Recently, MUTYH mutations have been reported to predispose to the development of polyposis. However, polyposis caused by mutations in MUTYH has been characterized as an autosomal recessive hereditary disease, different from the autosomal dominant pattern observed in polyposis caused by APC mutations. We report a 41-year-old female consulting for anemia. Colonoscopy detected multiple sessile polyps and a cecal carcinoma. The patient was operated and in the surgical piece, the tumor invaded serosa and there was lymph node involvement. Approximately 100 polyps were found. The patient received 5-fluorouracil, as adjuvant therapy. The patient had a sister (of a total of 12 brothers) with a colorectal carcinoma. The genetic study identified a homozygous mutation of the MUTYH gene, called c.340T > C, that produces an amino acid change of tyrosine for histidine called p.Y114H. The sister with colorectal cancer was a heterozygous carrier of this mutation.

Hereditary non-polyposis colorectal cancer (HNPCC) or Lynch Syndrome is an autosomic dominant syndrome involving 596-1096 of colorectal cancer patients. Mutations in MLH1 and MSH2 genes account for most cases. These two genes particípate in the DNA mismatch repair pathway. Therefore mutation carriers show microsatellite instability (MSI) in tumors. This syndrome is characterized by the early development of colorectal cancer (before 50 years) and an increased incidence of cancer in other organs. We report four siblings from a family diagnosed with HNPCC. All of them were subjected to colonic surgery for colorectal cancer Moreover, one patient developed an ampulloma after her colon surgery. The molecular-genetic analysis revealed three brothers with microsatellite instability in the tumor tissue, the absence of the MLH1 protein, and the presence of a germ Une mutation localized in introm 15 ofthe MLH1 gene

The origin of Tiwanaku populations hypothesized on the basis of linguistic and ethnohistorical information is tested using ancient mtDNA extracted from skeletal remains. 18 samples were analyzed of which 13 could be typed for amerindian haplogroups whose distribution (A: 8%, B: 15%, C: 23%, D: 23% y otros 31%) relates genetically the remains from Tiwanaku to extant amazonian and quechua populations. The number of analyzed samples is still to small to allow a subdivision by chronological phases in order to establish more precisely the origin of the Tiwanaku population. Nevertheless, the haplogroup distribution is significantly different from the distribution that characterizes the aymara.

Las hipótesis sobre el origen de las poblaciones que construyeron Tiwanaku basadas en información lingüística y etnohistórica son contrastadas haciendo uso de ADN mitocondrial antiguo, aislado de restos esqueletales. Se analizaron 18 muestras de las cuales 13 rindieron amplificados para los marcadores amerindios. La distribución de haplogrupos (A: 8%, B: 15%, C: 23%, D: 23% y otros 31%) relaciona genéticamente a la población estudiada con grupos amazónicos y quechuas actuales. El número de muestras analizadas no permite aún una subdivisión por fases cronológicas con el objeto de precisar más el origen de las poblaciones Tiwanaku. No obstante, la distribución de haplogrupos es significativamente diferente de aquella que caracteriza a los grupos aymara.

The Amazonian origin of Andean populations, hypothesized on the basis of nuclear genetic markers, is tested using ancient mtDNA extracted from skeletal remains from prehistoric populations of the Azapa valley, northern Chile. Forty two samples were analyzed of which 32 could be typed for Amerindian haplogroups whose distribution (A: 31.2 %, B: 21.9 %, C: 31.2 %, D: 3.1 % and others 12.5 %) relates genetically the prehistoric groups to Amazonian and living Andean populations. The number of samples is still to small to allow a subdivision by chronological phases in order to test hypothesis about the biocultural microevolution of the populations studied

La hipótesis del origen amazónico de las poblaciones andinas basada en el análisis de marcadores genéticos nucleares es contrastada haciendo uso de ADN mitocondrial antiguo aislado de restos esqueletales de poblaciones prehistóricas del Valle de Azapa, Arica, Chile. Se analizaron 42 muestras de las cuales 32 rindieron amplificados para los cuatro marcadores amerindios permitiendo su tipificación. La distribución de haplogrupos (A: 31,2 %, B: 21,9 %, C: 31,2 %, D: 3,1 % y otros 12,5 %) relaciona genéticamente a las poblaciones estudiadas con grupos amazónicos y andinos actuales. El número de muestras analizadas no permite aún una subdivisión por fases cronológicas con el objeto de poner a prueba las hipótesis planteadas por arqueólogos y bioantropológos para explicar la microevolución biocultural de las poblaciones estudiadas