Composición genética de la población chilena: las comunidades rurales de los valles de Elqui, Limarí y Choapa / Genetic composition of Chilean population: rural Chilean communities inhabiting Elqui, Limari and Choapa valleys

Background: The population that inhabits the semiarid Northern zone of Chile arose from ethnic admixture between aborigines, Spanish conquerors and the influx, during the XVII century, of foreign aboriginal workers and a minority of African slaves. Aim: To study the phenotypic frequencies of 15 genetic markers among populations inhabiting valleys in the Northern zone of Chile and to estimate the percentage of indigenous, African and Caucasian admixture in these populations. Material and methods: Throughout five different field works, blood samples were obtained from 120 individuals living in the Elqui valley, 120 individuals living in the Limari valley and 85 living in the Choapa valley. Blood groups, erythrocyte enzymes, plasma proteins and HLA markers were typified. Results: In the populations studied, the contribution of non indigenous genes was low in relation with the time elapsed since the Spanish invasion. The Hardy-Weinberg disequilibrium for MNS system would have microevolutive implications. The admixture percentages in these valleys confirm ethnic and historic information. The variation of the enzyme esterase D is identical to that of other Chilean populations. Conclusions: The phenotypic and genetic frequencies in the three populations studied and different admixture of indigenous genes is inversely proportional to the geographic distance from Santiago, in Central Chile

Análisis de paternidad utilizando cuatro marcadores de DNA amplificados mediante la reacción en cadena de polimerasa / Paternity analysis using 4 DNA markers amplified by polymerase chain reaction

Background: DNA typing in forensic analysis is a useful tool to analyze paternity due to its high discrimination power. Aim: To report the experience of Servicio Medico Legal in Santiago, resolving cases of dubious paternity. Subjects and methods: Four highly polymorphic loci, amplified by polymerase chain reactions, were analyzed in 153 cases of uncertain paternity. The paternity index was calculated for each case. Results: The four genetic markers analyzed provided an exclusion probability of 0.933 for the general population in Santiago. Thirty seven cases were excluded as parents. In 31 cases, the paternity index ranged from 19 to 100, considered as probable paternity and 77 cases had an index of over 100, considered as almost certain paternity. Eight cases had an index between 0.5 and 19, considered as inconclusive. All loci met Hardy-Weinberg expectations and their frequencies were similar to other data from people living in Santiago. Conclusions: The use of these genetic markers proved to be very useful, reliable and with a high exclusion power for paternity analysis

Cáncer gástrico: ¿una entidad etiológica única? / Gastric cancer: a unique etiological entity?

Based on epidemiological, clinical and pathological data, the existence of two etiologic entities, for what is generically considered as gastric carcinoma, is postulated. Environmental factors would be more important in the etiology of the differentiated type of gastric cancer and genetic factors would have a relevant role in the etiology of the undifferentiated type. Geographic, ethnic, environmental and genetic factors participate in the epidemiology of gastric cancer. This review emphasizes the evidences supporting the role of genetic factors in the etiology of undifferentiated gastric cancer. The importance of looking for a shared phenotype among patients with this type of cancer is underscored

Composición genética de la población chilena: los atacameños de la comuna de San Pedro de Atacama / Genetic composition of chilean population: the atacameños from San Pedro de Atacama

This work describes the genetic composition of atacameños from San Pedro de Atacama. The results show that a) the contribution of non-indigenous genes is relatively low, in relation to the spanish inmigration period. b) the Hardy-Weinberg genetics disequilibrium for MNSs system should have biological implications. c) the variant for esterasa D enzyme may be the same found in other chilean populations