Abstract Background: The presence of clinically relevant mutations in KRAS and NRAS genes determines the response of anti-epidermal growth factor receptor antibody therapy for metastatic colorectal cancer (mCRC). The only quantitative polymerase chain reaction (qPCR)-based diagnostic tests approved by the Food and Drug Administration (FDA) screen merely for mutations in codons 12 and 13 of KRAS. Objective: The objective of the study was to study the frequency of clinically relevant mutations in KRAS and NRAS genes that are not included in FDA-approved qPCR tests. Methods: Formalin-fixed paraffin-embedded tumor specimens from 1113 mCRC Mexican patients from different health institutions across the country were analyzed by Sanger sequencing for KRAS mutations in exons 2, 3, and 4. Furthermore, 83 were analyzed in exons 2, 3, and 4 of NRAS. Results: From the specimens tested for KRAS, 33.69% harbored a mutation. From these, 71.77% were in codon 12 and 27.69% in codon 13 (both located in exon 2). Codons 59 (exon 3) and 146 (exon 4) accounted for the remaining 0.54%. From the 83 specimens, in which NRAS was analyzed, three mutations were found in codon 12 (3.61%). Approximately 6% of RAS mutated specimens would have been falsely reported as RAS wild type if an FDA-approved qPCR diagnostic test had been used. Conclusions: While these kits based on qPCR can be very practical and highly sensitive, their mutation coverage ignores mutations from poorly genetically characterized populations.

BACKGROUND: Chemerin, encoded by the retinoic acid receptor responder 2 (RARRES2) gene is an adipocytesecreted protein with autocrine/paracrine functions in adipose tissue, metabolism and inflammation with a recently described function in vascular tone regulation, liver, steatosis, etc. This molecule is believed to represent a critical endocrine signal linking obesity to diabetes. There are no data available regarding evolution of RARRES2 in non-human primates and great apes. Expression profile and orthology in RARRES2 genes are unknown aspects in the biology of this multigene family in primates. Thus; we attempt to describe expression profile and phylogenetic relationship as complementary knowledge in the function of this gene in primates. To do that, we performed A RT-PCR from different tissues obtained during necropsies. Also we tested the hypotheses of positive evolution, purifying selection, and neutrality. And finally a phylogenetic analysis was made between primates RARRES2 protein. RESULTS: RARRES2 transcripts were present in liver, lung, adipose tissue, ovary, pancreas, heart, hypothalamus and pituitary tissues. Expression in kidney and leukocytes were not detectable in either species. It was determined that the studied genes are orthologous. CONCLUSIONS: RARRES2 evolution fits the hypothesis of purifying selection. Expression profiles of the RARRES2 gene are similar in baboons and chimpanzees and are also phylogenetically related.

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. > 3, OR 2.1), an early age of first intercourse (IVS) (17 < vs. > 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, TVS and MTHFR polymorphisms (presence of 1298C allele or 677TT genotype) was observed. The 1298C allele plus multipregnancies and IVS < 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.

Objetivo. Buscar la asociación entre polimorfismos de la enzima metilentetrahidrofolato reductasa (MTHFR), factores ambientales y cáncer cérvico-uterino (CaCU) en mujeres del noreste de México. Métodos. Setenta pacientes con CaCU y 89 mujeres controles se sometieron a un interrogatorio clínico y a genotipificación de los polimorfismos 677C<img border=0 id="_x0000_i1025" src="../../../../../img/revistas/ric/v58n5/a7s1.jpg">T y 1298A<img border=0 id="_x0000_i1026" src="../../../../../img/revistas/ric/v58n5/a7s1.jpg">C del gen MTHFR. Resultados. La multigestación (0-2 vs.> 3, OR 2.1), un temprano inicio de vida sexual (IVS) (17 < vs. > 18 años, OR 4.3) o la combinación de ambos factores (OR 3.5), estuvieron asociados significativamente al CaCU. Los polimorfismos de MTHFR 677, 1298 y sus combinaciones no fueron diferentes entre casos y controles. Sin embargo, se observó una interacción significativa entre las gestaciones, el IVS y los polimorfismos de MTHFR (presencia del alelo 1298C o del genotipo 677TT). El alelo 1298C combinado con multigestación, con un IVS < 17 años, o con ambos factores, incrementó el riesgo para CaCU en 4.3, 5.3 y 11.8 veces, respectivamente, en tanto que el genotipo 677TT modificó este riesgo a 2.0, 1.9, y 4.2 veces, respectivamente. Conclusión. El alelo 1298C incrementa considerablemente el riesgo para CaCU en mujeres multigestas y con un IVS temprano, en tanto que el genotipo 677TT disminuye este riesgo, pero sin llegar a convertirse en un factor protector.

OBJECTIVE: To investigate the association between family history (FH) of neoplasia, gyneco-obstetric factors and breast cancer (BC) in a case--control study. In cases, to analyze those variables in relation with early onset of BC, the manner of detection (self-examination, prompted by pain, or casual), the size of tumor, and the elapsed time to seek medical attention. MATERIAL AND METHODS: Data from 151 prevalent BC cases and 235 age-matched controls were analyzed by multiple logistic regression, to assess the influence of BC risk factors. RESULTS: Ten per cent of patients and 1% of controls had first-degree relatives (FDR) with BC. Family history of FDR with BC (OR, 11.2; 95% CI 2.42-51.92) or with gastric or pancreatic cancer (OR, 17.7; 95% CI 2.2-142.6) was associated with BC risk. Breastfeeding at or under 25 years of age was protective against BC (OR, 0.40; 95% CI 0.24-0.66). The manner of tumor detection did not influence its size at the time of diagnosis. CONCLUSIONS: Our study confirms that FH of BC and/or of gastric or pancreatic carcinoma are risk factors for BC, while lactation at 25 years of age or earlier is protective.

OBJETIVO: Investigar la asociación entre la historia familiar de neoplasias, factores ginecobstétricos y cáncer mamario (CM) en un estudio de casos y controles. Además, en los casos, estudiar estas variables en relación con inicio temprano del cáncer, forma de detección (autoexamen, exploración individual por dolor o casual), tamaño del tumor. MATERIAL E MÉTODOS: Entre enero y marzo de 1997 se estudiaron 151 casos prevalentes de CM y 235 controles pareados por edad provenientes del Hospital de Especialidades del Centro Médico del Noreste, Instituto Mexicano del Seguro Social, o del Hospital Universitario de la Universidad Autónoma de Nuevo León, ambos localizados en Monterrey, México. Los factores de riesgo se analizaron con regresión logística múltiple. RESULTADOS: Diez por ciento de casos y 1% de controles tuvieron historia familiar de primer grado para CM; este antecedente (razón de momios --RM, 11.2; IC 95%; 2.42-51.92) y el de carcinoma gástrico o pancreático (RM, 17.7; IC 95%; 2.2-142.6) se asociaron con riesgo de CM. El amamantar a los 25 años o menos fue factor protector (RM, 0.40; IC 95%; 0.24-0.66). La forma de detección del tumor no influyó en el tamaño del tumor al momento del diagnóstico. CONCLUSIONES: Se mostró que la historia familiar de CM y de carcinoma gástrico o pancreático son factores de riesgo para CM, mientras que la lactancia a los 25 años o antes, es protectora.