]. / Estudio de la asociación entre el polimorfismo del gen TNFα y el cáncer de próstata.

BACKGROUND: Prostate cancer is the third cause of cancer death in men in the Western hemisphere and the second cause of cancer death in Zulian men from Venezuela. OBJECTIVE: To determine whether polymorphisms 308 and 238 of the tumor necrosis factor alpha (TNF-α) gene are associated with prostate cancer. METHODS: The DNA that was extracted from the peripheral blood of 40 patients with prostatic specific antigen and 40 controls was amplified by PCR plus digestion with enzymes NcoI and MspI. RESULTS: In the patients, genotypes of the TNF-α-238 polymorphism were observed in 90% GG and 10% GA; in controls, in 97.5% GG and 2.5% GA, odds ratio (OR) = 4,000 for GA. In the patients, genotypes of TNF-α-308 polymorphism were identified in 85% GG and 15% GA, and in controls in 72.5% GG and 27.5% GA, OR = 0.545 for GA and 1.172 for GG. The allelic frequencies for TNF-α-238 in patients were 95% for G and 5% for A; in controls, 98.75% for G and 1.25% for A, with OR = 4,000 for A. The allelic frequencies for TNF-α-308 in the patients were 92.5% for G and 7.5% for A. CONCLUSIONS: There weren't any statistically significant associations. The allele A of the TNF-α-238 polymorphism resulted in a considerable risk factor for prostate cancer.

Antecedentes: El cáncer de próstata es la tercera causa de muerte por cáncer en hombres del hemisferio occidental y la segunda en zulianos de Venezuela. Objetivo: Determinar si los polimorfismos 308 y 238 del gen TNFα están asociados con cáncer de próstata. Métodos: El ADN extraído de sangre periférica de 40 pacientes con antígeno prostático específico y 40 controles fue amplificado por reacción en cadena de la polimerasa más digestión con enzimas NcoI y MspI. Resultados: Respecto al polimorfismo 238 del gen TNFα, en los pacientes se observó 90 % de genotipo GG y 10 % de GA; en los controles, 97.5 % de GG y 2.5 % de GA, razón de momios (RM) = 4.000 para GA. En cuanto al polimorfismo 308, en los pacientes se identificó 85 % de genotipo GG y 15 % de GA; y en los controles, 72.5 % de GG y 27.5 % de GA, RM = 0.545 para GA y 1.172 para GG. Las frecuencias alélicas de TNFα-238 en los pacientes fue de 95 % de G y 5 % de A; en los controles, 98.75 % de G y 1.25 % de A, con RM = 4.000 para A. Las frecuencias alélicas para TNFα-308 en los pacientes fueron 92.5 % de G y 7.5 % de A. Conclusiones: No existieron asociaciones estadísticamente significativas. El alelo A del polimorfismo 238 del gen TNF-α resultó de riesgo para cáncer de próstata.

Identificación de la mutación ΔF508 en afectados con íleo meconial

Objetivo: Identificar la mutación ΔF508 en pacientes con íleo meconial. Ambiente: En el Instituto de Investigaciones Genéticas de la Facultad de Medicina de la Universidad del Zulia. Maracaibo. Métodos: Se estudiaron diez pacientes con ileo meconial. La detección de la mutación ΔF508 se realizó a partir de amplificación por reacción en cadena de la polimerasa de un segmento del gen de fibrosis quística de 98 pares de bases que contiene el codón que codifica a la fenilalanina en la posición 508 y el cual está ausente en los que tienen la mutación. Resultados: Se detectó la mutación ΔF508 en ambos alelos del gen de la fibrosis quística en tres pacientes, en un solo alelo en cinco y en dos no se identificó el alelo ΔF508 en su patrón molecular. Conclusión: El íleo meconial fue el marcador que sugirió el diagnóstico de fibrosis quística y permitió el asesoramiento genético de las familias al confirmar la presencia de la mutación ΔF508.

Objective: To perform ΔF508 mutation in patients with meconium ileus. Setting: In the Genetic Research Institute of the Faculty of Medicine. University of Zulia. Maracaibo. Methods: We studied 10 patients with meconium ileus. Detection of the mutation was performed from the amplification of a 98 pair of bases cystic fibrosis gene segment which contains the codon that encodes fenilalanine in the 508 position by polymerase chain reaction. This amplified product is absent in those who have the mutation. Results: The ΔF508 mutation was detected in both alleles of the cystic fibrosis gene in 3 patients, 5 were heterozygous for this mutation and in two patients were undetectable. Conclusion: Meconium ileus was the marker that suggested the diagnosis of cystic fibrosis and allowed the genetic counseling in this family to confirm the presence of the ΔF508 mutation.

[C677T polymorphism of the methylentetrahydrofolate reductase gene in mothers of children affected with neural tube defects]. / Polimorfismo C677T del gen de la metilentetrahidrofolato reductasa en madres de ninos afectados con defectos del tubo neural.

Neural tube defects (NTD) are the most common congenital anomalies of the central nervous system, with a multifactorial pattern of inheritance, presumably involving the interaction of several genetic and environmental factors. The methylenetetrahydrofolate reductase (MTHFR) gene 677C>T polymorphism has been implicated as a risk factor for NTD. The main objective of this research was to investigate the association of the 677C>T polymorphism of the MTHFR gene as a genetic risk factor for NTD. Molecular analysis was performed in DNA samples from 52 mothers with antecedent of NTD offspring and from 119 healthy control mothers. Using the Polymerase Chain Reaction, a 198 bases pairs fragment was digested with the restriction enzyme Hinfi. 677T MTHFR allele frequencies for the problem and the control groups were 51.92% and 34.45%, respectively, and 677C MTHFR allele frequencies were 48.08% and 65.55%, respectively. There were significant differences in allele (p: 0.002) and genotype (p: 0.007) frequencies between these two groups. The odds ratio (OR) to the TT genotype vs. the CC genotype was estimated as OR: 4.9 [95% CI: 1,347-6.416] p: 0.002; CT+TT vs. CC: OR: 2.9 [95% CI: 1.347-6.416] p: 0.005; TT vs. CT+CC: OR: 2.675 [95% CI: 1,111-6.441] p: 0.024. The data presented in this study support the relationship between MTHFR 677C>T polymorphism and risk in mothers with antecedent of NTD offspring.

Distribution of GSTM1, GSTT1, GSTP1 and TP53 disease-associated gene variants in native and urban Venezuelan populations.

The contemporary Venezuelan population is the product of major admixture process across various historical events, which has provided it a particular genetic background. The aim of this study concerns the analysis of glutathione S-transferase (GST) GSTM1, GSTP1 and GSTT1 genetic variants and five polymorphisms at the TP53 gene, which are related to cancer susceptibility, in an urban/admixed population and five Amerindian tribes (Bari, Panare, Pemon, Warao and Wayuu) from Venezuela. Genotyping was carried out in 120 individuals from an urban sample and 188 Amerindians. The analysis performed on TP53 haplotype and GST allele distribution showed a close correlation for Pemon and Warao populations, while Bari group appears isolated from the other populations. GSTT1 null variant frequency in our admixed (11%) and native samples (0.0-11.4%) was lower when compared with Caucasians, Africans and Asians. Frequency of the GSTP1*Val cancer-associated allele found in Bari (88.6%) and Panare (63.0%) is of the highest so far reported. Fourteen TP53 haplotypes were observed in the admixed populations, whereas only 3 to 5 in Amerindians. To our knowledge this is the first report of GST polymorphisms and TP53 haplotype distribution in Venezuelans. The distribution of most of analyzed polymorphisms in the urban sample is consistent with the admixed origin of the present-day population of Venezuela. While, the inter-ethnic variations in genetic polymorphisms found in Native American tribes seem to be the result of the influence of demographic factors. These results provide additional data for undertaking ethnographic and disease association studies in Venezuela.

Effect of the parental origin of the X-chromosome on the clinical features, associated complications, the two-year-response to growth hormone (rhGH) and the biochemical profile in patients with turner syndrome.

BACKGROUND: It is possible that genes on the X chromosome are expressed differently depending of its parental origin. The objective of this study was to determine the influence of the parental origin of the X-chromosome on phenotypic variability, response to rhGH and on the biochemical profile of TS patients. METHODS: This was a cross-sectional multicenter correlational study carried out over three years in six Latin-American university hospitals. Unrelated 45,X TS patients (n = 93; 18.3 ± 8.5 years )) were evaluated. A subgroup (n = 34) of the patients were prospectively treated with rhGH over two years. DNA profiles of patients and their mothers were compared to determine the parental origin of the retained X-chromosome through 10 polymorphic X-chromosome-STRs. The association with clinical features, biochemical profiles and anthropometric data at the beginning and after two years of rhGH treatment was determined. RESULTS: Seventy two percent of patients retained the maternal X chromosome (Xm). A trend towards significance between maternal height and patients final height (p ≤ 0.07) in 45,Xm subjects was observed. There was no correlation between paternal height and patient height. No differences were detected between both groups in regard to dysmorphic features, classical malformations or increase in the height-SDS after rhGH. There were higher levels of triglycerides, total and LDL cholesterol in patients >20 years who retained the Xm. CONCLUSIONS: The parental origin of the retained X chromosome may influence lipid metabolism in TS patients, but its effect on growth seems to be minimal. No parental-origin-effect on the phenotypic features, associated anomalies and on the growth response to rhGH was found in 45,X TS individuals.

Defecto del tubo neural, prolapso genital neonatal y polimorfismo de la metiltetrahidrofolato reductasa: presentación de un caso / NTD, neonatal genital prolapse and methylenetetrahydrofolate reductase polymorphism: case report

Se reporta el caso de una recién nacida femenina de 26 días de edad, con mielomeningocele toracolumbar, hidrocefalia y prolapso genital. En el Instituto de Investigaciones Genéticas de la Facultad de Medicina de la Universidad del Zulia, Maracaibo, se analizaron 6 muestras de ácido desoxirribonucleico, correspondientes a afectada, madre, padre y 3 controles. En esta familia se interrelacionan la anomalía congénita y los factores de riesgo genético y ambiental, lo que permitió adecuado asesoramiento genético.

We report the case of a female newborn 26 days old with thoracolumbar myelomeningocele, hydrocephalus and genital prolapse. In Genetic Research Institute of the Faculty of Medicine, University of Zulia, Maracaibo, 6 samples of oxyribonucleic acid corresponding to affected mother, father and 3 controls were analyzed. In this family are interrelated congenital anomaly and genetic risk factors and environmental, allowing appropriate genetic counseling.

Continent-wide decoupling of Y-chromosomal genetic variation from language and geography in native South Americans.

Numerous studies of human populations in Europe and Asia have revealed a concordance between their extant genetic structure and the prevailing regional pattern of geography and language. For native South Americans, however, such evidence has been lacking so far. Therefore, we examined the relationship between Y-chromosomal genotype on the one hand, and male geographic origin and linguistic affiliation on the other, in the largest study of South American natives to date in terms of sampled individuals and populations. A total of 1,011 individuals, representing 50 tribal populations from 81 settlements, were genotyped for up to 17 short tandem repeat (STR) markers and 16 single nucleotide polymorphisms (Y-SNPs), the latter resolving phylogenetic lineages Q and C. Virtually no structure became apparent for the extant Y-chromosomal genetic variation of South American males that could sensibly be related to their inter-tribal geographic and linguistic relationships. This continent-wide decoupling is consistent with a rapid peopling of the continent followed by long periods of isolation in small groups. Furthermore, for the first time, we identified a distinct geographical cluster of Y-SNP lineages C-M217 (C3*) in South America. Such haplotypes are virtually absent from North and Central America, but occur at high frequency in Asia. Together with the locally confined Y-STR autocorrelation observed in our study as a whole, the available data therefore suggest a late introduction of C3* into South America no more than 6,000 years ago, perhaps via coastal or trans-Pacific routes. Extensive simulations revealed that the observed lack of haplogroup C3* among extant North and Central American natives is only compatible with low levels of migration between the ancestor populations of C3* carriers and non-carriers. In summary, our data highlight the fact that a pronounced correlation between genetic and geographic/cultural structure can only be expected under very specific conditions, most of which are likely not to have been met by the ancestors of native South Americans.

Development of a panel of genome-wide ancestry informative markers to study admixture throughout the Americas.

Most individuals throughout the Americas are admixed descendants of Native American, European, and African ancestors. Complex historical factors have resulted in varying proportions of ancestral contributions between individuals within and among ethnic groups. We developed a panel of 446 ancestry informative markers (AIMs) optimized to estimate ancestral proportions in individuals and populations throughout Latin America. We used genome-wide data from 953 individuals from diverse African, European, and Native American populations to select AIMs optimized for each of the three main continental populations that form the basis of modern Latin American populations. We selected markers on the basis of locus-specific branch length to be informative, well distributed throughout the genome, capable of being genotyped on widely available commercial platforms, and applicable throughout the Americas by minimizing within-continent heterogeneity. We then validated the panel in samples from four admixed populations by comparing ancestry estimates based on the AIMs panel to estimates based on genome-wide association study (GWAS) data. The panel provided balanced discriminatory power among the three ancestral populations and accurate estimates of individual ancestry proportions (R² > 0.9 for ancestral components with significant between-subject variance). Finally, we genotyped samples from 18 populations from Latin America using the AIMs panel and estimated variability in ancestry within and between these populations. This panel and its reference genotype information will be useful resources to explore population history of admixture in Latin America and to correct for the potential effects of population stratification in admixed samples in the region.

CYP2D6 gene variants in urban/admixed and Amerindian populations of Venezuela: pharmacogenetics and anthropological implications.

BACKGROUND: Differences in genes encoding enzymes involved in the biotransformation of a large number of compounds, such as CYP2D6, are related to inter-individual and inter-ethnic variability in the metabolism of many drugs, which have also been linked to susceptibility to cancer and other health outcomes. Therefore, populations are likely to benefit from inclusion in pharmacogenetic research studies. AIM: To determine the frequency of functionally important allele variants of CYP2D6 gene in a sample of an Urban/admixed and five Amerindian Venezuelan populations. SUBJECTS AND METHODS: DNA of 328 unrelated volunteers was analysed for the presence of CYP2D6 *2, *3, *4, *5, *6 and *10 variants. RESULTS: The frequency in the Urban/admixed population for *2, *3, *4, *5, *6 and *10 alleles was 37.9%, 0%, 13.4%, 2.0%, 1.2% and 4.0%, respectively. In the Bari population, the prevalence of *4 allele associated with decreased enzyme activity was observed in 42.5%, whereas the poor metabolizer genotype *4/*4 was found in 25%. In the Panare, Pemon, Warao and Wayuu populations the *4 allele was found in 5.4%, 2.5%, 1.7% and 4.2%, respectively. The *10 allele frequency found in Amerindians (0.0-6.3%) was lower than reported for Asians. CONCLUSION: The results are consistent with the known genetic admixture origin of most Venezuela populations. Nevertheless, the observed significant differences among Amerindians highlight the need for pharmacogenetic studies taking into account biogeographical and anthropological considerations.

Polimorfismos intragénicos de los genes de los factores VIII y IX y su utilidad en el diagnóstico indirecto de portadoras de hemofilias A y B / Intragenic polymorphisms of factor VIII and IX genes and their utility in the indirect diagnosis of carriers of haemophilias A and B

Las Hemofilias A y B se consideran enfermedades hereditarias ligadas al sexo debidas a mutaciones en los genes que codifican para los factores VIII y IX respectivamente, ocasionando deficiencia en los niveles de la concentración plasmática de estas proteínas y cuyos roles son los de participar activamente en el mecanismo de la coagulación sanguínea. Se han reportado diversas mutaciones responsables de la alteración de estos genes; razón por la cual resulta poco práctico la aplicación de un método de diagnóstico molecular directo para la identificación de mujeres portadoras, por ello, una estrategia diagnóstica apropiada es el análisis indirecto de polimorfismos ligados al gen. El objetivo de este trabajo fue identificar mujeres portadoras en diversas familias con antecedentes de HA y HB residentes del estado Zulia, en Venezuela, caracterizando polimorfismos intragénicos de los genes del factor VIII y factor IX, los cuales permitieron asignar haplotipos y diagnosticar o descartar el estado portador al 95 por ciento de las mujeres que requerían el estudio para HA y al 100 por ciento para HB.

Haemophilia A and B are considered sex-linked inherited diseases caused by mutations in genes that encode factors VIII and IX, respectively. This results in the deficiency of these proteins plasma levels which are actively involved in the mechanism of blood coagulation. It has been reported that several mutations are responsible for the alteration of these genes, which is why the application of a molecular diagnostic method for the direct identification of female carriers is impractical. An appropriate diagnostic strategy is the indirect analysis of polymorphisms linked to the gene. The aim of this study was to identify female carriers in different families with history of HA and HB that live in Zulia State, Venezuela, characterizing intragenic gene polymorphisms of the clotting factors VIII and IX, which helped to identify and assign haplotypes, to diagnose or to exclude the carrying condition, to 95 percent of women who were needing the study for HA and to 100 percent for HB.

[Intragenic polymorphisms of factor VIII and IX genes and their utility in the indirect diagnosis of carriers of Haemophilias A and B]. / Polimorfismos intragénicos de los genes de los factores VIII y IX y su utilidad en el diagnóstico indirecto de portadoras de Hemofilias A y B.

Haemophilia A and B are considered sex-linked inherited diseases caused by mutations in genes that encode factors VIII and IX, respectively. This results in the deficiency of these proteins plasma levels which are actively involved in the mechanism of blood coagulation. It has been reported that several mutations are responsible for the alteration of these genes, which is why the application of a molecular diagnostic method for the direct identification of female carriers is impractical. An appropriate diagnostic strategy is the indirect analysis of polymorphisms linked to the gene. The aim of this study was to identify female carriers in different families with history of HA and HB that live in Zulia State, Venezuela, characterizing intragenic gene polymorphisms of the clotting factors VIII and IX, which helped to identify and assign haplotypes, to diagnose or to exclude the carrying condition, to 95% of women who were needing the study for HA and to 100% for HB.

Novel mutations identification in exon 4 of LDLR gene in patients with moderate hypercholesterolemia in a Venezuelan population.

Familial hypercholesterolemia (FH) is an autosomal dominant disease characterized by increase in low-density lipoprotein (LDL) cholesterol levels and premature coronary artery disease. In Venezuela, the molecular basis of FH has not been characterized, thus, the aim of this study was to investigate mutations in the exon 4 of the LDLR (LDL-receptor) gene in 225 Venezuelan mixed race individuals (65 hypercholesterolemic and 160 normolipidemic). The exon 4 of the LDLR gene was screened by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) analysis and DNA sequencing. Additionally, ApoB-100 gene mutations were investigated. Different LDLR gene mutations were identified in 5 hypercholesterolemic patients (7.7%), 3 missense mutations (4.6%), and 2 frameshift mutations (3%). All mutations were heterozygous. The missense mutations included the amino acid substitution p.E180K, p.R194S, and p.C152G. The frameshift mutations are caused by insertions resulting in the creation of stop codons: p.D157fsX158 and p.S173fsX174, which could code for truncated LDLR of 157 and 173 amino acids, respectively. The apoB gene mutations were not detected in any of our patients and to our knowledge 4 mutations identified in this study have not been reported previously, this study being the first comprehensive mutation analysis of the LDLR causing FH in our region. The early identification of individuals at risk allows changes in lifestyle, including dietary intervention, followed by drug treatment.

[G138A polymorphism of the RNASEL gene and its association with the development of prostate cancer. Preliminary study]. / Polimorfismo G1385A del gen RNASEL y su asociación con el desarrollo de cáncer de próstata. Estudio preliminar.

Prostate Cancer (CAP), is a complex disease with a multifactorial origin. It is characterized by heterogenous patterns of growth of neoplasic tissue, varying widely in its progression, age of beginning and therapy response. It is considered as the second most common cause of death by cancer in men and, it has been estimated, that one of five, suffers of CAP through the course of his life. The genetic etiology of neoplasic transformation of normal prostate cells is still not known; nevertheless, investigations in epidemiology have demonstrated a strong genetic component in its development, suggesting so much a pattern of mendelian inheritance as the presence of loci of susceptibility throughout the human genome. It has been described a cromosomic location related to the CAP in locus 1q24-25, denominated HPC1, where the gene RNASEL is located, and the seggregation of its alleles has been associated with the development of CAP in numerous familiar groups. The RNASEL gene codifies for a ribonuclease protein that degrades vi-ral and cellular ARN and takes part in the apoptosis. A decrease of the enzymatic activity up to three times in carriers of the G1385A polymorphism of this gene has been reported, and the same has been associated frequently with the development of CAP. Using a variant of the Polymerase Chain Reaction, Allele specific amplification, this investigation had as objective to determine the association between variant G1385A and CAP, in a sample of 103 masculine individuals with and without CAP, pertaining to the population of Maracaibo, Venezuela. An association between these variants and CAP could not be demonstrated.

Polimorfismo G1385A del gen RNASEL y su asociación con el desarrollo de cáncer de próstota: estudio preliminar / G138A polymorphism of the RANASEL gene and its association with the development of prostate cancer: preliminary study

El cáncer de Próstata (CAP), es una enfermedad compleja de origen multifactorial. Se caracteriza por patrones heterogéneos de crecimiento de tejido neoplásico, que varían ampliamente en su progresión, edad de aparición y respuesta al tratamiento. Se considera la segunda causa más común de muerte por malignidad en hombres y se estima que uno de cada cinco padece de CAP en el curso de su vida. La etiología genética de la transformación neoplásica de las células prostáticas normales aún es desconocida, sin embargo, investigaciones epidemiológicas han demostrado un fuerte componente genético en su desarrollo, y sugieren tanto un patrón de herencia mendeliana como la presencia de loci de susceptibilidad a lo largo del genoma humano. Se ha descrito una región cromosómica relacionada con el CAP denominada como HPC1, en el locus 1q24-25, donde se ubica el gen RNASEL, y las mutaciones en el mismo, se han asociado con la presencia del CAP en múltiples grupos familiares. EL gen RNASEL codifica para una ribonucleasa que degrada ARN viral y celular y que interviene en la apoptosis. Se ha reportado disminución de la actividad enzimática de hasta tres veces en portadores del polimorfismo G1385A de este gen, y la misma se ha asociado frecuentemente con el desarrollo del CAP. Mediante la utilización de una variante de la Reacción en Cadena de la Polimerasa (RCP), una amplificación alelo específica, se estudiaron 103 individuos masculinos con y sin CAP pertenecientes a la población de Maracaibo, Venezuela, evidenciándose ausencia de asociación.

Prostate Cancer (CAP), is a complex disease with a multifactorial origin. It is characterized by heterogenous patterns of growth of neoplasic tissue, varying widely in its progression, age of beginning and therapy response. It is considered as the second most common cause of death by cancer in men and, it has been estimated, that one of five, suffers of CAP through the course of his life. The genetic etiology of neoplasic transformation of normal prostate cells is still not known; nevertheless, investigations in epidemiology have demonstrated a strong genetic component in its development, suggesting so much a pattern of mendelian inheritance as the presence of loci of susceptibility throughout the human genome. It has been described a cromosomic location related to the CAP in locus 1q24-25, denominated HPC1, where the gene RNASEL is located, and the seggregation of its alleles has been associated with the development of CAP in numerous familiar groups. The RNASEL gene codifies for a ribonuclease protein that degrades viral and cellular ARN and takes part in the apoptosis. A decrease of the enzymatic activity up to three times in carriers of the G1385A polymorphism of this gene has been reported, and the same has been associated frequently with the development of CAP. Using a variant of the Polymerase Chain Reaction, Allele specific amplification, this investigation had as objective to determine the association between variant G1385A and CAP, in a sample of 103 masculine individuals with and without CAP, pertaining to the population of Maracaibo, Venezuela, An association between these variants and CAP could not be demonstrated.

[Frequency and clinicopathological associations of K-ras mutations in Venezuelan patients with colo-rectal cancer]. / Frecuencia y asociación clínicopatológico de las mutaciones del oncogen K-ras en pacientes venezolanos con cáncer colorectal.

Mutations in the K-ras oncogene are common in colo-rectal cancer, which affect the biological behaviour and may influence the susceptibility to therapy in these tumors. The objective of this work was to identify the types of K-ras mutations observed in referred patients with colo-rectal cancer and to relate them to their degree of histological differentiation and clinical stage. Histopathological and clinical data were obtained from medical records. DNA was obtained from both, fresh tissue and tumor tissue embedded in paraffin. The K-ras gene was amplified through the polymerase chain reaction (PCR) and the amplified fragments were digested with restriction enzymes. We found mutations in codons 12 and 13 of the K-ras oncogene in 23.33% of patients. Of these, 28.57% were located at codon 12, 57.14% were at codon 13 and 14.29% at both codons. They were more frequent in tumors located in the left hemicolon and, according to their histological type, were more frequent in well differentiated adenocarcinomas (58.70%) and in mucinous (28.57%). The identified mutations were more frequent in advanced stages (C2) of Dukes' classification. The molecular analysis of the K-ras oncogene made mutations evident, which could be useful in the diagnosis and prognosis of colorectal tumors. The frequency of mutations found in this work is similar to some of those reported worldwide; however, they differ in the more frequent type of mutation, which, in our study, was located at codon 13 in more than 50% of the cases.

Identificación de especies en productos de origen animal mediante PCR / PCR-species-identication in animal products

La identificación de la especie en productos de origen animal (carne, leche o sus derivados) se hace necesaria y de exigencia por los consumidores modernos, entre otras razones: i) para evitar fraude económico, ya sea por sustitución o adulteración del mismo, ii) por motivos de salud humana, tales como alergias alimentarías, iii) por implicaciones culturales; de allí que se debe contar con herramientas analíticas y sensibles para dicha identificación tales como el análisis de fragmentos de ADN en especial de origen mitocondrial (gen 12S ARNr) dada su particularidad de ser especifica de especies. A tal fin se estableció una metodología de identificación mediante la amplificación de fragmentos específicos de ADN mitocondrial (ADNm) a partir de muestras biológicas de las principales especies animales implicadas en la producción de carnes o alimentos (bovina, porcina, ovina, caprina, equina, asnos, felina y canina), específicamente de una fracción parcial del gen 12sARNr de una región conservada usando unos cebadores comunes para dichas especies, un “reverse” especifico de especie y análisis posterior mediante geles de agarosa al 1,5 por ciento y amplificación de fragmentos que oscilaron entre 150 y 364 pb. Los resultados indican que se puede identificar la especie a la que pertenece la muestra analizada en el 100 por ciento de los casos, ofreciendo una herramienta especifica para determinar la especie en alimentos de origen animal.

Nowadays identification of animal-origin products (meat, milk and dairy products) is of paramount importance to costumers and specially as for species identification for a number of reasons: i) to avoid economic fraud for substitution or alteration of the product ; ii) to avoid health issues such as food allergies; iii) for culturals reasons. There for the value of analytic and sensitive identification tools such as DNA fragments analysis, especially those of mitochondrial origin (12S rRNA gene) because of its species-specific character. An identification methodology through amplification of a species-conserved region of 12S rRNA gene (forward primer) and of a species-specific region of the same gene (reverse primer). Template DNA was extracted from biological samples of bovine, swine, ovine, caprine, equine and canine origin. After 1.5 percent agarose gel electrophoresis, fragments ranging from 150 to 364 bp were observed. Results show that species could be easily identified through PCR in all cases and that this methodology could be a specific tool for determining the origin of animal products.

Frecuencia y asociación línicopatológico de las mutaciones del oncogen K-ras en pacientes venezolanos con cáncer colorectal / Frequency and clinicopathological associations of K-ras mutations in Venezuelan patients with colo-rectal cancer

Las mutaciones en el oncogén K-ras son comunes en cáncer colo-rectal, afectan el comportamiento biológico y podrían influir en la susceptibilidad terapéutica en estos tumores. El objetivo de este trabajo fue identificar los tipos de mutación K-ras observados en pacientes referidos con cáncer colo-rectal y relacionarlos con el grado de diferenciación histológica y con el estadio clínico. Se obtuvo ADN genómico tanto de tejido tumoral incluido en parafina, como de tejido fresco. Se amplificó el gen K-ras a través de la reacción en cadena de la polimerasa (RCP) y se digirieron los fragmentos amplificados con enzimas de restricción, por último se obtuvieron datos clínicos e histopatológicos de las historias clínicas. Se encontraron mutaciones en los codones 12 y 13 del oncogén K-ras en el 23,33% de los pacientes. De estos 28,57% en el codón 12, en el codón 13 se encontró un 57,14% y 14,29% para ambos codones. Fueron más frecuentes en el hemicolon izquierdo con 78,57% y según la clasificación histológica en los adenocarcinomas bien diferenciados (58,70%) y en los mucinosos (28,57%). Las mutaciones identificadas fueron mas frecuentes en estadios avanzados C2 de la clasificación de Dukes`. El análisis molecular del oncogén K-ras permitió evidenciar mutaciones que sirven como parámetro diagnóstico y pronóstico en los tumores colo-rectales. La frecuencia de mutaciones encontradas en este trabajo es similar a algunas de las reportadas a nivel mundial, sin embargo difieren en el tipo de mutación mas frecuente, que en nuestro medio fue la mutación del codón 13 del gen con más de un 50%.

Mutations in the K-ras oncogene are common in colo-rectal cancer, which affect the biological behaviour and may influence the susceptibility to therapy in these tumors. The objective of this work was to identify the types of K-ras mutations observed in referred patients with colo-rectal cancer and to relate them to their degree of histological differentiation and clinical stage. Histopathological and clinical data were obtained from medical records. DNA was obtained from both, fresh tissue and tumor tissue embedded in paraffin. The K-ras gene was amplified through the polymerase chain reaction (PCR) and the amplified fragments were digested with restriction enzymes. We found mutations in codons 12 and 13 of the K-ras oncogene in 23.33% of patients. Of these, 28.57% were located at codon 12, 57.14% were at codon 13 and 14.29% at both codons. They were more frequent in tumors located in the left hemicolon and, according to their histological type, were more frequent in well differentiated adenocarcinomas (58.70%) and in mucinous (28.57%). The identified mutations were more frequent in advanced stages (C2) of Dukes’ classification. The molecular analysis of the K-ras oncogene made mutations evident, which could be useful in the diagnosis and prognosis of colorectal tumors. The frequency of mutations found in this work is similar to some of those reported worldwide; however, they differ in the more frequent type of mutation, which, in our study, was located at codon 13 in more than 50% of the cases.

[Association of the vitamin D receptor gene BBAAtt haplotype with osteoporosis in post-menopausic women]. / Asociación del haplotipo BBAAtt del gen del receptor de la vitamina D con la osteoporosis en mujeres posmenopáusicas.

Osteoporosis (OP) is an important public issue affecting more than 150 millions all over the world, mainly post-menopausic women. Epidemiological studies have shown that the genetic factors could be involved in 80-90% of the bone mineral density variabiblity and therefore, related to the risk of OP manifestations. The vitamin D receptor (VRD) gene has been extensively studied, but its relationship with OP has been controversial. The aim of this investigation was to study the association of Bsm I, Apa I and Taq I VDR gene polymorphism with OP in 147 post-menopausic women; 71 with OP and 76 without the disease (control). The molecular gene analysis was performed using the polymerase chain reaction (PCR). The genotypes BB, AA, and tt were found in 56.33, 50.70 and 25.35% and in 21.05, 28.95 and 10.53% of OP patients and controls respectively. The haplotype BBAAtt was observed in 23.94% of OP patients and 5.26% of the controls. This haplotype was a risk factor for OP, since a odds ratio (OR) of 5.66 was found, while, haplotype BbaaTT was a protection factor (OR: 0.10). These findings support the association of the vitamin D receptor gene BBAAtt haplotype with OP.

Asociación del haplotipo BBAAtt del gen del receptor de la vitamina D con la osteoporosis en mujeres posmenopáusicas / Association of the vitamin D receptor gene BBAAtt haplotype with osteoporosis in post-menopausic women

La Osteoporosis (OP) es un problema de salud pública, que afecta a más de 150 millones de personas en el mundo, mayoritariamente mujeres posmenopáusicas. Estudios epidemiológicos demuestran que los factores genéticos podrían representar el 80-90 por ciento de la variabilidad en la densidad mineral ósea y en consecuencia relacionarse con el riesgo a sufrir OP. El gen del receptor de la vitamina D (RVD) se ha estudiado ampliamente en este campo y su relación con la osteoporosis ha sido controversial. El objetivo de esta investigación fue estudiar la asociación de los polimorfismos Bsm I, Apa I y Taq I del gen del RVD con la OP en 147 mujeres posmenopáusicas, 71 con OP y 76 sin la enfermedad (control). El análisis molecular se realizó utilizando la reacción en cadena de la polimerasa (RCP). Los genotipos BB, AA y tt se encontraron en 56,33, 50,70 y 25,35 por ciento y en 21,05, 28,95 y 10,53 por ciento, en el grupo con OP y control, respectivamente. El haplotipo BBAAtt se observó en un 23,94 por ciento en el grupo con OP y en 5,26 por ciento en el grupo control. Este haplotipo resultó ser factor de riesgo para la OP con Razón de disparidad (RD) de 5,66, mientras que el haplotipo BbaaTT, factor de protección (RD: 0,10). Estos hallazgos apoyan la asociación del haplotipo BBAAtt del gen del receptor de la vitamina D con la OP.

Usefulness of 12 Y-STRs for forensic genetics evaluation in two populations from Venezuela.

The distribution of allele frequencies and haplotypes for 12 STRs loci, (DYS19, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DYS385a/b, DYS437, DYS438 and DYS439) on the Y-chromosome from two Venezuelan populations were determined in 173 DNA samples of unrelated males living in Caracas (62) and Maracaibo (111). Some parameters of forensic importance were calculated. AMOVA and genetic distances between these populations were estimated. The results confirmed Y-STR genotypes as useful markers for forensic genetics analysis.