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Next-generation sequencing (NGS) is progressively being used in clinical practice. However, several barriers preclude using this technology for precision oncology in most Latin American countries. To overcome some of these barriers, we have designed a 25-gene panel that contains predictive biomarkers for most current and near-future available therapies in Chile and Latin America. Library preparation was optimized to account for low DNA integrity observed in formalin-fixed paraffin-embedded tissue. The workflow includes an automated bioinformatic pipeline that accounts for the underrepresentation of Latin Americans in genome databases. The panel detected small insertions, deletions, and single nucleotide variants down to allelic frequencies of 0.05 with high sensitivity, specificity, and reproducibility. The workflow was validated in 272 clinical samples from several solid tumor types, including gallbladder (GBC). More than 50 biomarkers were detected in these samples, mainly in BRCA1/2, KRAS, and PIK3CA genes. In GBC, biomarkers for PARP, EGFR, PIK3CA, mTOR, and Hedgehog signaling inhibitors were found. Thus, this small NGS panel is an accurate and sensitive method that may constitute a more cost-efficient alternative to multiple non-NGS assays and costly, large NGS panels. This kind of streamlined assay with automated bioinformatics analysis may facilitate the implementation of precision medicine in Latin America.

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BACKGROUND AND AIMS: Gallbladder cancer (GBC) is a neglected disease with substantial geographical variability: Chile shows the highest incidence worldwide, while GBC is relatively rare in Europe. Here, we investigate the causal effects of risk factors considered in current GBC prevention programs as well as C-reactive protein (CRP) level as a marker of chronic inflammation. APPROACH AND RESULTS: We applied two-sample Mendelian randomization (MR) using publicly available data and our own data from a retrospective Chilean and a prospective European study. Causality was assessed by inverse variance weighted (IVW), MR-Egger regression, and weighted median estimates complemented with sensitivity analyses on potential heterogeneity and pleiotropy, two-step MR, and mediation analysis. We found evidence for a causal effect of gallstone disease on GBC risk in Chileans (P = 9 × 10-5 ) and Europeans (P = 9 × 10-5 ). A genetically elevated body mass index (BMI) increased GBC risk in Chileans (P = 0.03), while higher CRP concentrations increased GBC risk in Europeans (P = 4.1 × 10-6 ). European results suggest causal effects of BMI on gallstone disease (P = 0.008); public Chilean data were not, however, available to enable assessment of the mediation effects among causal GBC risk factors. CONCLUSIONS: Two risk factors considered in the current Chilean program for GBC prevention are causally linked to GBC risk: gallstones and BMI. For Europeans, BMI showed a causal effect on gallstone risk, which was itself causally linked to GBC risk.

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BACKGROUND: The first large-scale genome-wide association study of gallbladder cancer (GBC) recently identified and validated three susceptibility variants in the ABCB1 and ABCB4 genes for individuals of Indian descent. We investigated whether these variants were also associated with GBC risk in Chileans, who show the highest incidence of GBC worldwide, and in Europeans with a low GBC incidence. METHODS: This population-based study analysed genotype data from retrospective Chilean case-control (255 cases, 2042 controls) and prospective European cohort (108 cases, 181 controls) samples consistently with the original publication. RESULTS: Our results confirmed the reported associations for Chileans with similar risk effects. Particularly strong associations (per-allele odds ratios close to 2) were observed for Chileans with high Native American (=Mapuche) ancestry. No associations were noticed for Europeans, but the statistical power was low. CONCLUSION: Taking full advantage of genetic and ethnic differences in GBC risk may improve the efficiency of current prevention programs.

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Porphyria cutanea tarda (PCT) is the most common type of porphyria: it is characterized by blistering lesions, erosions and crusts on the back of the hands, associated with photosensitivity and facial hypertrichosis. It is produced by acquired or hereditary deficiency of the enzyme UROD, fifth enzyme in the chain of production of the Heme group. This causes accumulation of porphyrins in the liver, which are subsequently mobilized to the skin, where lesions are generated by photosensitivity. This deficiency can be exacerbated by multiple causes. We report a 51-year-old female presenting with the characteristic dermal lesions described above, which disappeared when she discontinued her hormone replacement therapy with estradiol and dydrogesterone. Urinary and blood uroporphyrin and hexacarboxyl porphyrins were elevated and plasma ferritin was 479 ng/ml. Hormone replacement therapy was discontinued and phlebotomies were attempted but not tolerated by the patient. The dermic lesions have not relapsed.

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Introducción: La morfea o esclerodermia localizada juvenil (ELJ) es una enfermedad autoinmune, inflamatoria, crónica, lenta y progresiva del tejido conectivo, de causa desconocida, que afecta preferentemente la piel y los tejidos subyacentes. Objetivos: Comunicar un caso de esclerodermia localizada juvenil en una escolar, y contribuir a un diagnóstico y tratamiento oportuno de esta patología. Caso clínico: Niña de 8 años con placas induradas hipopigmentadas, de distribución lineal en la extremidad superior derecha de 2 años de evolución y placas induradas hiperpigmentadas de textura acartonada, con áreas de piel adelgazada, blanquecina y edema en la pierna y el tobillo. Los elementos clínicos y los exámenes de apoyo diagnóstico, incluyendo la histología, fueron compatibles con ELJ lineal, panesclerótica. Se inició tratamiento inmunosupresor y simultáneamente realizó fisioterapia y terapia ocupacional intensivas. Conclusiones: Presentamos un caso de ELJ de tipo lineal y panesclerótico, en el que hubo retraso de 2 años en el diagnóstico, no obstante la respuesta al tratamiento inmunosupresor fue favorable según lo esperado.

Introduction: Morphea or juvenile localised scleroderma (JLS) is an autoimmune, inflammatory, chronic, slowly progressive connective tissue disease of unknown cause that preferably affects skin and underlying tissues. Objective: To report a case of Juvenil Localised scleroderma in an 8-year old girl, contributing to an early diagnosis and treatment. Clinical case: The case is presented of an 8 year-old girl who presented with indurated hypopigmented plaques, of linear distribution in the right upper extremity of two years onset, together with papery texture hyperpigmented indurated plaques with whitish areas of thinned skin in right lower extremity, and leg and ankle swelling. The clinical features and diagnostic tests, including histology were compatible with linear and pansclerotic JLS. She started with immunosuppressive therapy, physiotherapy, and occupational therapy. Conclusions: We report a case of linear and pansclerotic ELJ type, in which there was a 2 year delay in diagnosis, however the response to treatment was positive as expected.

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INTRODUCTION: Morphea or juvenile localised scleroderma (JLS) is an autoimmune, inflammatory, chronic, slowly progressive connective tissue disease of unknown cause that preferably affects skin and underlying tissues. OBJECTIVE: To report a case of Juvenil Localised scleroderma in an 8-year old girl, contributing to an early diagnosis and treatment. CLINICAL CASE: The case is presented of an 8 year-old girl who presented with indurated hypopigmented plaques, of linear distribution in the right upper extremity of two years onset, together with papery texture hyperpigmented indurated plaques with whitish areas of thinned skin in right lower extremity, and leg and ankle swelling. The clinical features and diagnostic tests, including histology were compatible with linear and pansclerotic JLS. She started with immunosuppressive therapy, physiotherapy, and occupational therapy. CONCLUSIONS: We report a case of linear and pansclerotic ELJ type, in which there was a 2 year delay in diagnosis, however the response to treatment was positive as expected.

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BACKGROUND: PTEN is a tumor suppressor gene that regulates the PTEN/PI3k/AKT/mTOR pathway, which is frequently altered in human cancers including gallbladder cancer (GBC). To determine the frequency of PTEN expression in GBC and to establish its relation to clinical and morphological parameters and survival in GBC. METHODS: The immunohistochemical expression of PTEN was studied in 108 GBC. All the cases included areas of non-tumor mucosa adjacent to the tumor. RESULTS: The group was comprised of 108 patients, 91 women (84.3%) and 17 men (15.7%) with an average age of 65.2 years (SD ± 12.3 years). Thirty-five cases (33%) were early carcinomas (EC) and the remaining 73 (67%) were advanced cases (AC). All the internal controls were positive (moderate or intense in 96.3%). Only in three AC (4.1%) was there a complete absence of PTEN immunohistochemical expression. There were no significant differences in relation between PTEN expression and tumor infiltration or degree of differentiation. The three patients with PTEN inactivation died before 10 months; however, the other patients with AC had a survival of 53% at 10 months. DISCUSSION: Loss of PTEN expression was observed in 4.1% of the advanced GBC. All the patients with this alteration died before 10 months. PTEN inactivation could be a rare event, but with a poor prognosis in advanced GBC.

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BACKGROUND: The HER2/neu gene is a proto-oncogene that can predict the response to treatment with trastuzumab, pertuzumab, and lapatinib. This study was conducted to determine the frequency of HER2/neu overexpression and to identify a subgroup of patients with gallbladder cancer who would benefit from targeted therapy. METHODS: Patients with gallbladder cancer (n = 187; 165 women and 22 men) with a recorded follow-up of at least 5 years were included, along with control subjects (n = 75). An automated immunohistochemical technique was used with an anti-ErbB2 antibody. Scoring was conducted according to the CAP/ASCO (College of American Pathologists/American Society of Clinical Oncology) criteria for breast cancer. RESULTS: Overexpression of HER2/neu was observed in 12.8% of the cases. Of those, 0% were mucosal, 14.3% muscular, 12.8% subserosal, and 10.6% serosal. In 20% of the cases, equivocal staining was observed. Overexpression was more frequent in the advanced cancers and in the better differentiated tumors (13.8% and 17.4%, respectively), but the difference was nonsignificant. The patients with overexpression of HER2/neu had a worse overall survival, when compared with those who had no expression at 5 years (34% vs. 41%). CONCLUSION: This is the single largest study of HER2/neu expression in gallbladder cancer to use commonly accepted scoring criteria. The results indicate that HER2/neu overexpression occurred in 14% of the advanced gallbladder cancer cases. This subgroup may benefit from inhibitors of the HER2/neu pathway.

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Background: The quality of the archival samples stored at pathology services could be a limiting factor for molecular biology studies. Aim: To determine the quality of DNA extracted from gallbladder cancer samples at different institutions. Material and Methods: One hundred ninety four samples coming from fve medical centers in Chile, were analyzed. DNA extraction was quantifed determining genomic DNA concentration. The integrity of DNA was determined by polymerase chain reaction amplification of different length fragments of a constitutive gene (β-globin products of 110, 268 and 501 base pairs). Results: The mean DNA concentration obtained in 194 gallbladder cancer samples was 48 ± 43.1 ng/µl. In 22% of samples, no amplification was achieved despite obtaining a mean DNA concentration of 58.3 ng/ul. In 81, 67 and 22% of samples, a DNA amplification of at least 110, 268 or 501 base pairs was obtained, respectively. No differences in DNA concentration according to the source of the samples were demonstrated. However, there were marked differences in DNA integrity among participating centers. Samples from public hospitals were of lower quality than those from private clinics. Conclusions: Despite some limitations, in 80% of cases, the integrity of DNA in archival samples from pathology services in our country would allow the use of molecular biology techniques.

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BACKGROUND: Overexpression/amplification of the HER2 gene in advanced gastric cancer is a predictor of response to adjuvant therapy with monoclonal antibodies. AIM: To determine the frequency of HER2 gene overexpression and amplification in advanced gastric cancer. MATERIAL AND METHODS: One hundred nine advanced gastric cancer biopsy specimens, from 76 men and 33 women aged 67 ± 14 and 62 ± 12 years respectively, were selected. Three histological patterns (diffuse, intestinal and mixed) were recognized. Automated immunohistochemistry was performed with monoclonal c-erbB-2 (NCL-356) Novocastra. Fluorescent in situ hybridization (FISH) for HER2 was performed in positive cases. RESULTS: In 39% of cases, immunohistochemical staining was negative. It was 1+, 2+ and 3+ positive in 15, 36 and 11% of cases, respectively. It was positive in 16% and 3% of intestinal type and mixed carcinomas, respectively. It was negative in all diffuse carcinomas. FISH was performed in 39 (2 +) cases and in 11 (3 +) cases. The gene amplification was positive in two (2 +) and 11 (3 +) cases (11.9%). The overall concordance between immunohistochemical staining and in situ hybridization was 85%. CONCLUSIONS: In advanced gastric cancer, HER2 gene overexpression or amplification was observed in 11% and 12% of cases, respectively.

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BACKGROUND: The quality of the archival samples stored at pathology services could be a limiting factor for molecular biology studies. AIM: To determine the quality of DNA extracted from gallbladder cancer samples at different institutions. MATERIAL AND METHODS: One hundred ninety four samples coming from five medical centers in Chile, were analyzed. DNA extraction was quantified determining genomic DNA concentration. The integrity of DNA was determined by polymerase chain reaction amplification of different length fragments of a constitutive gene (ß-globin products of 110, 268 and 501 base pairs). RESULTS: The mean DNA concentration obtained in 194 gallbladder cancer samples was 48 ± 43.1 ng/µl. In 22% of samples, no amplification was achieved despite obtaining a mean DNA concentration of 58.3 ng/ul. In 81, 67 and 22% of samples, a DNA amplification of at least 110, 268 or 501 base pairs was obtained, respectively. No differences in DNA concentration according to the source of the samples were demonstrated. However, there were marked differences in DNA integrity among participating centers. Samples from public hospitals were of lower quality than those from private clinics. CONCLUSIONS: Despite some limitations, in 80% of cases, the integrity of DNA in archival samples from pathology services in our country would allow the use of molecular biology techniques.

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The concomitant presence of a primary gastric adenocarcinoma and a gastrointestinal stromal tumor in the stomach is uncommon. We report a 68-year-old male with an advanced gastric adenocarcinoma. During gastrectomy, a nodular intramural lesion was found. The pathological study, revealed a gastrointestinal stromal tumor, positive form CD117. After six months of follow up, there is no evidence of recurrence of either tumor).

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