Search Results (73)

Background/Objectives: Germline BRCA1 mutations account for ~15–20% of hereditary breast and ovarian cancer (HBOC) cases. While most are small sequence variants, structural rearrangements also contribute significantly to the pathogenic landscape. Conventional diagnostic workflows often miss such events, underscoring the need for comprehensive approaches. Here, we report a previously undescribed pathogenic mechanism—a transposon-mediated processed transcript insertion—expanding the mutational spectrum underlying hereditary breast cancer susceptibility. Methods: The studied case was discovered during our germline genotyping routine: next-generation sequencing followed by library preparation with a custom hereditary cancer panel. The identified variant was validated by orthogonal sequencing and multiplex ligation-dependent probe amplification (MLPA). RNA-level functional assays, including nonsense-mediated decay inhibition, were conducted to assess transcript stability. Constitutional origin was confirmed by analysis of multiple normal tissues, and tumor material was evaluated for loss of heterozygosity (LOH). Results: NGS detected a 700 bp insertion in exon 16 of BRCA1, corresponding to a complete processed transcript of RPL18A. The insertion caused a frameshift and premature stop codon, triggering degradation of the aberrant transcript. The variant was present in multiple somatic tissues, and its heritable nature was further confirmed by genotyping a first-degree relative, who was also found to carry the insertion. Tumor DNA analysis revealed strong LOH with retention of the variant allele. Conclusions: This study identifies, for the first time, a heritable processed transcript insertion as a pathogenic event in BRCA1. Such variants are undetectable by conventional diagnostic workflows lacking structural variant analysis, highlighting the importance of comprehensive approaches for accurate diagnosis and genetic counselling in hereditary cancer syndromes. Full article

Background/Objectives: Accurate detection of all classes of genomic structural variants (SVs), including chromosomal rearrangements and copy number alterations (CNAs), is essential for the diagnosis and classification of hematologic neoplasms. Conventional cytogenetic methods currently serve as routine clinical tools for detecting SVs. However, each commonly used cytogenetic test has specific limitations, and sequential application of these different tests may delay timely diagnosis and treatment. Methods: In this study, we evaluated the feasibility and utility of genomic proximity mapping (GPM), a novel high-throughput chromosome conformation capture (Hi-C)-based next-generation sequencing (NGS) method, to identify chromosomal and genetic aberrations in hematologic neoplasms in the clinical setting. GPM was performed on 18 cases of hematologic neoplasms (fresh/frozen cells or formalin-fixed paraffin-embedded tissue), and concordance with other methodologies was assessed, including karyotyping, FISH, RT-PCR, chromosomal microarray analysis (CMA), and/or RNA sequencing. Results: GPM reliably detected balanced and unbalanced chromosomal rearrangements, including chimeric gene fusions and gene juxtapositions, with 95.2% concordance with previously applied methods in cases with >10% tumor burden. Additionally, GPM can detect CNAs and copy-neutral loss of heterozygosity (cnLOH) simultaneously in a single assay. Furthermore, detection of genomic rearrangements not identified by other methods improved the accuracy of disease classification. Conclusions: These findings demonstrate that GPM is a powerful method for identifying clinically actionable variants in hematologic neoplasms, overcoming some limitations of current cytogenetic technologies and improving the diagnostic accuracy and classification in challenging cases Full article

Studies of the genomic stability of Ewing sarcoma (EwS) have produced contradictory findings. While they are generally characterized by low mutation rates of individual genes, several cases exhibit genomic alterations that manifest as chromosomal gains and losses. Taken together, these alterations represent independent biomarkers for EwS, such as loss of heterozygosity (LOH) or an altered genome. Patients with primary EwS tumors with fewer than three copy number alterations (CNAs) have a better prognosis than those with more CNAs. The functional mechanisms underlying this chromosomal instability are not yet clear. However, there are indications that this may be directly caused by the EWSR1::ETS translocations that are characteristic of EwS. The transcriptional behavior of the chimeric transcription factor EWSR1-FLI1 leads to the formation of R-loop DNA–RNA hybrids that form when RNA binds back to DNA during transcription and increased replication stress, which may result in structural chromosomal changes. Additionally, the formation of EWSR1 fusion genes in EwS results in the loss of one or both wild-type EWSR1 alleles in sarcoma cells. As chromosome segregation has been observed under loss of wild-type EWSR1, EWSR1 loss has been proposed as a potential source of LOH. So, it is highly probable that a chromosomal translocation and the subsequent formation of the EWSR1-ETS fusion protein cause the genomic alterations in EwS. This indicates that targeted therapy should be directed against the CNA and LOH biology caused by the fusion protein. Full article

Homologous recombination deficiency (HRD) is a pivotal biomarker in precision oncology, driving therapeutic strategies for ovarian and breast cancers through impaired DNA double-strand break repair. This narrative review synthesizes recent advances (2021–2025) in HRD’s biological basis, prevalence, detection methods, and clinical implications, focusing on high-grade serous ovarian carcinoma (HGSOC; ~50% HRD prevalence) and triple-negative breast cancer (TNBC; 50–70% prevalence). HRD arises from genetic (BRCA1/2, RAD51C/D, PALB2) and epigenetic alterations (e.g., BRCA1 methylation), leading to genomic instability detectable via scars (LOH, TAI, LST) and mutational signatures (e.g., COSMIC SBS3). Advanced detection integrates genomic assays (Myriad myChoice CDx, Caris HRD, FoundationOne CDx), functional assays (RAD51 foci), and epigenetic profiling, with tools like HRProfiler and GIScar achieving >90% sensitivity. HRD predicts robust responses to PARP inhibitors (PARPi) and platinum therapies, extending progression-free survival by 12–36 months in HGSOC. However, resistance mechanisms (BRCA reversion, SETD1A/EME1, SOX5) and assay variability (60–70% non-BRCA concordance) pose challenges. We propose a conceptual framework in ^{Section 10}, integrating multi-omics, methylation analysis, and biallelic reporting to enhance detection and therapeutic stratification. Regional variations (e.g., Asian cohorts) and disparities in access underscore the need for standardized, cost-effective diagnostics. Future priorities include validating novel biomarkers (SBS39, miR-622) and combination therapies (PARPi with ATR inhibitors) to overcome resistance and broaden HRD’s applicability across cancers. Full article

Chromosomal microarray analysis (CMA) was performed for 40 patients with B-ALL undergoing treatment according to the ALL-2016 protocol to investigate the copy number alterations (CNAs) and copy neutral loss of heterozygosity (cnLOH) associated with minimal residual disease (MRD)-positive remission. Aberrations involving over 20,000 genes were identified, and a random forest approach was applied to isolate a subset of genes whose CNAs and cnLOH are significantly associated with poor therapeutic response. We have assembled the triple matched healthy population data and used that data as a reference, but not as a matched control. We identified a recurrent cluster of cnLOH in the 19q13.2–19q13.31 region, significantly enriched in MRD-positive patients (70% vs. 47% in the reference group vs. 16% in MRD-negative patients). This region includes the pregnancy-specific glycoprotein (PSG) gene family and the oncogene ERF, suggesting a potential role in leukemic persistence and treatment resistance. Additionally, we observed significant deletions involving 7p22.3 and 16q13, often as part of large-scale losses affecting almost the entire chromosomes 7 and 16, indicative of global chromosomal instability. These findings highlight specific genomic regions potentially involved in therapy resistance and may contribute to improved risk stratification in B-ALL. Our findings emphasize the value of high-resolution CMA in diagnostics and risk stratification and suggest that PSG genes and other candidate genes could serve as biomarkers for predicting treatment outcomes. Full article

Background: In childhood acute lymphoblastic leukemia (ALL), in addition to classical chromosomal abnormalities, loss of heterozygosity (LOH), including copy-neutral LOH, is also observed. While LOH has been described in the literature, its clinical relevance in pediatric ALL remains unclear. The aim of this study is to identify and analyze patterns of LOH, assess their frequency, and evaluate their association with clinical characteristics and early treatment response during the induction phase of the ALL protocol. Methods: The study included 853 pediatric ALL patients, of whom 120 had B-ALL LOH+ and 58 had T-ALL LOH+. LOH was analyzed using CytoScan HD SNP microarrays. Patients were stratified using multiple correspondence analysis (MCA) and hierarchical clustering on principal components (HCPC), which identified three genetically and clinically distinct clusters. Results: In B-ALL, two clusters with extensive LOH—particularly involving chromosome 9—were associated with poor prognosis and suboptimal response to therapy. In contrast, Cluster 2, characterized by CDKN2A duplication and rare LOH, showed a favorable clinical course. In T-ALL, Cluster 1 had LOH in CDKN2A but favorable outcomes; Cluster 2 exhibited biallelic CDKN2A deletion and aggressive disease; Cluster 3 lacked CDKN2A alterations and showed a genetically stable profile. LOH was common on chromosomes not typically affected by trisomy and rare on those gained. Conclusions: Our study indicates that LOH profiling can positively influence patient stratification by identifying high-risk subgroups, inform prognosis by highlighting unfavorable genetic alterations, and help predict poor treatment response in specific clinical profiles. Full article

Ovarian cancer (OC) is a highly heterogeneous malignancy, often characterized by complex genomic alterations that drive tumor progression and therapy resistance. In this paper, we report a novel de novo BRCA2 germline variant NM_000059.3:c.(8693_8695delinsGT) associated with early-onset OC that featured two regions with differential MMR (Mismatch Repair) gene expression. To date, only six cases of de novo BRCA2 variants have been reported, none of which were associated with early-onset high-grade serous OC. The immunohistochemical analysis of MMR genes revealed two distinct tumor areas, separated by a clear topographic boundary, with the heterogeneous expression of MLH1 and PMS2 proteins. Seventy-five percent of the tumor tissue showed positivity, while the remaining 25% exhibited a complete absence of expression, underscoring the spatial variability in MMR gene expression within the tumor. Integrated comparative spatial genomic profiling identified several tumor features associated with the genetic variant as regions of loss of heterozygosity (LOH) that involved BRCA2 and MLH1 genes, along with a significantly higher mutational tumor burden in the tumor area that lacked MLH1 and PMS2 expression, indicating its further molecular evolution. The following variants were acquired: c.6572C>T in NOTCH2, c.1852C>T in BCL6, c.191A>T in INHBA, c.749C>T in CUX1, c.898C>A in FANCG, and c.1712G>C in KDM6A. Integrated comparative spatial proteomic profiles revealed defects in the DNA repair pathways, as well as significant alterations in the extracellular matrix (ECM). The differential expression of proteins involved in DNA repair, particularly those associated with MMR and Base Excision Repair (BER), highlights the critical role of defective repair mechanisms in driving genomic instability. Furthermore, ECM components, such as collagen isoforms, Fibrillin-1, EMILIN-1, Prolargin, and Lumican, were found to be highly expressed in the MLH1/PMS2-deficient tumor area, suggesting a connection between DNA repair deficiencies, ECM remodeling, and tumor progression. Thus, the identification of the BRCA2 variant sheds light on the poorly understood interplay between DNA repair deficiencies and ECM remodeling in OC, providing new insights into their dual role in shaping tumor evolution and suggesting potential targets for novel therapeutic strategies. Full article

DNA methylation of tumor suppressor genes in cancer is known to be a mechanism for silencing gene expression, but much remains unknown about its extent and relationship to somatic variants at the DNA sequence level. In this study, we comprehensively analyzed DNA methylation and somatic variants of all gene regions across the genome of the major tumor suppressor genes, APC, TP53, SMAD4, and mismatch repair genes in colorectal cancer using a novel next-generation sequencing-based analysis method. The Targeted Methyl Landscape (TML) shows that DNA hypermethylation patterns of these tumor suppressor genes in colorectal cancer are more complex and widespread than previously thought. Extremely high levels of DNA methylation were observed in relatively long regions around exon 1A of APC and exon 1 and surrounding region of MLH1. DNA hypermethylation occurred whether or not somatic DNA variants were present in the tumor. Even in tumors where the loss of heterozygosity has been demonstrated by somatic variants alone, additional methylation of the same gene can occur. Our data demonstrate that somatic variants and hypermethylation of these tumor suppressor genes were considered independent, parallel events, not exclusive of each other or having one event affecting the other. Full article

Background: Unilateral (uVS) and bilateral vestibular schwannoma (bVS) are distinct disease types, yet share tumorigenic features. This study examined causative genetic alterations in three groups: patients with NF2-related schwannomatosis (NF2), young patients with uVS (≤30 years), and older patients with uVS (≥40 years). Methods: Lymphocyte and vestibular schwannoma DNA was genetically analyzed. Outcomes included gene involvement, pathogenicity classification, variant type, effect, and location, and loss of heterozygosity (LOH) of chromosome 22. Results: Among 93 patients, 17% had NF2, 39% were ≤30 years with uVS, and 44% were ≥40 years with uVS. In all patients with NF2 (100%), two or more hits were detected in the tumor DNA, whereas patients with uVS had a slightly lower detection rate (89–98%). NF2-related tumors had a higher frequency of nucleotide variants (76%), while LOH events were more common in uVS (64–69%). Variants were mostly identified in NF2, with nonsense variants over-represented in patients with NF2 (38%) and frameshift variants more prevalent in uVS (44–51%). Conclusions: Biallelic NF2 inactivation primarily drives vestibular schwannoma tumorigenesis. In patients with NF2, two pathogenic NF2 variants or one NF2 variant with LOH are common, whereas patients with uVS often exhibit one NF2 variant with LOH. Additionally, variant types differ between patient groups. Full article

Background: The 5-year prognosis of non-high-risk neuroblastomas is generally good (>90%). However, a proportion of patients show progression and succumb to their disease. We aimed to identify molecular aberrations (not incorporated in the current risk stratification) associated with overall survival (OS) and/or event-free survival (EFS) in patients diagnosed with non-high-risk neuroblastoma. Methods: We conducted a systematic search in PubMed, Embase, Cochrane and Google Scholar. Two reviewers independently and blindly screened titles/abstracts, references of protocols/reviews and full texts. Risk of bias was assessed using a customized Quality in Prognostic Studies tool. Applicability was assessed using a tool designed by the researchers. GRADE criteria were used to determine quality of evidence. Results: Sixteen studies (4718 patients) were included. A segmental chromosomal aberration (SCA) profile was associated with lower survival. 1p loss of heterozygosity (LOH) and 17q gain were associated with lower OS and EFS. 1p deletion and 2p gain were associated with lower OS, but this was not the same for EFS. 3p deletion was not associated with worse outcome. Quality of evidence was downgraded because of imprecision and publication bias and upgraded because of moderate/large effect, resulting in a moderate quality of evidence. Conclusion: The association of 1p LOH, 1p deletion, 2p gain and 17q gain with OS and EFS suggests that these SCAs may be added to the risk stratification to identify non-high-risk neuroblastomas with worse prognosis. Full article

Major histocompatibility complex (MHC) class-I molecules (or Human Leucocyte Antigen class-I) play a key role in adaptive immunity against cancer. They present specific tumor neoantigens to cytotoxic T cells and provoke an antitumor cytotoxic response. The total or partial loss of HLA molecules can inhibit the immune system’s ability to detect and destroy cancer cells. Loss of heterozygosity (LOH) is a common irreversible genetic alteration that occurs in the great majority of human tumors, including breast cancer. LOH at chromosome 6, which involves HLA genes (LOH-HLA), leads to the loss of an HLA haplotype and is linked to cancer progression and a weak response to cancer immunotherapy. Therefore, the loss of genes or an entire chromosomal region which are critical for antigen presentation is of particular importance in the search for novel prognostic and clinical biomarkers in breast cancer. Here, we review the role of LOH-HLA in breast cancer, its contribution to an understanding of cancer immune escape and tumor progression, and discuss how it can be targeted in cancer therapy. Full article

Comprehensive next-generation sequencing (NGS) assays enable the identification of clinically relevant mutations, enhancing the capability for targeted therapeutic interventions. In addition, genomic alterations driving the oncogenic roadmap and leading to resistance mechanisms are reshaping precision oncology. We report the workflow and clinical and technical validation of the OncoIndx^® NGS platform—a comprehensive genomic profiling (CGP)-based assay for pan-cancer investigation. We evaluated the concordance between the OncoIndx^® test findings and clinically established hotspot detection using SeraSeq reference standards. OncoIndx is a hybridization capture-based NGS assay for the targeted deep sequencing of all exons and selected introns of 1080 cancer-related genes. We show the outcome in the form of tier I and tier II single nucleotide variants (SNVs), copy number alterations (CNAs), and specific gene fusions. OncoIndx^® also informs genome-wide tumor mutational burden (TMB), microsatellite instability (MSI), homologous recombination deficiency (HRD), and genomic loss of heterozygosity (gLOH). A total of 63 samples were utilized for validation with reference standards, clinical samples, and orthogonal assessment for genomic alterations. In addition, 49 cross-laboratory samples were validated for microsatellite instability (MSI), and for the tumor mutation burden (TMB), 18 samples as reference standards, 6 cross-laboratory samples, and 29 TCGA samples were utilized. We show a maximum clinical sensitivity of 98% and a positive predictive value (PPV) of 100% for the clinically actionable genomic variants detected by the assay. In addition, we demonstrate analytical validation with the performance of the assay, limit of detection (LoD), precision, and orthogonal concordance for various types of SVs, CNAs, genomic rearrangements, and complex biomarkers like TMB, MSI, and HRD. The assay offers reliable genomic predictions with the high-precision detection of actionable variants, validated by established reference standards. Full article

Small-cell neuroendocrine cervical carcinoma (SCNCC) is a rare yet aggressive gynecological malignancy associated with dismal clinical outcomes. Its rarity has led to a limited number of retrospective studies and an absence of prospective research, posing significant challenges for evidence-based treatment approaches. As a result, most gynecologic oncology centers have limited experience with this tumor, emphasizing the urgent need for a comprehensive review and summary. This article systematically reviews the pathogenesis, immunohistochemical and molecular characteristics, prognostic factors, and clinical management of gynecologic SCNCC. We specifically focused on reviewing the distinct genomic characteristics of SCNCC identified via next-generation sequencing technologies, including loss of heterozygosity (LOH), somatic mutations, structural variations (SVs), and microRNA alterations. The identification of these actionable genomic events offers promise for discovering new molecular targets for drug development and enhancing therapeutic outcomes. Additionally, we delve deeper into key clinical challenges, such as determining the optimal treatment modality between chemoradiation and surgery for International Federation of Gynecology and Obstetrics (FIGO) stage I phase patients within a precision stratification framework, as well as the role of targeted therapy within the homologous recombination (HR) pathway, immune checkpoint inhibitors (ICIs), and prophylactic cranial irradiation (PCI) in the management of SCNCC. Finally, we anticipate the utilization of multiple SCNCC models, including cancer tissue-originated spheroid (CTOS) lines and patient-derived xenografts (PDXs), to decipher driver events and develop individualized therapeutic strategies for clinical application. Full article

Background: MUTYH germline monoallelic variants have been detected in a number of patients affected by breast/ovarian cancer or endometrial cancer, suggesting a potential susceptibility role, though their significance remains elusive since the disease mechanism is normally recessive. Hence, the aim of this research was to explore the hypothesis that a second hit could have arisen in the other allele in the tumor tissue. Methods: we used Sanger sequencing and immunohistochemistry to search for a second MUTYH variant in the tumoral DNA and to assess protein expression, respectively. Results: we detected one variant of unknown significance, one variant with conflicting interpretation of pathogenicity and three benign/likely benign variants; the MUTYH protein was not detected in the tumor tissue of half of the patients, and in others, its expression was reduced. Conclusions: our results fail to demonstrate that germinal monoallelic MUTYH variants increase cancer risk through a LOH (loss of heterozygosity) mechanism in the somatic tissue; however, the absence or partial loss of the MUTYH protein in many tumors suggests its dysregulation regardless of MUTYH genetic status. Full article

Pancreatic cystic disease, including duct dilation, represents precursor states towards the development of pancreatic cancer, a form of malignancy with relatively low incidence but high mortality. While most of these cysts (>85%) are benign, the remainder can progress over time, leading to malignant transformation, invasion, and metastasis. Cytologic diagnosis is challenging, limited by the paucity or complete absence of cells representative of cystic lesions and fibrosis. Molecular analysis of fluids collected from endoscopic-guided fine-needle aspiration of pancreatic cysts and dilated duct lesions can be used to evaluate the risk of progression to malignancy. The basis for the enhanced diagnostic utility of molecular approaches is the ability to interrogate cell-free nucleic acid of the cyst/duct and/or extracellular fluid. The allelic imbalances at tumor suppressor loci and the selective oncogenic drivers are used clinically to help differentiate benign stable pancreatic cysts from those progressing toward high-grade dysplasia. Methods are discussed and used to determine the efficacy for diagnostic implementation. Here, we report the analytical validation of methods to detect causally associated molecular changes integral to the pathogenesis of pancreatic cancer from pancreatic cyst fluids. Full article