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PubMed2026

Frequency and clinical features of germline pathogenic variants in sarcoma: a case-control study.

BACKGROUND: Germline multigene panel testing is not yet integrated into standard care for patients with sarcoma. This study aimed to assess the frequency and distribution of germline pathogenic variants in patients with sarcoma compared with cancer-free controls and identify differences between patients with and without germline pathogenic variants. METHODS: This retrospective cohort included 488 sarcoma patients and 2440 cancer-free controls matched 1:5 by age, sex, and ethnicity. Multigene panel testing was performed between 2016 and 2024 at a single germline testing laboratory. The frequency of germline pathogenic variants in selected genes was compared using Fisher exact test with odds ratios (ORs) and 95% confidence intervals. Additionally, within the case-only cohort, clinical characteristics were evaluated to assess associations with the presence of germline pathogenic variants in any gene. RESULTS: Among 488 patients with sarcoma, 67.8% (n = 331) were female, with a median age at sarcoma diagnosis of 47 years (range = 0.5-87.5 years). Cases had a higher frequency of germline pathogenic variants compared with controls (26.2% vs 10.5%; OR = 3.05, P < .001). We observed a higher frequency of germline pathogenic variants in TP53, BRCA2, CHEK2, NF1, SDHA, BRIP1, POT1, RB1, and CDH1 among patients with sarcoma compared with controls. Age at sarcoma diagnosis did not differ between groups. CONCLUSIONS: This study confirms the high detection rate of germline pathogenic variants in patients with sarcoma and describes several associated genes. These findings indicate that age at sarcoma diagnosis may not reliably predict germline pathogenic variants. Expanding germline testing for patients with sarcoma would enhance personalized treatment strategies and familial risk assessment.

Humans↗

PubMed2026

Distinct mutational landscapes for germline and somatic cancer variants in forty tumor suppressor genes.

Germline and somatic cancer variants in tumor suppressor genes (TSGs) share loss-of-function mechanisms, but studies of a few genes (DICER1 and CEBPA) have demonstrated differences in variant consequence and location. To systematically assess whether TSGs display distinct mutational patterns, we leveraged large public genetic databases and compared 32,941 high-quality pathogenic/likely pathogenic (P/LP) germline variants in ClinVar, with 12,907 oncogenic/likely oncogenic (O/LO) somatic tumor variants from cBioPortal across 40 TSGs. Only 3,863 (9.2%) variants were shared. Eighteen TSGs showed significantly different distributions of variant occurrences by molecular consequence, replicated with non-overlapping somatic data from the COSMIC database (chi-squared tests, false discovery rate = 5%). DICER1, TP53, and SMAD4 displayed excess somatic missense events, while nine TSGs (e.g., RB1 and APC) contained excess somatic stop-gain events throughout the coding sequence. Analysis by tumor type revealed excess stop-gain events in tissues exposed to environmental mutagens with corresponding mutation signatures. For several TSGs (WT1), germline variants predispose to tumors (Wilms' tumor) distinct from the majority source of somatic data (myeloid leukemia). Germline and somatic events are also distributed unevenly across cDNA locations, with 103 regions of preferential clustering in 39 TSGs (78 somatic and 25 germline). Twenty somatic clusters contained recurring frameshifts in homopolymer runs, many in tumors with microsatellite instability. Germline clusters contain more germline-exclusive variants, some driving non-cancer phenotypes reflecting genetic pleiotropy. Altogether, germline and somatic variants of TSGs represent unique sets with substantially different patterns shaped by selection pressures from gene-specific and somatic mutational mechanisms. Characterizing these distinctions enables more accurate clinical interpretation of TSG variants.

Humans↗

PubMed2026

Bayesian Integration of Tumor Mutational Signatures and Somatic Features Refines Pathogenicity Assessment of Germline Mismatch Repair Variants.

Variants of uncertain significance (VUS) in mismatch repair (MMR) genes represent a persistent bottleneck in germline interpretation for Lynch syndrome, creating a critical opportunity to leverage tumor biology to refine pathogenicity assessment. Although tumor features such as microsatellite instability (MSI) and immunohistochemistry (IHC) are routinely evaluated, they are typically interpreted separately from germline classification, and their quantitative contribution within ACMG/AMP frameworks remains poorly defined. We therefore analyzed paired germline and tumor sequencing data from 1110 tumors across 1073 patients with colorectal or endometrial cancer to determine whether mismatch repair-deficient (MMR-d) mutational signatures can be quantitatively integrated into Bayesian germline variant interpretation. Using COSMIC single-base substitution signatures, tumors were classified as MMR-d or MMR proficient, and an empirically derived likelihood ratio (LR) quantified the association between MMR-d signatures and pathogenic germline MMR variants. The presence of an MMR-d signature increased the likelihood of an underlying pathogenic germline MMR variant approximately eightfold (LR ≈ 8; log10 LR ≈ 0.90), whereas its absence provided moderate-to-strong benign evidence (LR ≈ 0.156; log10 LR ≈ -0.81). Applying this integrative framework to 45 germline MMR VUS, joint modeling of tumor mutational signatures with additional somatic and variant-level evidence resulted in clinically significant reclassification of 38 (84.4%) variants, including three reclassified as pathogenic or likely pathogenic and 35 as likely benign. A total of 16 downgraded variants were independently downgraded by Invitae. These findings demonstrate that tumor mutational signatures can be formally incorporated into Bayesian germline interpretation, transforming tumor data into quantitative pathogenicity evidence and offering a principled strategy to reduce VUS burden in hereditary cancer genetics.

Humans↗

PubMed2026

Novel Co-Occurrence of Germline EGFR p.V843I and Somatic EGFR Exon 19 Deletion in NSCLC: Insights into Reduced Sensitivity to EGFR-TKIs.

Germline EGFR pathogenic variants (PVs) are rare and define a distinct hereditary subset of NSCLC with unique clinical characteristics. Germline EGFR p.T790M is the most frequent and best characterized, with reported sensitivity to first- and second-generation EGFR-TKIs. Yet, the response of germline EGFR variants, especially the rarer ones such as p.V843I, to osimertinib remains poorly characterized. Given the very low frequency of germline non-p.T790M variants, their clinical relevance can only be investigated via case reports. Herein, we report what is, to the best of our knowledge, the first case of advanced lung adenocarcinoma harboring a germline EGFR p.V843I variant coexisting in cis with the unusual somatic EGFR exon 19 C-helix deletion, p.S752_I759del. Additionally, a somatic TP53 variant was detected. Treatment with afatinib induced a partial response lasting only six months, as rapid disease progression occurred without identifiable acquired resistance mechanisms. Subsequently, no objective response to osimertinib or afatinib rechallenge was observed. Acquired EGFR and MET amplification were detected in corresponding rebiopsies. Overall survival was 29 months. Our findings suggest that, despite the presence of the previously reported EGFR-TKI-sensitive, EGFR p.S752_I759del, the co-occurrence of germline p.V843I may have contributed to reduced sensitivity to afatinib and osimertinib. This case expands the molecular spectrum of hereditary EGFR-mutated NSCLC and, together with our narrative review of the literature, supports an emerging model in which germline EGFR PVs may act both as tumor-predisposing events and as potential mechanisms of early resistance to EGFR-TKIs.

Humans↗

PubMed2025

Comparative Analysis of Somatic and Germline Polymerase Proofreading Deficiencies in Cancer: Molecular and Clinical Implications.

Polymerases ε and δ maintain genome integrity through exonuclease proofreading. Germline and somatic pathogenic variants (PVs) in the exonuclease domain (ED) of POLE and POLD1 impair proofreading, causing hypermutated tumors. Despite shared mutational features that make these tumors highly immunogenic, molecular and clinical distinctions between POLE and POLD1 mutations and between somatic and germline variants remain incompletely understood. We compared the molecular and clinical characteristics of POLE and POLD1 ED PVs (n = 31), assessing their location, pathogenicity, clinical phenotypes, mismatch repair (MMR) status, tumor mutational burden, and signatures. We analyzed 360 proofreading-deficient tumors (source: The Cancer Genome Atlas [TCGA] and Catalogue Of Somatic Mutations In Cancer [COSMIC]) and 70 families (249 individuals) with polymerase proofreading-associated polyposis. All germline and somatic PVs had high AlphaMissense scores (0.87-1) and clustered within or near Exo motifs. Recurrent, nonfounder germline PVs, POLE L424V and POLD1 S478N, showed low/modest REVEL scores. Somatic variants occurred mainly in endometrial cancers (75% of proofreading-deficient TCGA cancers), whereas colorectal cancer predominated in polymerase proofreading-associated polyposis (56% of carriers). Cancer risks and tumor spectra differed between POLE and POLD1 PV carriers. Aggressive hereditary phenotypes were linked to either specific POLE PVs (eg, S297F, V411L, P436R, M444K, A456P, and S461T) or the co-occurrence of germline ED PVs with germline MMR gene PVs. Distinct hypermutator profiles were confirmed for polymerase ε and polymerase δ proofreading deficiencies via unique mutational signatures (Polymerase ε: SBS10a/b, SBS28; Polymerase δ: SBS10c/d). Tumors with combined proofreading and MMR deficiencies had significantly higher tumor mutational burden and a shift in the associated mutational spectra. Unlike POLE, POLD1 ED PVs exhibited haplosufficiency, typically requiring a somatic second hit (eg, loss of heterozygosity) or MMR deficiency to drive hypermutation. In conclusion, differences between POLE and POLD1 and between somatic and germline mutations influence clinical presentation, mutagenic potential, and reliance on cooperating defects in tumorigenesis. These insights advance the understanding of proofreading-deficient cancers, with implications for diagnostics, genetic counseling, and precision oncology.

Humans↗

PubMed2026

Precision medicine and parental experience: a longitudinal study of psychosocial responses to germline genomic results in pediatric oncology.

INTRODUCTION: Precision medicine has become central to pediatric oncology, with germline genomic sequencing commonly integrated into routine care. Families must interpret complex genomic findings during emotionally vulnerable periods, generating mixed reactions ranging from clarity and relief to anxiety and uncertainty. Palliative care clinicians, genetic counselors, psychologists, social workers, and oncology providers may each contribute to supporting families as they interpret and integrate these findings over the course of a child's cancer care and beyond. Little is known about the trajectory of parental emotional and cognitive responses after receiving germline sequencing results, limiting clinicians' ability to anticipate support needs across the cancer care continuum. This study quantitatively examines parental emotional and cognitive responses across time following disclosure of germline sequencing results in a pediatric oncology setting. METHODS: Parents (n = 218) self-reported sequencing-related distress, positive feelings, intrusive thoughts, certainty, and self-efficacy using validated measures at two longitudinal follow-up points after disclosure of their child's germline test results. Outcomes were compared across germline test result types (pathogenic/likely pathogenic [P/LP], n = 31 [14%]; variants of uncertain significance [VUS], n = 86 [39%]; and negative, n = 101[46%]). RESULTS: Parents of children receiving P/LP or P/LP+VUS results reported significantly higher distress yet greater positive feelings than parents receiving negative results. Notably, certainty and self-efficacy increased from Timepoint 1 (median 254 days following return of results) to Timepoint 2 (median 537 days). Intrusive thoughts did not significantly differ by genetic result type or change over time; however, the factors contributing to intrusive thoughts could not be determined from the current study. DISCUSSION: These findings provide insight into how families adapt to germline genomic information following a pediatric cancer diagnosis. As precision medicine becomes increasingly embedded in pediatric oncology, structured follow-up and communication that address families' evolving informational and psychosocial needs are essential to ensure care that is scientifically precise, emotionally attuned, and centered on the family experience.

family-centered care↗

PubMed2026

Heterozygous germline mutations in MSH3, and probably MLH3, act as classical tumour suppressors, leading to excess somatic deletion mutations, signature ID4 and increased colorectal cancer risk.

BACKGROUND: MSH3 and MLH3 are non-canonical DNA mismatch repair genes, involved in repairing insertion-deletion mutations. Colorectal cancer (CRC) and adenomas have been reported in patients with bi-allelic germline MSH3 mutations, and in a very few bi-allelic MLH3 mutation carriers. OBJECTIVES: We hypothesised that germline loss-of-function MSH3 and MLH3 mutations were akin to constitutional mismatch repair deficiency (cMMRd) and Lynch syndrome, such that CRC could result from either bi-allelic germline mutations or heterozygous germline mutations after second hits. DESIGN: About 12 000 CRC and multiple polyp cases and 460 000 controls were studied. 2023 patients underwent cancer genome sequencing. RESULTS: One CRC/multiple polyp case had bi-allelic MSH3 mutations and another, bi-allelic MLH3 mutations. MSH3 and MLH3 germline heterozygotes had an increased risk of CRC (2.2-fold, p=6.6×10-5 and 1.6-fold, p=0.028, respectively), owing to somatic 'second hits' that inactivated the wildtype allele. Single second hits sometimes inactivated both MSH3 and the nearby APC gene. All CRCs with MSH3 or MLH3 deficiency were microsatellite-stable but hypermutant. Deletions of ≥2 bp were particularly increased (~12-fold) and signature ID4 was usually present (p<0.0001). CRCs from heterozygotes without 'second hits' showed no hypermutation. CONCLUSION: The phenotypes of bi-allelic MSH3 and MLH3 mutation carriers resemble some patients with cMMRd. Heterozygous germline MSH3 and MLH3 alleles have incomplete penetrance, but increase CRC risk via hypermutation, phenotypically resembling PMS2-mutant Lynch syndrome. A causal association with specific mutations has not previously been reported for ID4 in human tumours. ID4 probably does not have a single aetiology, but can result from MSH3 or MLH3 deficiency.

COLONIC POLYPS↗

PubMed2026

Evaluation of germline transmission of electroporation-mediated double gene-edited cattle lines.

Gene editing in livestock using clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) offers a promising approach for genetic improvement in cattle. This study evaluated germline transmission and mutation stability of double-knockout cattle generated by zygote electroporation. Previously reported myostatin/beta-lactoglobulin (MSTN/BLG) and newly generated α-1,3-galactosyltransferase (GGTA1/BLG) double-knockout cattle were produced using CRISPR/Cas9-mediated genome editing. Targeted deep sequencing demonstrated extensive somatic mosaicism across multiple tissues. Computer-assisted sperm analysis (CASA) demonstrated normal sperm motility in MSTN/BLG double-knockout males. Fertilization of wild-type oocytes produced heterozygous embryos, with mutation frequencies of 37.76 ± 10.74% at the MSTN locus and 54.80 ± 7.73% at the BLG locus, as assessed by T7 endonuclease I (T7E1) assay. MSTN/BLG double-knockout sperm were subsequently used for embryo production and for artificial insemination of GGTA1/BLG double-knockout females. Healthy offspring were successfully obtained (n = 3), alongside one stillborn calf. Targeted deep sequencing of all four progenies revealed highly variable allele frequencies that deviated substantially from the approximately 50% expected for heterozygous germline transmission. In contrast, whole-genome sequencing (WGS) results were consistent with Mendelian expectations, underscoring the limitations of PCR-based targeted sequencing for assessing germline transmission in mosaic founders. These results show that CRISPR/Cas9-edited embryos generated by electroporation can develop into healthy, sexually mature cattle capable of germline transmission. While variable transmission rates were observed owing to founder mosaicism, non-mosaic F1 offspring were successfully generated. However, direct, embryo-mediated gene-editing strategies remain technically and economically challenging for large-scale commercial calf production, and reports in cattle are limited. This study provides a reference for future applications of gene-edited embryos and their germline propagation.

Animals↗

PubMed2026

Incidental MSH6 Germline Pathogenic Variant Identified through Tumor-only Comprehensive Genomic Profiling in a Patient with Small Cell Lung Cancer.

A 55-year-old woman was diagnosed with limited-disease small cell lung cancer (LD-SCLC) after incidental detection of a lung nodule. First-line chemotherapy achieved partial response, but recurrence occurred after one year. During second-line therapy, comprehensive genomic profiling (CGP) revealed a germline MSH6 frameshift mutation. Although lung tumor immunohistochemistry showed the retained expression of mismatch repair (MMR) protein, a prior colon cancer specimen showed the loss of MSH6 expression and deficient MMR expression. Germline genetic testing confirmed Lynch syndrome. Cascade testing identified the same mutation in her daughter. This case outlines a tumor-to-germline workflow with testing of at-risk relatives and highlights the importance of prudent interpretation of presumed germline variants.

Humans↗

PubMed2026

Hereditary cancer: Germline testing practices across ERN GENTURIS member countries.

Germline genetic testing practices for hereditary cancer vary across the European Reference Network on Genetic Tumour Risk Syndromes (ERN GENTURIS) member countries. We surveyed experts in genetic testing from 20 EU member countries and Norway to assess multi-gene panel usage, availability of genome-wide sequencing, first-tier testing approaches, implementation of polygenic risk scores, and the roles of non-genetic healthcare professionals. National experts and members of the ERN GENTURIS completed a structured questionnaire covering founder germline pathogenic variants (gPV) testing, panel testing for common genetic tumour risk syndromes, use of whole-exome sequencing (WES) and whole-genome sequencing, polygenic risk score implementation, use of formalin-fixed paraffin-embedded tumour samples, laboratory accreditation, and the clinical roles of physicians, genetic counselors and nurses. Significant inter-country heterogeneity was observed. Most countries rely on next-generation sequencing (NGS) multi-gene panels. Founder gPV testing is first-line in a few high-prevalence populations (e.g., BRCA1/2 founders). All 21 countries offer NGS panel tests for hereditary breast and ovarian cancer, and ≥19 countries do so for colorectal and prostate cancers. However, NGS panel size and gene composition exhibit substantial variability. WES is available in 12 countries on a routine basis. Most countries implemented genetic testing on stored tumour tissue from deceased patients. In all countries, clinical geneticists can order germline genetic tests, and in 9 countries, any physician can do so. These findings show differences in accessibility to germline genetic testing of hereditary cancer in Europe. We propose EU-wide guidance via pathways, standards of care, and sharing of best practices to further optimize access to hereditary cancer genetic molecular diagnostics.

Humans↗

PubMed2026

Two cases of mosaic germline SVA insertions in SMARCB1: implications for rhabdoid tumour predisposition diagnosis.

Rhabdoid tumour predisposition syndrome (RTPS) is a highly penetrant cancer predisposition syndrome caused by germline variants in SMARCB1 or less frequently in SMARCA4. Genetic testing for this syndrome involves sequence and deletion/duplication analysis of these two genes. Standard clinical testing is limited in detecting structural variants. Here we describe two patients who tested negative on standard clinical germline panel testing for RTPS but were each found to have a mosaic germline insertion of an SVA (SINE-VNTR-Alu) element in the SMARCB1 gene by more advanced comprehensive genomic analysis. These two cases demonstrate the importance of structural variants and broader genomic sequencing for individuals suspected of having an underlying germline cancer predisposition syndrome, such as RTPS.

Journal Article↗

PubMed2025

Genomic and Immune Landscape of Pancreatic Ductal Adenocarcinoma Associated with Germline Pathogenic Variants in ATM.

PURPOSE: Germline pathogenic variants (PV) in ATM increase the risk of pancreatic ductal adenocarcinoma (PDAC), but the underlying tumor biology of PDAC associated with germline PV in ATM has not been adequately explored. EXPERIMENTAL DESIGN: Whole-genome, whole-exome, and RNA sequencing were performed on PDAC tumors from 25 germline ATM PV carriers diagnosed at Mayo Clinic between 2007 and 2017. Somatic and copy-number alterations, mutational signatures, transcriptomic subtypes, and the immune landscape were evaluated. RESULTS: High-quality whole-exome and whole-genome sequencing were obtained from 21 and 15 tumors, respectively. Biallelic inactivation of ATM was observed in 87%, KRAS PV in 90%, CDKN2A homozygous loss in 60%, and TP53 alterations in <10% of these tumors. A predominant clock-like mutational signature was present in all samples. Whole-transcriptome analysis identified that the aberrantly differentiated endocrine exocrine subtype accounted for 18% of PDAC and was consistently associated with >5-year overall survival. In addition, a 28-gene expression-based signature associated with overall survival was identified and further validated in The Cancer Genome Atlas cohort. Immune landscape analysis through CODEX identified enriched CD4 T-helper cell/tumor interactions and reduced B7H3-high cell/tumor interactions in ATM PV carriers compared with noncarriers. CONCLUSIONS: The observed absence of TP53 PV and enrichment for CDKN2A alterations in ATM tumors, along with differences in the mutational signatures, transcriptomic subtypes and immune landscape, improve our understanding of the mechanistic pathways involved in PDAC development in germline ATM PV carriers and help identify potential targeted therapeutic strategies.

Humans↗

PubMed2025

Germline variants in CDKN2A wild-type melanoma prone families.

Germline pathogenic variants in CDKN2A are well established as an underlying cause of familial malignant melanoma. While pathogenic variants in other genes have also been linked to melanoma, most familial cases remain unexplained. We assessed pathogenic germline variants in 360 cancer-related genes in 56 Norwegian melanoma-prone families. The index cases were selected based on familial history of melanoma and/or multiple primary melanomas, along with previous negative tests for pathogenic CDKN2A variants. We found 6 out of 56 index individuals to carry germline pathogenic or likely pathogenic variants in BRCA2, MRE11, ATM, MSH2, CHEK2, and AR. One family member with melanoma (not index case) carried a pathogenic variant in MAP3K6. In addition, we found a high fraction of variants previously considered benign and/or as variants of uncertain significance in xeroderma pigmentosum-related genes. In particular, XPCL48F was found in 8 indexes; thus, the allele fraction (0.07) was significantly higher than in comparable healthy populations (0.02-0.03; P-values from 0.007 to 0.014). In conclusion, we found that several melanoma-prone families have pathogenic variants in genes not usually linked to melanoma.

Humans↗

PubMed2026

GenProb-PCSM: A Simplified Weighted Germline Score for Prostate Cancer-Specific Mortality.

BACKGROUND: We previously developed a tier-based germline classification using the National Comprehensive Cancer Network (NCCN)-recommended DNA damage repair (DDR) genes and KLK3 I179T to predict prostate cancer (PCa)-specific mortality (PCSM). To provide an easier-to-use single inherited risk score while preserving gene-specific effects, we developed GenProb-PCSM. METHODS: We analyzed 14,644 men with incident PCa from the UK Biobank. The cohort was randomly divided into training (60%) and independent testing (40%) datasets. GenProb-PCSM was developed in the training cohort by integrating pathogenic variants in ten NCCN-recommended DDR genes and the KLK3 I179T variant using gene-specific weights derived from Fine-Gray competing-risk models. Performance was evaluated in the independent testing cohort by discrimination, calibration, and risk stratification. Secondary analyzes evaluated metastatic progression and the composite endpoint of metastatic progression and/or PCSM. RESULTS: Among 14,644 men with incident PCa, 1,581 died from PCa. GenProb-PCSM remained significantly associated with PCSM in the independent testing cohort (HR per SD, 1.18; 95% CI, 1.12-1.24; p < 0.001). Using predefined risk thresholds derived from the training cohort, patients in the intermediate- and high-risk groups had significantly increased risks of PCSM compared with the low-risk group (HR 1.49, 95% CI 1.22-1.84; and HR 4.04, 95% CI 2.58-6.33, respectively). GenProb-PCSM also predicted independent metastatic progression and the composite endpoint of metastatic progression and/or PCSM. CONCLUSIONS: GenProb-PCSM transforms complex germline findings into a single inherited risk score for PCSM and metastatic progression. Its simplicity and preservation of gene-specific effects may facilitate clinical implementation of germline prognostic assessment in PCa.

DNA damage repair genes↗

PubMed2026

Shared inheritance reveals landscape of somatic and germline cancer risk in TP53.

Pathogenic variants in TP53, the key tumor suppressor gene underlying Li-Fraumeni syndrome (LFS), are among the best-established causes of inherited cancer predisposition. However, large-scale sequencing has revealed that many apparently pathogenic TP53 variants detected in blood are the result of somatic clonal expansions, complicating risk interpretation. Using blood-derived whole-exome data from 469,391 UK Biobank participants, we combined the variant allele fraction (VAF) with haplotype-sharing analysis to distinguish germline and somatic TP53 variants. Germline variants were concentrated at sites linked to partial loss of p53 function and lower disease penetrance, whereas classic LFS alleles appeared to be predominantly somatically acquired. Classic LFS alleles at high VAF conferred markedly increased risk of hematological malignancy but not solid tumors, indicating an important contribution from large TP53-mutant clonal expansions. The prevalence of somatic clonal expansion also correlated with missense variant pathogenicity, suggesting that somatic activity provides an informative in vivo proxy for functional impact. These results provide new insights into TP53-associated cancer risk at the population level, demonstrate that somatic rather than germline risk predominates in middle-aged healthy adults, and provide a scalable framework for variant classification in large-scale population genomics.

Humans↗

PubMed2026

Heterozygous germline deletion in Hif3a exacerbates esophageal squamous cell carcinoma development.

Germline variations contribute to esophageal squamous cell carcinoma (ESCC) susceptibility. We identified a germline deletion (exons 7-8) in HIF3A in an ESCC family and investigated its functional impact using CRISPR/Cas9-engineered cells and Hif3a-eKO1 mice (heterozygous for exons 7-8 deletion). Multi-omics analysis of Hif3a-eKO1 and WT mice revealed dysregulated pathways in normal esophagus and during 4NQO-induced carcinogenesis, with key biomarkers validated by immunohistochemistry. Hif3a deficiency enhanced ESCC cell proliferation and invasion in vitro and accelerated 4NQO-induced tumorigenesis in vivo, with Hif3a-eKO1 mice developing more and larger neoplastic lesions. Multi-omics analysis revealed downregulation of cytokeratin-related genes (notably Krt17) and γδ T cells in normal esophagus of Hif3a-eKO1 compared with WT. Consistently reduced Krt17 expression in Hif3a-eKO1 was confirmed by both esophageal immunohistochemistry and cellular Western blot analyses. During 4NQO-induced carcinogenesis, Hif3a deficiency upregulated DNA damage response markers, including Krüppel-like factor 4 (Klf4) and ATR serine/threonine kinase (Atr). Notably, epithelial cells with abundant γH2AX foci lacked Krt17 expression, while Krt17-positive cells showed minimal γH2AX foci. Heterozygous germline Hif3a deletion (exons 7-8) may promote ESCC by disrupting esophageal barrier function-impairing Krt17-mediated epithelial integrity and reducing γδ T cells-while exacerbating genomic instability. These findings reveal ESCC predisposition mechanisms and therapeutic targets. © 2026 The Pathological Society of Great Britain and Ireland.

HIF3A↗

PubMed2026

CanVar-UK: A collaborative platform for germline interpretation in cancer susceptibility genes.

Germline variants in cancer susceptibility genes (CSGs) are typically inherited rather than arising de novo. Hence, wide cascade testing of families across geographies is common, meaning consistency in variant classification is particularly critical. Variant interpretation requires collation of variant-level data from diverse sources, as well as assembly of comprehensive clinical data, often necessitating sharing of information between genomic testing centers. Here, we describe CanVar-UK, a freely accessible web platform bespoke designed to support interpretation of germline CSG variants. CanVar-UK contains variant-level data for over 1.1 million single-nucleotide variants (SNVs), comprising all possible coding SNVs in 116 established CSGs. The data sources with which variants are annotated include in silico scores from 11 clinically relevant tools, population allele frequencies from gnomAD v4.1, case counts from multiple cohorts, including National Health Service (NHS) clinical laboratory testing, variant-level readouts from 47 selected functional and splicing datasets across 19 CSGs, genetic epidemiology studies, and live linkage to existing consensus classifications in the ClinVar database. The diagnostic discussion forum is only available to registered diagnostic scientist users. Through this, a variant-tagged email message can be dispatched in real time across the diagnostic forum community of >1,500 users, with all exchanges and classifications captured and stored in the platform. Already widely used by NHS diagnostic clinical scientists in the UK, CanVar-UK has a rapidly growing international diagnostic user base (>800 UK and >600 non-UK registered users). Survey of the NHS diagnostic user community illustrates the wide-ranging utility of CanVar-UK within their clinical workflows for interpretation of germline CSG variants.

Journal Article↗

PubMed2026

Paired Exome-Based Comprehensive Genomic Profiling and Germline Genetic Testing for Unselected Patients With Colorectal Cancer in a Multicenter Prospective Study.

BACKGROUND AND AIMS: Comprehensive genomic profiling (CGP) for tumors and germline genetic testing (GGT) inform precision therapy and clinical management of patients with colorectal cancer (CRC), and evidence is growing in support of universal paired CGP-GGT patient testing. However, the utility of combining CGP and GGT for early-stage CRC (ESC) and early-onset CRC (EOC) is unclear. METHODS: We performed a prospective, multisite study featuring GGT using an 80+ gene next-generation sequencing platform and exome-based CGP among CRC patients (unselected for age, stage, family history) receiving care at Mayo Clinic Cancer Centers between April 1, 2018, and March 31, 2020. RESULTS: A total of 150 CRC patients had GGT and exome-based CGP performed. ESC patients had an enrichment of high microsatellite instability and high tumor mutation burden. High microsatellite instability was also enriched in those with smoking history, and in tumors with mutated BRAF, homologous recombination deficiency, or at least 1 variant in the rat sarcoma virus pathway. Moreover, patients with smoking history were enriched in BRAF and other Tier 1 or 2 variants overall. Sixteen percent of patients harbored a pathogenic germline variant, most frequent being in Lynch syndrome genes. Paired GGT and CGP testing had high rates of clinically significant findings (≈70%) with the most frequent being high tumor mutation burden status. Pathway and mutational signature analysis revealed frequent CGP mutations in DNA repair and cell cycle pathways. CONCLUSION: These data suggest that universal, combined GGT-CGP increases clinical utility for EOC and ESC patients. This is key for EOC patients who tend to experience poorer outcomes. CGP-GGT expedites germline resolution for tumor mutations in hereditary cancer genes, reducing delays and facilitating identification of relevant therapies, clinical trials, and management recommendations.

Colorectal Cancer↗