Latin Americans have a rich genetic make-up that translates into heterogeneous fractions of the autosomal genome in runs of homozygosity (FROH) and heterogeneous types and proportions of indigenous American ancestry. While autozygosity has been linked to several human diseases, very little is known about the relationship between inbreeding, genetic ancestry, and cancer risk in Latin Americans. Chile has one of the highest incidences of gallbladder cancer (GBC) in the world, and we investigated the association between inbreeding, GBC, gallstone disease (GSD), and body mass index (BMI) in 4029 genetically admixed Chileans. We calculated individual FROH above 1.5 Mb and weighted polygenic risk scores for GSD, and applied multiple logistic regression to assess the association between homozygosity and GBC risk. We found that homozygosity was due to a heterogeneous mixture of genetic drift and consanguinity in the study population. Although we found no association between homozygosity and overall GBC risk, we detected interactions of FROH with sex, age, and genetic risk of GSD that affected GBC risk. Specifically, the increase in GBC risk per 1% FROH was 19% in men (p-value = 0.002), 30% in those under 60 years of age (p-value = 0.001), and 12% in those with a genetic risk of GSD above the median (p-value = 0.01). The present study highlighted the complex interplay between inbreeding, genetic ancestry, and genetic risk of GSD in the development of GBC. The applied methodology and our findings underscored the importance of considering the population-specific genetic architecture, along with sex- and age-specific effects, when investigating the genetic basis of complex traits in Latin Americans.

Since 2006, Chile has been implementing a gallbladder cancer (GBC) prevention program based on prophylactic cholecystectomy for gallstone patients aged 35 to 49 years. The effectiveness of this prevention program has not yet been comprehensively evaluated. We conducted a retrospective study of 473 Chilean GBC patients and 2137 population-based controls to develop and internally validate three GBC risk prediction models. The Baseline Model accounted for gallstones while adjusting for sex and birth year. Enhanced Model I also included the non-genetic risk factors: body mass index, educational level, Mapuche surnames, number of children and family history of GBC. Enhanced Model II further included Mapuche ancestry and the genotype for rs17209837. Multiple Cox regression was applied to assess the predictive performance, quantified by the area under the precision-recall curve (AUC-PRC) and the number of cholecystectomies needed (NCN) to prevent one case of GBC at age 70 years. The AUC-PRC for the Baseline Model (0.44%, 95%CI 0.42-0.46) increased by 0.22 (95%CI 0.15-0.29) when non-genetic factors were included, and by 0.25 (95%CI 0.20-0.30) when incorporating non-genetic and genetic factors. The overall NCN for Chileans with gallstones (115, 95%CI 104-131) decreased to 92 (95%CI 60-128) for Chileans with a higher risk than the median according to Enhanced Model I, and to 80 (95%CI 59-110) according to Enhanced Model II. In conclusion, age, sex and gallstones are strong risk factors for GBC, but consideration of other non-genetic factors and individual genotype data improves risk prediction and may optimize allocation of financial resources and surgical capacity.

A strong association between the proportion of indigenous South American Mapuche ancestry and the risk of gallbladder cancer (GBC) has been reported in observational studies. Chileans show the highest incidence of GBC worldwide, and the Mapuche are the largest indigenous people in Chile. We set out to assess the confounding-free effect of the individual proportion of Mapuche ancestry on GBC risk and to investigate the mediating effects of gallstone disease and body mass index (BMI) on this association. Genetic markers of Mapuche ancestry were selected based on the informativeness for assignment measure, and then used as instrumental variables in two-sample Mendelian randomization analyses and complementary sensitivity analyses. Results suggested a putatively causal effect of Mapuche ancestry on GBC risk (inverse variance-weighted (IVW) risk increase of 0.8% per 1% increase in Mapuche ancestry proportion, 95% CI 0.4% to 1.2%, p = 6.7 × 10−5) and also on gallstone disease (3.6% IVW risk increase, 95% CI 3.1% to 4.0%), pointing to a mediating effect of gallstones on the association between Mapuche ancestry and GBC. In contrast, the proportion of Mapuche ancestry showed a negative effect on BMI (IVW estimate −0.006 kg/m2, 95% CI −0.009 to −0.003). The results presented here may have significant implications for GBC prevention and are important for future admixture mapping studies. Given that the association between the individual proportion of Mapuche ancestry and GBC risk previously noted in observational studies appears to be free of confounding, primary and secondary prevention strategies that consider genetic ancestry could be particularly efficient.

Objetivo: Los tumores de ovario borderline (BOT) son un grupo de lesiones neoplásicas de origen epitelial del ovario que presentan características de tumores malignos, pero sin invasión del estroma, y se caracterizan por tener un buen pronóstico. El objetivo del estudio es determinar la concordancia diagnóstica entre biopsia contemporánea y definitiva de los BOT en nuestro centro hospitalario. Método: Se realizó un estudio analítico retrospectivo de corte transversal de las biopsias contemporáneas y definitivas de BOT en la base de datos de anatomía patológica del Hospital Padre Hurtado, entre los años 2010 y 2019. El análisis estadístico de concordancia se realizó mediante test de kappa. Resultados: Se revisaron 4546 informes de biopsias entre los años 2010 y 2019. Se pesquisaron 163 tumores malignos de ovario, de los cuales 69 (42,33%) correspondieron a BOT. De estos, 39 fueron serosos (56,2%), 28 mucinosos (40,57%) y 2 (2,8%) de tipo endometrioide. El resultado de concordancia diagnóstica de BOT seroso es moderada, del 75,71% con un índice de kappa de 0,5143 (p = 0,000), y el de BOT mucinoso es débil, del 65,71% con un índice de kappa de 0,2398 (p = 0,0222). Conclusiones: Los BOT corresponden a un gran porcentaje dentro de los tumores malignos del ovario, siendo el subtipo seroso el más común. La concordancia entre biopsia contemporánea y definitiva es de débil a moderada.

Background A strong association between the proportion of Native American ancestry and the risk of gallbladder cancer (GBC) has been reported in observational studies. Chileans show the highest incidence of GBC worldwide, and the Mapuche are the largest Native American people in Chile. We set out to investigate the causal association between Native American Mapuche ancestry and GBC risk, and the possible mediating effects of gallstone disease and body mass index (BMI) on this association. Methods Markers of Mapuche ancestry were selected based on the informativeness for assignment measure and then used as instrumental variables in two-sample mendelian randomization (MR) analyses and complementary sensitivity analyses. Result We found evidence of a causal effect of Mapuche ancestry on GBC risk (inverse variance-weighted (IVW) risk increase of 0.8% for every 1% increase in Mapuche ancestry proportion, 95% CI 0.4% to 1.2%, p = 6.6×10-5). Mapuche ancestry was also causally linked to gallstone disease (IVW risk increase of 3.6% per 1% increase in Mapuche proportion, 95% CI 3.1% to 4.0%, p = 1.0×10-59), suggesting a mediating effect of gallstones in the relationship between Mapuche ancestry and GBC. In contrast, the proportion of Mapuche ancestry showed a negative causal effect on BMI (IVW estimate -0.006 kg/m2 per 1% increase in Mapuche proportion, 95% CI -0.009 to -0.003, p = 4.4×10-5). Conclusions The results presented here may have significant implications for GBC prevention and are important for future admixture mapping studies. Given that the association between Mapuche ancestry and GBC risk previously noted in observational studies appears to be causal, primary and secondary prevention strategies that take into account the individual proportion of Mapuche ancestry could be particularly efficient. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was supported by the European Union’s Horizon 2020 research and innovation program (grant 825741, JLB, ) and the Deutsche Forschungsgemeinschaft (DFG grant LO 1928/11-1, project number 424112940, JLB, ). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Not Applicable The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study protocol conformed to the ethical guidelines of the 1975 Declaration of Helsinki and was approved by the ethics committees of Servicio de Salud Metropolitano Oriente, Santiago de Chile (#06.10.2015, #08.03.2016 and #12.11.2019), Servicio de Salud Metropolitano Sur Oriente, Santiago de Chile (#15.10.2015 and #05.04.2018), Servicio de Salud Metropolitano Central, Santiago de Chile (#1188-2015), Servicio de Salud Coquimbo, Coquimbo, Chile (#01.04.2016), Servicio de Salud Maule, Talca, Chile (#05.11.2015), Universidad Cat#x00F3;lica del Maule, Talca, Chile (#102-2020), Servicio de Salud Concepción, Concepción, Chile (ID: 16-11-97 and ID:19-12-111), Servicio de Salud Araucanía Sur, Temuco, Chile (#10.02.2020), Servicio de Salud Valdivia, Valdivia, Chile (ID:438), Centro de Bioética, Universidad del Desarrollo, Cl#x00ED;nica Alemana de Santiago, Santiago de Chile (#2018-97, ID 678) and Unidad de Investigación Hospital San Juan de Dios, Santiago de Chile (#6182), the Medical Faculties of Universidad de Chile (approval #123-2012 and #11.10.2012) and Pontificia Universidad Cat#x00F3;lica de Chile (#11-159), and Universidad de Tarapacá and University College London as described in ([Ruiz-Linares et al., 2014][1]). All participants provided written informed consent before enrolment. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Not Applicable I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Not Applicable I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Not Applicable The source code to reproduce all the results described is provided as supplementary material, and the necessary input files are available at [www.biometrie.uni-heidelberg.de/StatisticalGenetics/Software\_and\_Data][2]. [www.biometrie.uni-heidelberg.de/StatisticalGenetics/Software\_and\_Data][2] [1]: #ref-27 [2]: http://www.biometrie.uni-heidelberg.de/StatisticalGenetics/Software_and_Data

Long noncoding RNAs (lncRNAs) play key roles in cell processes and are good candidates for cancer risk prediction. Few studies have investigated the association between individual genotypes and lncRNA expression. Here we integrate three separate datasets with information on lncRNA expression only, both lncRNA expression and genotype, and genotype information only to identify circulating lncRNAs associated with the risk of gallbladder cancer (GBC) using robust linear and logistic regression techniques. In the first dataset, we preselect lncRNAs based on expression changes along the sequence “gallstones → dysplasia → GBC”. In the second dataset, we validate associations between genetic variants and serum expression levels of the preselected lncRNAs (cis-lncRNA-eQTLs) and build lncRNA expression prediction models. In the third dataset, we predict serum lncRNA expression based on individual genotypes and assess the association between genotype-based expression and GBC risk. AC084082.3 and LINC00662 showed increasing expression levels (p-value = 0.009), while C22orf34 expression decreased in the sequence from gallstones to GBC (p-value = 0.04). We identified and validated two cis-LINC00662-eQTLs (r2 = 0.26) and three cis-C22orf34-eQTLs (r2 = 0.24). Only LINC00662 showed a genotyped-based serum expression associated with GBC risk (OR = 1.25 per log2 expression unit, 95% CI 1.04–1.52, p-value = 0.02). Our results suggest that preselection of lncRNAs based on tissue samples and exploitation of cis-lncRNA-eQTLs may facilitate the identification of circulating noncoding RNAs linked to cancer risk.

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.

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.