High frequency of pathogenic germline variants in genes associated with homologous recombination repair in patients with advanced solid cancers
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE131027 | GEO | 2019/05/11
REPOSITORIES: GEO
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Project description:Objectives. Ovarian cancer (OC) is the eighth most common cancer and the eighth most common cause of cancer-related death in women. Identification of pathogenic variants in OC tissues is important to predict treatment response. This study aim to evaluate the mutational profile of a patient cohort, negative for BRCA1/2 germinal mutations and Mismatch Repair (MMR) defects, using next generation sequencing approach on DNA from formalin-fixed paraffin-embedded (FFPE) samples. We used a custom NGS panel, targeting 34 cancer related-genes, and analyzed NGS data to identify somatic and germline mutations in Italian patients affected by primary epithelia ovarian cancer.
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Project description:Delineating functionally normal variants from functionally abnormal variants in tumor suppressor proteins is critical for cancer surveillance, prognosis, and treatment options. BRCA1 is a protein that has many variants of uncertain significance which are not yet classified as functionally normal or abnormal. In vitro functional assays can be used to identify the functional impact of a variant when the variant has not yet been categorized through clinical observation. Here we employ a homology-directed repair (HDR) reporter assay to evaluate over 300 missense and nonsense BRCA1 variants between amino acid residues 1280 and 1576, which encompasses the coiled-coil and serine cluster domains. Functionally abnormal variants tended to cluster in residues known to interact with PALB2, which is critical for homology-directed repair. Multiplexed results were confirmed by singleton assay and by ClinVar database variant interpretations. Comparison of multiplexed results to designated benign or likely benign or pathogenic or likely pathogenic variants in the ClinVar database yielded 100% specificity and 100% sensitivity of the multiplexed assay. Clinicians can reference the results of this functional assay for help in guiding cancer treatment and surveillance options. These results are the first to evaluate this domain of BRCA1 using a multiplexed approach and indicate the importance of this domain in the DNA repair process.
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Project description:This is a pathogenic mutation profile of colorectal patients specifically in 5 genes, i.e. APC, TP53, PIK3CA, KRAS, and MLH1. Single nucleotide variants identified were synchronized with patients’ characteristics.
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Project description:Mutational inactivation of TP53 is a common event in cancer. Germline mutations in TP53 that inactivate this protein also occur in Li Fraumeni syndrome, which predisposes to early-onset cancer. In addition, there are dozens of other germline variants in TP53 that do not completely inactivate the function of this protein. In many cases studies have shown strong support for an impact of these lesser-functioning hypomorphs with increased cancer risk in humans and mouse models; however, the majority of these hypomorphs have yet to be categorized as pathogenic in clinical genetics databases. There is thus need for a functional assay to distinguish lesser-functioning hypomorphic p53 variants from wild type p53, or benign, fully-functional, variants. We report the surprising finding that two different African-centric genetic hypomorphs of p53, which occur in distinct functional domains of the protein, share common activities. We show that the Pro47Ser variant in the transactivation domain and the Tyr107His variant in the DNA binding domain both share increased propensity to misfold into a conformation specific for mutant p53. Moreover, cells and tissues with these variants show increased NF-B activity. We have identified a common gene signature from unstressed lymphocyte cell lines that is shared between these two, and other, genetic missense hypomorphs of TP53. We show that this gene signature successfully distinguishes wild type p53 and a benign p53 variant from lesser-functioning hypomorphic variants. These findings should allow us to better understand how hypomorphic variants contribute to cancer risk, and to better inform cancer risk in hypomorph carriers.
2023-03-01 | GSE209837 | GEO
Project description:Background: Causative genes are mostly unknown for the mismatch repair-proficient category of familial colorectal cancers designated as FCCTX. Recent evidence suggests shared susceptibility factors between colorectal and hematological malignancies. Study design: We investigated 28 FCCTX families by exome sequencing, supplemented with whole genome sequencing, RNA-sequencing, and tumor studies to identify the predisposing genes. Guided by the findings, germline and somatic exomes of ~400 patients with acute leukemia, myelodysplastic syndrome, and myeloma were subsequently examined. Results: A family with hematological and solid malignancies revealed a truncating variant in the DEAH-box RNA helicase gene DHX40 co-segregating with disease in seven family members. Neoplastic tissues revealed no apparent “second hit”, implying a haploinsufficiency model of tumorigenesis. DHX40 siRNA-treated cell lines exhibited a 13% increase in aberrantly spliced transcripts vs. GAPDH-siRNA or non-target siRNA-treated cells. Two additional families showed truncating germline variants in the TDRD9 and TDRD5 genes encoding Tudor domain-containing RNA-binding proteins. In the hospital-based hematological series, 18% of germline and 28% of somatic exomes revealed possibly pathogenic DEAD/H box gene variants, including somatic variants of DHX40 in four. Conclusions: This study identifies DHX40, TDRD9, and TDRD5 as novel candidate genes for FCCTX predisposition. In the family segregating the truncating DHX40 variant, two carriers had hematological neoplasia, suggesting possible analogy to DDX41, a DEAD-box RNA helicase gene previously linked to myeloid malignancies. Our findings emphasize aberrant RNA metabolism behind FCCTX and hematological neoplasia.
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Project description:Background: In ~50% of Lynch syndrome (LS)-suspected patients (also called Lynch-like syndrome, LLS), the causal mechanism for cancer predisposition remains unknown. Our aim was to elucidate the constitutional basis of mismatch repair (MMR) deficiency in LLS patients throughout a comprehensive genetic and epigenetic analysis. Methods: One hundred and fifteen LLS patients harboring MMR deficient tumors and no pathogenic germline MMR gene mutations were included in this study. Mutational analysis of 26 colorectal cancer associated genes was performed by using a customized multigene panel and massively parallel sequencing. Pathogenicity of MMR variants was assessed by mRNA analysis and multifactorial likelihood calculations. Genome-wide methylome analysis was perfomed by using the Infinium HumanMethylation450K BeadChip. Results: The multigene panel analysis revealed the presence of two MMR gene truncating mutations not found in previous analysis. Of a total of 15 MMR variants of unknown significance identified, five - present in 6 unrelated individuals- were reclassified as pathogenic. In addition, 13 predicted deleterious variants in other CRC-predisposing genes (MSH3, MUTYH, POLD1, APC, EPCAM, BUB1, FAN1, EXO1 or PSM1) were found in 12 probands. Methylome analysis detected one constitutional MLH1 epimutation in an individual diagnosed with CRC at age 42, but no additional differentially methylated regions were identified in LLS compared to LS patients or healthy individuals. Conclusions: In conclusion, the use of an ad-hoc designed gene panel combined with pathogenicity assessment of variants allows the identification of deleterious MMR mutations as well as new LLS candidate genes. Moreover, constitutional epimutations in non-LS-associated genes are not responsible for the MMR-deficient phenotype observed in LLS patients.
2019-03-09 | GSE128064 | GEO
Project description:Background: In ~50% of Lynch syndrome (LS)-suspected patients (also called Lynch-like syndrome, LLS), the causal mechanism for cancer predisposition remains unknown. Our aim was to elucidate the constitutional basis of mismatch repair (MMR) deficiency in LLS patients throughout a comprehensive genetic and epigenetic analysis. Methods: One hundred and fifteen LLS patients harboring MMR deficient tumors and no pathogenic germline MMR gene mutations were included in this study. Mutational analysis of 26 colorectal cancer associated genes was performed by using a customized multigene panel and massively parallel sequencing. Pathogenicity of MMR variants was assessed by mRNA analysis and multifactorial likelihood calculations. Genome-wide methylome analysis was perfomed by using the Infinium HumanMethylation450K BeadChip. Results: The multigene panel analysis revealed the presence of two MMR gene truncating mutations not found in previous analysis. Of a total of 15 MMR variants of unknown significance identified, five - present in 6 unrelated individuals- were reclassified as pathogenic. In addition, 13 predicted deleterious variants in other CRC-predisposing genes (MSH3, MUTYH, POLD1, APC, EPCAM, BUB1, FAN1, EXO1 or PSM1) were found in 12 probands. Methylome analysis detected one constitutional MLH1 epimutation in an individual diagnosed with CRC at age 42, but no additional differentially methylated regions were identified in LLS compared to LS patients or healthy individuals. Conclusions: In conclusion, the use of an ad-hoc designed gene panel combined with pathogenicity assessment of variants allows the identification of deleterious MMR mutations as well as new LLS candidate genes. Moreover, constitutional epimutations in non-LS-associated genes are not responsible for the MMR-deficient phenotype observed in LLS patients.
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Project description:Inherited non-coding genetic variants confer significant disease susceptibility in many cancers. However, the molecular processes by which germline variants contribute to somatic lesions are poorly understood. We performed targeted sequencing in 5,008 patients and identified a key regulatory germline variant in GATA3 strongly associated with Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL). By creating an isogenic cellular model with a CRISPR-Cas9 system, we showed that this variant activated a strong enhancer that significantly upregulated GATA3 transcription, which in turn reshaped the global chromatin accessibility and 3D genome organization. Remarkably, this genotype switch induced a chromatin loop between the CRLF2 oncogene and a distal enhancer, similar to the somatically acquired super-enhancer hijacking event in patients. GATA3 genotype-related alterations in transcriptional control and 3D chromatin organization were further validated in Ph-like ALL patients. Finally, we showed that GATA3 directly regulates CRLF2 and potentiates the oncogenic effects of JAK-STAT signaling in leukemogenesis. Altogether, our results provide evidence for a novel mechanism by which a germline non-coding variant contributes to oncogene activation epigenetic regulation and 3D genome reprogramming.
2021-09-13 | GSE145997 | GEO
Project description:Lynch syndrome (LS) predisposes to cancer in adulthood and is caused by heterozygous germline variants in a mismatch repair (MMR) gene. Recent studies show an increased prevalence of LS among children with cancer, suggesting a causal relationship. For LS-spectrum (LSS) cancers, including high-grade gliomas and colorectal cancer, causality has been supported by typical MMR-related tumor characteristics, but for non-LSS cancers, causality is unclear. This dataset contains 5 patients with Lynch Syndrome from the INFORM registry.
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