Browsing by Author "Carvallo, P"

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    Determination of a BRCA1 gene mutation in a family with hereditary breast cancer
    (SOC MEDICA SANTIAGO, 2004) Gallardo, M; Faundez, P; Cruz, A; Rodriguez, M; Alvarez, M; Carvallo, P
    Background: Breast cancer is the main cause of death among fore, the women between 40 and 55 years old, in whom the hereditary cases are common. Therefore molecular diagnosis of germ line initiations involved in breast cancer susceptibilily is relevant. BRCA1 and BRCA2 have been described as the two major genes involved in familial breast/ovarian cancer. We are performing a screening for BRCA 1 and BRCA2 genes, in a group of 50 high risk Chilean families for breast/ovarian cancer. We have detected a mutation, 3936 C > T, that leads to a truncated protein, in two affected women from one of the families in study.
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    Incidence of BRCA1 and BRCA2 mutations in 54 Chilean families with breast/ovarian cancer, genotype-phenotype correlations
    (2006) Gallardo, M; Silva, A; Rubio, L; Alvarez, C; Torrealba, C; Salinas, M; Tapia, T; Faundez, P; Palma, L; Riccio, M; Paredes, H; Rodriguez, M; Cruz, A; Rousseau, C; King, M; Camus, M; Alvarez, M; Carvallo, P
    Our aim was to analyze the incidence of mutations in BRCA1 and BRCA2 genes in 54 families with breast/ovarian cancer. Families were selected from three Institutions following the standard criteria for hereditary breast/ovarian cancer. PCR amplification of all exons was performed, followed by SSCP, heteroduplex, PTT and sequencing analysis. We identified eight truncation mutations, three in the BRCA1 gene and five in the BRCA2 gene. Three of these mutations have not been reported previously by other groups: 308insA in one family, 3936 C > T in two families, for BRCA1, and 4970insTG in one family for BRCA2. In addition two families having Ashkenazi Jewish ancestors present the well known mutations 185delAG and 6174delT. Interestingly, 5 out of 11 families have mutations recurrent in Spanish families. Among the 54 families selected, seven have breast and ovary cancer cases, and only two presented a mutation in BRCA1 or BRCA2 genes. Other cancers as prostate and stomach are frequent among relatives carrying the mutation. Five cases of very early onset (< 31 years old) breast cancer were detected. The frequencies of BRCA1 (0.074) and BRCA2 (0.13) mutations in our families is low but similar to the incidence found in other populations, like in Spain. Since is widely known that risk factors that modulate the development of breast cancer such as lifestyle risk factors, geographic location, country of origin and socioeconomic status, besides a familial history of breast cancer our findings suggest that the history of colonization and immigrations is very relevant when studying hereditary factors associated to breast cancer.
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    Mitochondrial DNA polymorphisms in Chilean aboriginal populations: Implications for the peopling of the southern cone of the continent
    (WILEY, 2000) Moraga, ML; Rocco, P; Miquel, JF; Nervi, F; Llop, E; Chakraborty, R; Rothhammer, F; Carvallo, P
    The mitochondrial DNAs (mtDNAs) from individuals belonging to three Chilean tribes, the Mapuche, the Pehuenche, and the Yaghan, were studied both by RFLP analysis and D-loop (control region) sequencing. RFLP analysis showed that 3 individuals (1.3%) belonged to haplogroup A, 19 (8%) to haplogroup B, 102 (43%) to haplogroup C, and 113 (47.7%) to haplogroup D. Among the 73 individuals analyzed by D-loop sequencing we observed 37 different haplotypes defined by 52 polymorphic sites. Joint analysis of data obtained by RFLP and sequencing methods demonstrated that, regardless of the method of analysis, the mtDNA haplotypes of these three contemporary South American aborigine groups clustered into four main haplogroups, in a way similar to those previously described for other Amerindians. These results further revealed the absence of haplogroup A in both the Mapuche and Yaghan as well as the absence of haplogroup B in the Yaghan. These results suggest that the people of Tierra del Fuego are related to tribes from south-central South America. (C) 2000 Wiley-Liss, Inc.
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    Origin and evolutionary relationships of native Andean populations
    (2001) Rothhammer, F; Llop, E; Carvallo, P; Moraga, M
    This paper represents an effort to explore the origin and the evolutionary relationships of native Andean populations using a multidisciplinary approach. Archeological and linguistic evidence is briefly reviewed. A genetic distance analysis among major linguistic groupings and among Andean and Amazonian native populations, together with information obtained from archaeological and linguistic sources was used to generate a migration model. It is suggested that in the late Pleistocene a group of nomadic hunters entered South America through the Isthmus of Panama and split afterwards into two groups, one moving southward into the central and south Andean areas and after crossing the Colombian, Equador and Peruvian highlands to people northwestern Argentina, the open park country of east Brazil and the Argentine Pampas. The second group migrated eastwards into Venezuela and Guyana and later southward, peopling the Brazilian Amazon. Following available waterways the Amazonian Indians expanded east and west arriving probably at the eastern slopes of the Andes some 3,500 years ago. It is hypothesized that present day Andean natives are descendants of the Amazonian groups that migrated eastwards.
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    Study of GH sensitivity in Chilean patients with idiopathic short stature
    (ENDOCRINE SOC, 2001) Sjoberg, M; Salazar, T; Espinosa, C; Dagnino, A; Avila, A; Eggers, M; Cassorla, F; Carvallo, P; Mericq, MV
    We hypothesized that some children with idiopathic short stature in Chile might bear heterozygous mutations of the GH receptor. We selected 26 patients (3 females, 23 males) from 112 patients who consulted for idiopathic short stature at the University of Chile. Their chronological age was 8.3 +/-1.9, and bone age was 6.1 +/-1.0 yr. Their height was -3.0 +/-0.7 SDS; IGF-I, -1.2 +/-1.1 SD; IGF binding protein 3, -0.7 +/-2.0 SDS; and GH binding protein, 0.4 +/-0.8 SDS. Patients were admitted, and blood samples were obtained every 20 min to determine GH concentrations overnight. Coding sequences and intron-exon boundaries of exons 2-10 of GH receptor gene were amplified by PCR and subsequently analyzed through single-strand conformational analysis. Mean serum GH concentration, over 12-h, was 0.20 +/-0.08 nm; pulse amplitude, 0.40 +/-0.15 nM; number of peaks, 5.8 +/-1.5 peaks/12 h; peak value of GH during the 12-h sampling, 1.03 +/-0.53 nm; and area under the curve, 151.4 +/- 56.1 nM/12 h. There were positive correlations between mean GH vs. area under the curve (P<0.001) and GH peak (P<0.01). The single-strand conformational analysis of the GH receptor gene showed abnormal migration for exon 6 in 9 patients and for exon 10 in 9 patients, which (by sequence analysis) corresponded to 2 polymorphisms of the GH receptor gene: an A-to-G transition in third position of codon 168 in exon 6 and a C-to-A transversion in the first position of codon 526 in exon 10. We further sequenced all coding exons and intron-exon boundaries in the most affected patients (nos. 6, 9, 11, 14, 15, 16, and 23). This analysis revealed a C-to-T transition in codon 161 of exon 6 in patient 23, which results in an amino acid change (Arg to Cys) in an heterozygous form in the patient and his father. In conclusion, the results of our study suggest that, in Chilean patients with idiopathic short stature, GH receptor gene mutations are uncommon, although we cannot exclude mutations that were missed by single-strand conformational analysis or mutations within introns or in the promoter regions of the GH receptor gene.