Determining the effectiveness of High Resolution Melting analysis for SNP genotyping and mutation scanning at the TP53 locus

<p>Abstract</p> <p>Background</p> <p>Together single nucleotide substitutions and small insertion/deletion variants are the most common form of sequence variation in the human gene pool.</p> <p>High-resolution SNP profile and/or haplotype analyses enable the identification of modest-risk susceptibility genes to common diseases, genes that may modulate responses to pharmaceutical agents, and SNPs that can affect either their expression or function. In addition, sensitive techniques for germline or somatic mutation detection are important tools for characterizing sequence variations in genes responsible for tumor predisposition. Cost-effective methods are highly desirable. Many of the recently developed high-throughput technologies are geared toward industrial scale genetic studies and arguably do not provide useful solutions for small laboratory investigator-initiated projects. Recently, the use of new fluorescent dyes allowed the high-resolution analysis of DNA melting curves (HRM).</p> <p>Results</p> <p>Here, we compared the capacity of HRM, applicable to both genotyping and mutation scanning, to detect genetic variations in the tumor suppressor gene <it>TP53 </it>with that of mutation screening by full resequencing. We also assessed the performance of a variety of available HRM-based genotyping assays by genotyping 30 <it>TP53 </it>SNPs. We describe a series of solutions to handle the difficulties that may arise in large-scale application of HRM to mutation screening and genotyping at the <it>TP53 </it>locus. In particular, we developed specific HRM assays that render possible genotyping of 2 or more, sometimes closely spaced, polymorphisms within the same amplicon. We also show that simultaneous genotyping of 2 SNPs from 2 different amplicons using a multiplex PCR reaction is feasible; the data can be analyzed in a single HRM run, potentially improving the efficiency of HRM genotyping workflows.</p> <p>Conclusion</p> <p>The HRM technique showed high sensitivity and specificity (1.0, and 0.8, respectively, for amplicons of <400 bp) for mutation screening and provided useful genotyping assays as assessed by comparing the results with those obtained with Sanger sequencing. Thus, HRM is particularly suitable for either performing mutation scanning of a large number of samples, even in the situation where the amplicon(s) of interest harbor a common variant that may disturb the analysis, or in a context where gathering common SNP genotypes is of interest.</p

Hepatitis B virus preS2Δ38-55 variants: A newly identified risk factor for hepatocellular carcinoma.

BACKGROUND & AIMS: Although HBV is a major cause of death in Africa, its genetic variability has been poorly documented. This study aimed to address whether HBV genotype and surface gene variants are associated with HBV-related liver disease in The Gambia. METHODS: We conducted a case-control study nested in the Prevention of Liver Fibrosis and Cancer in Africa programme. Consecutive treatment-naive patients with chronic HBV infection and detectable viral load were recruited: 211 controls with no significant liver disease and 91 cases (56 cirrhosis and 35 HCC cases). HBV genotypes and surface gene variants were determined by Sanger sequencing or next-generation sequencing (NGS) in serum DNA. Aflatoxin B1 (AFB1)-specific codon 249 TP53 mutation was determined by NGS in circulating cell-free plasma DNA. RESULTS: In phylogenetic analysis, 85% of individuals carried HBV genotype E, 14% genotype A, and 1% A/E recombinant viruses. Surface gene variants were more frequently observed in cases (43% and 57% in cirrhosis and HCC cases, respectively) than controls (25%; p 2,000 IU/ml (OR 22.7 [8.0-64.9]), HBsAg levels <10,000 IU/ml (OR 19.0 [5.5-65.3]), and AFB1 exposure (OR 29.3 [3.7-230.4]) on HCC risk. CONCLUSIONS: This study identified a hotspot for HBV preS2 deletions as a strong independent factor for HCC in The Gambia, with HBV genotypes and AFB1 exposure contributing to the high liver cancer risk. LAY SUMMARY: Although HBV-related liver disease is highly prevalent in sub-Saharan Africa, the associated virological characteristics are poorly studied. Using clinical data from African patients chronically infected with HBV, an assessment of the virological variability (genotypes and mutations) and exposure to AFB1, a toxin often contaminating food, was carried out. Our results show that HBV genotypes, the presence of a highly prevalent mutant form of HBV, and AFB1 exposure contribute to the high liver cancer risk in this population

Genetic Analysis of Lung Cancer and the Germline Impact on Somatic Mutation Burden

International audienceBackground Germline genetic variation contributes to lung cancer (LC) susceptibility. Previous genome-wide association studies (GWAS) have implicated susceptibility loci involved in smoking behaviors and DNA repair genes, but further work is required to identify susceptibility variants. Methods To identify LC susceptibility loci, a family history-based genome-wide association by proxy (GWAx) of LC (48 843 European proxy LC patients, 195 387 controls) was combined with a previous LC GWAS (29 266 patients, 56 450 controls) by meta-analysis. Colocalization was used to explore candidate genes and overlap with existing traits at discovered susceptibility loci. Polygenic risk scores (PRS) were tested within an independent validation cohort (1 666 LC patients vs 6 664 controls) using variants selected from the LC susceptibility loci and a novel selection approach using published GWAS summary statistics. Finally, the effects of the LC PRS on somatic mutational burden were explored in patients whose tumor resections have been profiled by exome (n = 685) and genome sequencing (n = 61). Statistical tests were 2-sided. Results The GWAx–GWAS meta-analysis identified 8 novel LC loci. Colocalization implicated DNA repair genes (CHEK1), metabolic genes (CYP1A1), and smoking propensity genes (CHRNA4 and CHRNB2). PRS analysis demonstrated that these variants, as well as subgenome-wide significant variants related to expression quantitative trait loci and/or smoking propensity, assisted in LC genetic risk prediction (odds ratio = 1.37, 95% confidence interval = 1.29 to 1.45; P &lt; .001). Patients with higher genetic PRS loads of smoking-related variants tended to have higher mutation burdens in their lung tumors. Conclusions This study has expanded the number of LC susceptibility loci and provided insights into the molecular mechanisms by which these susceptibility variants contribute to LC development

No evidence that protein truncating variants in BRIP1 are associated with breast cancer risk: implications for gene panel testing.

BACKGROUND: BRCA1 interacting protein C-terminal helicase 1 (BRIP1) is one of the Fanconi Anaemia Complementation (FANC) group family of DNA repair proteins. Biallelic mutations in BRIP1 are responsible for FANC group J, and previous studies have also suggested that rare protein truncating variants in BRIP1 are associated with an increased risk of breast cancer. These studies have led to inclusion of BRIP1 on targeted sequencing panels for breast cancer risk prediction. METHODS: We evaluated a truncating variant, p.Arg798Ter (rs137852986), and 10 missense variants of BRIP1, in 48 144 cases and 43 607 controls of European origin, drawn from 41 studies participating in the Breast Cancer Association Consortium (BCAC). Additionally, we sequenced the coding regions of BRIP1 in 13 213 cases and 5242 controls from the UK, 1313 cases and 1123 controls from three population-based studies as part of the Breast Cancer Family Registry, and 1853 familial cases and 2001 controls from Australia. RESULTS: The rare truncating allele of rs137852986 was observed in 23 cases and 18 controls in Europeans in BCAC (OR 1.09, 95% CI 0.58 to 2.03, p=0.79). Truncating variants were found in the sequencing studies in 34 cases (0.21%) and 19 controls (0.23%) (combined OR 0.90, 95% CI 0.48 to 1.70, p=0.75). CONCLUSIONS: These results suggest that truncating variants in BRIP1, and in particular p.Arg798Ter, are not associated with a substantial increase in breast cancer risk. Such observations have important implications for the reporting of results from breast cancer screening panels.The COGS project is funded through a European Commission's Seventh Framework Programme grant (agreement number 223175 - HEALTH-F2-2009-223175). BCAC is funded by Cancer Research UK [C1287/A10118, C1287/A12014] and by the European Community´s Seventh Framework Programme under grant agreement number 223175 (grant number HEALTH-F2-2009-223175) (COGS). Funding for the iCOGS infrastructure came from: the European Community's Seventh Framework Programme under grant agreement n° 223175 (HEALTH-F2-2009-223175) (COGS), Cancer Research UK (C1287/A10118, C1287/A 10710, C12292/A11174, C1281/A12014, C5047/A8384, C5047/A15007, C5047/A10692, C8197/A16565), the National Institutes of Health (CA128978) and Post-Cancer GWAS initiative (1U19 CA148537, 1U19 16 CA148065 and 1U19 CA148112 - the GAME-ON initiative), the Department of Defense (W81XWH-10-1- 0341), the Canadian Institutes of Health Research (CIHR) for the CIHR Team in Familial Risks of Breast Cancer, Komen Foundation for the Cure, the Breast Cancer Research Foundation, and the Ovarian Cancer Research Fund. This study made use of data generated by the Wellcome Trust Case Control consortium. Funding for the project was provided by the Wellcome Trust under award 076113. The results published here are in part based upon data generated by The Cancer Genome Atlas Project established by the National Cancer Institute and National Human Genome Research Institute.This is the author accepted manuscript. The final version is available from BMJ Group at http://dx.doi.org/10.1136/jmedgenet-2015-103529

Integrative and comparative genomic analyses identify clinically relevant pulmonary carcinoid groups and unveil the supra-carcinoids

International audienceThe worldwide incidence of pulmonary carcinoids is increasing, but little is known about their molecular characteristics. Through machine learning and multi-omics factor analysis, we compare and contrast the genomic profiles of 116 pulmonary carcinoids (including 35 atypical), 75 large-cell neuroendocrine carcinomas (LCNEC), and 66 small-cell lung cancers. Here we report that the integrative analyses on 257 lung neuroendocrine neoplasms stratify atypical carcinoids into two prognostic groups with a 10-year overall survival of 88% and 27%, respectively. We identify therapeutically relevant molecular groups of pulmonary car-cinoids, suggesting DLL3 and the immune system as candidate therapeutic targets; we confirm the value of OTP expression levels for the prognosis and diagnosis of these diseases, and we unveil the group of supra-carcinoids. This group comprises samples with carcinoid-like morphology yet the molecular and clinical features of the deadly LCNEC, further supporting the previously proposed molecular link between the low-and high-grade lung neuroendocrine neoplasms

Développement d’un système informatique intégré pour la gestion des données de laboratoire et des étapes de séquençage de nouvelle génération au sein d’une plateforme de recherche en génomique du cancer

The aim of my thesis work was to develop bioinformatics tools to improve the traditional scientific information management within a large research centre and especially within a genomics platform. Three tools have been developed: an electronic laboratory notebook, a laboratory information management system for genomics applications including next generation sequencing, as well as a sample management system for large biobanks. This work has been conducted in close collaboration with biologists, epidemiologists and IT specialists. It has also included the setup of interactions between the different tools to make an integrated IT system. The three tools have been rapidly adopted by all the scientists of the research centre and are now daily used for the tracking of all the laboratory’s activities but also more globally for the research centre’s other scientific activities. These tools are transposable in other research institutesL'objectif de mon travail de thèse était de développer des outils bio informatiques permettant d'améliorer la traditionnelle gestion de l'information scientifique au sein d'un grand centre de recherche et en particulier au sein d'une plateforme de génomique. Trois outils ont été développés: un cahier de laboratoire électronique, un système de gestion de l'information de laboratoire pour des applications de génomique dont le séquençage de nouvelle génération, ainsi qu'un système de gestion des échantillons pour de grandes bio-banques. Ce travail a été réalisé en étroite collaboration avec des biologistes, épidémiologistes et informaticiens. Il a également inclus la mise en place d'interactions entre les différents outils pour former un système informatique intégré. Les trois outils ont été rapidement adoptés par l'ensemble des scientifiques du centre de recherche et sont désormais utilisés au quotidien pour le suivi de toutes les activités de laboratoire mais aussi plus globalement pour les autres activités scientifiques du centre de recherche. Ces outils sont transposables dans d'autres instituts de recherch

Detection of BRCA1/2 mutations in breast cancer patients from Thailand and Pakistan.

International audienc

Genetic susceptibility factors in familial nasopharyngeal carcinoma

Nasopharyngeal carcinoma is common in Southern China, Hong Kong, Taiwan and Southeast Asian countries. The current study was performed on an exceptionally large multiplex NPC family from Sarawak, Malaysia (denoted as JAQBAB family). We aimed to explore the segregation of deleterious mutation(s) or NPC risk- associated allele within the genomic segment shared identical by descent (IBD) between the affected individuals. Genome-wide SNP-array covering all somatic chromosomes were performed on 11 of the NPC patients and their first-degree family members. The kinship was assessed and pairwise IBD estimation between target individuals were performed. Haplotype phasing was also performed on certain region of interests. Whole-exome sequencing was performed to identify deleterious mutations. The highest IBD score was detected within chromosome 10. Analysis of the exome sequencing data, however, did not find any deleterious mutation within this region that was shared between individuals in the JAQBAB family. Highest IBD score at chromosome 6 was found within the major histocompatibility complex (MHC) region, supporting strong HLA-EBV-NPC association that has been reported in an earlier study. HLA deep sequence-based typing (SBT) and gene sequencing on the 11 NPC patient samples revealed that the segregation of HLA-A*27:07 allele was consistent with the haplotype phasing pattern. Our results suggest that HLA-A*24:07 may harbour the risk allele for NPC among the subjects. However, further analysis is required before any definitive conclusion can be made. Further studies on the HLA-A*24:07 sequence may reveal more specific variation within this gene that can be associated with NPC risk in this family. In addition, further studies on HLA-A and risk of NPC other Southeast-Asian populations may shed more understanding about the association between HLA-A*24:07 and sporadic NPC in this region of the world

Beta HPV38 oncoproteins act with a hit-and-run mechanism in ultraviolet radiation-induced skin carcinogenesis in mice.

Cutaneous beta human papillomavirus (HPV) types are suspected to be involved, together with ultraviolet (UV) radiation, in the development of non-melanoma skin cancer (NMSC). Studies in in vitro and in vivo experimental models have highlighted the transforming properties of beta HPV E6 and E7 oncoproteins. However, epidemiological findings indicate that beta HPV types may be required only at an initial stage of carcinogenesis, and may become dispensable after full establishment of NMSC. Here, we further investigate the potential role of beta HPVs in NMSC using a Cre-loxP-based transgenic (Tg) mouse model that expresses beta HPV38 E6 and E7 oncogenes in the basal layer of the skin epidermis and is highly susceptible to UV-induced carcinogenesis. Using whole-exome sequencing, we show that, in contrast to WT animals, when exposed to chronic UV irradiation K14 HPV38 E6/E7 Tg mice accumulate a large number of UV-induced DNA mutations, which increase proportionally with the severity of the skin lesions. The mutation pattern detected in the Tg skin lesions closely resembles that detected in human NMSC, with the highest mutation rate in p53 and Notch genes. Using the Cre-lox recombination system, we observed that deletion of the viral oncogenes after development of UV-induced skin lesions did not affect the tumour growth. Together, these findings support the concept that beta HPV types act only at an initial stage of carcinogenesis, by potentiating the deleterious effects of UV radiation