Colorectal cancer rates in Latin American countries are less than half of those observed in the United States. Latin Americans are the resultant of generations of an admixture of Native American, European, and African individuals. The potential role of genetic admixture in colorectal carcinogenesis has not been examined. We evaluate the association of genetic ancestry with colorectal neoplasms in 190 adenocarcinomas, 113 sporadic adenomas and 243 age-and sex-matched controls enrolled in a multicentric case-control study in Colombia. Individual ancestral genetic fractions were estimated using the STRUCTURE software, based on allele frequencies and assuming three distinct population origins. We used the Illumina Cancer Panel to genotype 1,421 sparse single-nucleotide polymorphisms (SNPs), and Northern and Western European ancestry, LWJ and Han Chinese in Beijing, China populations from the HapMap project as references. A total of 678 autosomal SNPs overlapped with the HapMap data set SNPs and were used for ancestry estimations. African mean ancestry fraction was higher in adenomas (0.13, 95% confidence interval (95% CI) ¼ 0.11-0.15) and cancer cases (0.14, 95% CI ¼ 0.12-0.16) compared with controls (0.11, 95% CI ¼ 0.10-0.12). Conditional logistic regression analysis, controlling for known risk factors, showed a positive association of African ancestry per 10% increase with both colorectal adenoma (odds ratio (OR) ¼ 1.12, 95% CI ¼ 0.97-1.30) and adenocarcinoma (OR ¼ 1.19, 95% CI ¼ 1.05-1.35). In conclusion, increased African ancestry (or variants linked to it) contributes to the increased susceptibility of colorectal cancer in admixed Latin American population.

61Genética del cáncer de mama ARTÍCULO ORIGINAL Análisis de las mutaciones más frecuentes del gen BRCA1 (185delAG y 5382insC) en mujeres con cáncer de mama en Bucaramanga, Colombia Introducción. El cáncer de mama es un problema de salud pública a nivel mundial y en Santander es la primera causa de morbimortalidad por cáncer en mujeres. Todo cáncer se considera una enfermedad genética y las mutaciones en los genes BRCA confieren un riesgo de 60% a 80% para el cáncer de mama. Este estudio consistió en buscar las dos mutaciones BRCA1 más frecuentes según la base de datos Breast Cancer Core Information. Objetivo. Determinar la presencia de mutaciones específicas (185delAG, exón 2, y 5382insC, exón 20) en el gen BRCA1 en mujeres con cáncer de mama heredo-familiar, atendidas en los diferentes servicios de oncología de Bucaramanga, Colombia. Materiales y métodos. La muestra incluyó 30 pacientes, de las cuales se obtuvo un consentimiento informado, un cuestionario dirigido y sangre venosa para los estudios moleculares. El análisis molecular se realizó mediante PCR-mismatch, para introducir o eliminar sitios de restricción, y digestión enzimática (HinfI o DdeI). Resultados. No se detectaron dos de las mutaciones más frecuentes en el gen BRCA1 en las 30 pacientes estudiadas. Conclusión. Se requieren más estudios en la región que abarquen la tamización de la totalidad del gen BRCA1, para hacer una mayor contribución al conocimiento de la epidemiología molecular del cáncer de mama en Bucaramanga, Santander, Colombia.Palabras clave: neoplasias de la mama/genética, genes relacionados con las neoplasias, genes supresores, genes BRCA1, mutación de línea germinal, predisposición genética a la enfermedad. Mutations in the BRCA1 gene (185delAG and 5382insC) are not present in any of the 30 breast cancer patients analyzed from eastern ColombiaIntroduction. Breast cancer is considered a worldwide public health problem, and, in Santander Province, Colombia, it is the first leading cause of morbidity and mortality by cancer in women. All cancers are considered genetic diseases, and mutations in BRCA (BReast CAncer) genes raises the risk for breast cancer by 60%-80%. The current study searched for the two most frequent BRCA1 mutations reported in the Breast Cancer Core Information database. Objective. The presence of specific mutations (185delAG, exon 2 and 5382insC, exon 20) was determined for the BRCA1 gene in women with familial/hereditary breast cancer. Materials and methods. The sample included 30 female patients using the oncology services in Bucaramanga, eastern Colombia; an informed consent, a questionnaire and a blood sample were obtained from each. The molecular analysis was done with PCR-Mismatch, to detect the insertion or eliminatation of a restriction site, and enzymatic digestion methods (HinfI or DdeI). Results. Two of the most frequent BRCA1 mutations in the international database were not found in the 30 patients studied. Conclusion. Additional mutation screening techniques are necessary involving the entire BRCA1 gen...

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