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PubMed2026

A CCNA1 Missense Variant Associated With Chromatid Non-Disjunction in Abnormal-Headed Sperm and Male Infertility.

BACKGROUND: Macrozoospermia is a rare form of teratozoospermia characterized by tetraploids, large-headed spermatozoa with multiple flagella, usually caused by bi-allelic AURKC mutations. The etiology of atypical phenotypes with a lower proportion of large headed spermatozoa and single flagella however often remains unresolved. OBJECTIVE: To investigate the genetic cause of severe sperm-head abnormalities with moderate macrozoospermia without multiflagellated spermatozoa in a patient with repeated ICSI failure. An infertile male with three failed ICSI attempts underwent semen analysis, revealing complete teratozoospermia, including 25% macrocephalic spermatozoa. METHODS: Multi-probe FISH targeting chromosomes 13, 18, 21, X, Y assessed chromosomal segregation. Whole-exome sequencing (WES) was performed to identify a candidate variant associated with meiotic abnormalities. RESULTS: FISH analysis revealed a high proportion of spermatozoa with n (23) chromosomes and 2c DNA content, consistent with sister chromatid non-disjunction during meiosis II. WES identified a homozygous missense variation in CCNA1, coding for a protein described to be essential for meiotic progression and chromatin remodeling in male germ cells. DISCUSSION: The variant affects a highly conserved residue within a functional domain and is predicted to be deleterious. This study establishes the first clinical association between CCNA1 mutations and chromatid non-disjunction in human spermatogenesis. It highlights the limitations of current morphology-based diagnostic thresholds and supports cytogenetic and genomic assessment for severe teratozoospermia (especially head abnormalities) and ART failure. CONCLUSION: Expanding genetic screening panels to include CCNA1 may improve diagnostic precision and clinical management in atypical macrozoospermia cases.

ART failure↗
PubMed2026

Molecular profiling of pediatric medulloblastoma in Kazakhstan: Genomic alterations, subgroup distribution, and survival.

Medulloblastoma is the most common malignant pediatric brain tumor and comprises biologically distinct molecular subgroups with different clinicopathologic and prognostic characteristics. Molecular data from Kazakhstan and other underrepresented regions remain limited, and practical approaches for molecular subgroup assignment using formalin-fixed, paraffin-embedded (FFPE) material are needed in settings where advanced molecular classification is not routinely available. We retrospectively analyzed 40 pediatric medulloblastomas diagnosed between 2015 and 2024 at the Corporate Fund "University Medical Center," Kazakhstan. Archived FFPE tumor material underwent histologic review, immunohistochemical evaluation (β-catenin, YAP1, and GAB1), and whole-exome sequencing. Tumors were assigned to WNT, SHH, or non-WNT/non-SHH categories using a combined morphologic, immunophenotypic, and genomic framework, and clinicopathologic variables and overall survival were evaluated across subgroups. WNT medulloblastomas (n = 7, 17.5%) showed the most canonical profile, characterized by classic histology, uniform β-catenin nuclear positivity, recurrent CTNNB1/APC alterations, and frequent chromosome 6 loss. SHH medulloblastomas (n = 10, 25.0%) were enriched for desmoplastic/nodular morphology, frequent YAP1/GAB1 expression, pathogenic PTCH1/SUFU alterations, and additional events involving TP53, TERT, and focal amplifications in a subset. Non-WNT/non-SHH medulloblastomas (n = 23, 57.5%) showed the greatest genomic heterogeneity, including frequent i17q and broader structural complexity. Clinically, WNT tumors occurred predominantly in older children and had the most favorable survival, whereas non-WNT/non-SHH tumors were the only subgroup associated with metastatic disease at presentation and showed the poorest long-term survival. Overall, pediatric medulloblastoma in this cohort demonstrated subgroup-specific patterns consistent with established biology. The integration of pathology, immunohistochemistry, and sequencing enabled clinically meaningful molecular stratification. These findings expand evidence from an underrepresented setting and support pragmatic, resource-adapted profiling in routine practice.

Kazakhstan↗
PubMed2026

Novel Germline ELP1 Splice-Acceptor Variant in NF1-Negative Optic Pathway Glioma: Expanding the Clinical Spectrum Associated With ELP1 Variation.

We report a 7-year-old boy with NF1-negative optic pathway glioma harboring a novel germline ELP1 splice-acceptor variant (NM_003640.5:c.2205-2A>G) identified by whole-exome sequencing. The variant was likely pathogenic (ACMG/AMP: PVS1, PM2) and inherited from an asymptomatic father, consistent with incomplete penetrance, expanding the limited evidence linking germline ELP1 variation to gliomas.

Humans↗
PubMed2026

Expanding the Clinical Spectrum of DHX30-Related Neurodevelopmental Disorder: A Case Report and a Scoping Review.

BACKGROUND: Whole exome sequencing (WES) has improved diagnostic rates for neurodevelopmental disorders (NDDs) while introducing challenges in novel variant interpretation. DHX30-related NDD (DHX30-NDD) is a recently described condition with an evolving phenotypic spectrum. OBJECTIVES: To expand the understanding of the DHX30-NDD genotype-phenotype spectrum by integrating a case-based WES interpretation with a scoping review. METHODS: We performed comprehensive genetic analysis (karyotyping, microarray, WES) on a proband with global developmental delay (GDD). A systematic literature search of PubMed/MEDLINE, Scopus and Google Scholar from database inception to April 2026 identified 10 publications including 51 individuals with DHX30-NDD. Clinical and genetic data were extracted to characterize the genotype-phenotype spectrum. RESULTS: The proband presented with GDD and right microtia, harbouring a de novo heterozygous pathogenic DHX30 missense variant (c.1478G > A; p.Arg493His), confirming DHX30-NDD. To our knowledge, this is the first reported individual with DHX30-NDD and microtia. The scoping review confirmed DHX30 variants are formed predominantly de novo and affected both sexes (22 males; 29 females). Hallmark manifestations were motor delay (50/51; 98.0%), GDD/ID (48/49; 98.0%), hypotonia (48/51; 94.1%), feeding difficulties (38/51; 74.5%), ataxia (17/23; 73.9%), abnormal brain imaging (36/49; 73.5%) and absent expressive language (35/48; 72.9%). Digital anomalies (31/51; 60.8%), eye anomalies (28/51; 54.9%), autistic behaviours (24/44; 54.5%), sleep disturbances (26/51; 51.0%), joint hypermobility (25/51; 49.0%), microcephaly (23/51; 45.1%) and ear anomalies (22/51; 43.1%) were also frequent. CONCLUSIONS: This study potentially expands the phenotypic spectrum of DHX30-NDD, highlights the clinical utility of WES for diagnosing GDD and underscores the importance of ongoing WES reanalysis for evolving variant interpretation.

DHX30↗
PubMed2024

SLC12A1 variant c.1684+1 G>A causes Bartter syndrome type 1 by promoting exon 13 skipping.

BACKGROUND: Bartter syndrome type 1, an autosomal recessive genetic disorder, is caused by pathogenic loss-of-function variants in the SLC12A1 gene. It is characterized by metabolic alkalosis and prenatal-onset polyuria leading to polyhydramnios. METHODS: We identified pathogenic gene in a 12-day-old newborn boy with Bartter syndrome type 1 using whole-exome sequencing. Sanger sequencing validated the identified variants. A minigene assay was performed to investigate the effect of a novel splice site variant on pre-mRNA splicing. RESULTS: We found a compound heterozygous variants in the SLC12A1 gene, consisting of a known pathogenic missense mutation (NM_000338: c.769 G>A; p.Gly257Ser) and a novel splice site variant (c.1684+1 G>A). In silico predictions and an in vitro minigene splicing assay demonstrated that the splicing variant c.1684+1 G>A abolished a consensus splice donor site of SLC12A1 intron 13, resulting in complete exon 13 skipping, translational frameshift, and premature termination codon, ultimately leading to loss of SLC12A1 function. CONCLUSION: Using a cell-based in vitro assay, we revealed the aberrant effect of the pathogenic splicing variant SLC12A1 c.1684+1 G>A on pre-mRNA splicing. Our findings expand the gene mutation spectrum of Bartter syndrome type 1, providing a basis for genetic diagnosis and the development of genetic medicines.

Humans↗
PubMed2025

Biallelic loss-of-function variants in C19orf44 lead to retinal degeneration.

BACKGROUND: Inherited retinal diseases (IRDs) are a group of disorders often resulting in progressive vision loss, ultimately leading to blindness. A significant portion of their genetic causes remain unresolved, partly due to undiscovered disease-associated genes or variants. This study aimed to identify novel genetic links to IRDs. METHODS: All patients underwent comprehensive ophthalmological evaluation, including retinal imaging (fundus autofluorescence and macular optical coherence tomography) and electroretinogram testing. Whole exome sequencing and whole genome sequencing were performed on patients with clinically unsolved IRD, and data were analysed using an in-house pipeline to identify causal variants. Subsequently, Sanger sequencing was performed to confirm identified variants. RESULTS: Three unrelated patients from Europe, Middle East and East Asia were identified with unique late-onset retinal degeneration (Stargardt-like phenotype) associated with biallelic loss-of-function (LoF) variants in C19orf44 (HGNC: 26141), a gene of unknown function. The homozygous variant NM_032207.2:c.549_550del;p.Ser185Profs*2 was identified in two unrelated patients (European and Middle Eastern). Moreover, an East Asian patient had likely compound heterozygous LoF variants (NM_032207.2:c.1168C>T;p.Gln390*/c.976_977del;p.Leu326Lysfs*15). CONCLUSIONS: Our findings establish C19orf44 as a novel disease-causing gene for IRD with Stargardt-like phenotype, expanding the genetic landscape of retinal degeneration.

Humans↗
PubMed2026

Biallelic pathogenic variants in FLNB are associated with paediatric steroid-resistant nephrotic syndrome via podocyte cytoskeletal dysfunction.

BACKGROUND: Steroid-resistant nephrotic syndrome (SRNS) is a severe paediatric kidney disease and a leading cause of end-stage kidney disease in children, with a high genetic contribution. While over 80 monogenic causes of SRNS have been identified, a significant proportion of affected patients still lack a clear genetic diagnosis, indicating that additional causative genes remain to be discovered. METHODS: Through whole-exome sequencing of a paediatric SRNS cohort, we identified three probands carrying biallelic FLNB pathogenic variants. Sanger sequencing was performed for familial cosegregation verification and ACMG classification. Expression of Filamin B, Nephrin and Synaptopodin in renal tissues was assessed by immunohistochemistry/immunofluorescence. Wild-type and patient-derived variant FLNB plasmids were constructed and transfected into HEK293T cells and immortalised human podocytes (HPCs). The effects of these variants on protein expression, localisation and cytoskeletal organisation were assessed by western blotting and immunofluorescence. FLNB expression in HPCs was silenced using shRNA to evaluate the impact on podocyte marker proteins, cytoskeletal integrity and migratory capacity. A zebrafish flnb knockdown model was employed to validate its effects on renal development. RESULTS: All three probands presented with isolated SRNS without skeletal developmental abnormalities, and renal tissues showed significantly reduced Filamin B protein expression. In vitro, p.L117P and p.M1803L variants led to markedly reduced protein expression, while p.R470L and p.K2586R induced perinuclear aggregation of Filamin B accompanied by F-actin rearrangement. FLNB silencing led to downregulation of Nephrin and Synaptopodin, cytoskeletal disorganisation and impaired cell migration. Zebrafish flnb knockdown exhibited pericardial oedema, defective nephron development and abnormal podocyte foot processes. CONCLUSION: We report for the first time that biallelic FLNB pathogenic variants are associated with paediatric SRNS by disrupting Filamin B expression, cytoskeletal integrity and podocyte function, providing evidence that FLNB is a novel monogenic cause of SRNS.

Humans↗
PubMed2025

Ras-MAPK pathway in patients with lupus nephritis.

BACKGROUND: Pathogenic mutations in genes encoding components of the Ras/mitogen-activated protein kinase (Ras-MAPK) pathway cause RASopathy. Here, we describe five unrelated patients with SLE carrying mutations associated with RASopathy and investigate the activity of the Ras-MAPK pathway. METHODS: Pathogenic variants were identified by whole-exome/whole-genome sequencing. The activity of the Ras-MAPK pathway in peripheral blood mononuclear cells (PBMC) and kidneys was evaluated using RNA sequencing and datasets from the nephroseq database, respectively. RESULTS: Five (likely) pathogenic variants in four Ras-MAPK genes were identified, including NRAS: c.G38A: p.G13D; ARAF: c.C1435T: p.R479C; KRAS: c.T341C: p.V114A; PTPN11: c.G455A: p.R152H and NRAS: c.G34A: p.G12S. Kidney injury is the main feature, presenting with nephrotic syndrome (2/5), proteinuria and haematuria (2/5). Acute kidney injury and rapidly progressive nephritic syndrome were noted in one patient each. Other clinical features included mucocutaneous lesions (5/5), cardiac involvement (4/5) and arthralgia (3/5). Laboratory abnormalities included hypocomplementaemia (5/5), presence of antiphospholipid antibodies (4/5), decreased regulatory T cells (3/3), pancytopenia (3/5) and persistent monocytosis (2/5). Kidney biopsy revealed lupus nephritis. Most patients responded well to standard therapy, with the exception of the patient with the NRAS p.G13D mutation who died. The Ras-MAPK pathway was activated in both PBMC and kidney of patients with LN as indicated by increased expression of NRAS, KRAS, RIT1, MRAS, PPP1CB, SHOC2, SOS2 and MAP2K1, as well as decreased expression of negative regulators of the Ras-MAPK pathway, CBL, LZTR1 and NF1. CONCLUSION: Kidney involvement may be the main feature of the clinical spectrum of RASopathy. Genetic screening should be considered for patients with early onset lupus.

Humans↗
PubMed2026

Functional Validation of a Novel Homozygous TTN Splice-Site Variant Reveals Aberrant Splicing in Hypertrophic Cardiomyopathy.

The TTN gene encodes a crucial structural protein within cardiac sarcomeres, and its variants may contribute to hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy; however, phenotype and genotype are different. Whole-exome sequencing (WES) was conducted on a Chinese proband diagnosed with HCM. In silico splicing prediction tools and minigene assays were employed to investigate the impact of the identified variant on mRNA splicing. A literature review was performed to retrieve and analyze previously reported splicing variants in the TTN gene associated with HCM. A 42-year-old male proband presented with nonobstructive HCM and paroxysmal atrial arrhythmias. A novel homozygous TTN variant was found, predicted to cause a 14-base pair deletion at a splice acceptor site. Two asymptomatic offspring were found to carry the heterozygous variant. Based on variant interpretation guidelines, the variant met the PM2_supporting criterion and was classified as a variant of uncertain significance (VUS). The predicted aberrant splicing effect was subsequently confirmed by the minigene splicing assay, demonstrating altered pre-mRNA splicing leading to an in-frame insertion/deletion (p.Arg32498_Glu32504delinsGln). Functional verification confirmed that this mutation conforms to the PM4 criterion, suggesting that it can be reclassified as a tepid VUS (scoring 3 points). The functional result might provide pathogenic evidence. We also reviewed 28 previously reported splicing variants in TTN associated with HCM. Of these, 57.1% (16/28) localized to the I-band region, whereas 21.4% (6/28) were situated in the A-band domain of titin. Notably, 21.4% (6/28) co-occurred with pathogenic variants in other sarcomeric genes (MYH7 or MYBPC3), correlating with more severe clinical phenotypes. Reclassification and reinterpretation of the variants revealed that none met the level of likely pathogenic or higher. The present case contributes a homozygous splice-site variant with experimentally confirmed aberrant splicing and an in-frame protein alteration in titin. The focus of this report is the Mendelian genetic basis of the proband's cardiomyopathy phenotype, and our data provide additional case-level and functional evidence for a possible role of specific TTN splicing defects in HCM.

Humans↗
PubMed2026

A Novel Homozygous Mutation in ARL2BP Causes Multiple Morphological Abnormalities of the Flagella and Primary Ciliary Dyskinesia.

Primary ciliary dyskinesia (PCD) and multiple morphological abnormalities of the sperm flagella (MMAF) frequently co-occur in male infertility. However, the genetic basis of this syndromic presentation remains unclear. Using whole-exome sequencing, we identified a novel homozygous ARL2BP splice-site mutation (c.294-2A>G) in a 23-year-old infertile male from a consanguineous family who presented with syndromic PCD and MMAF. This variant causes aberrant pre-mRNA splicing and triggers nonsense-mediated mRNA decay, resulting in the complete absence of ARL2BP protein expression. Transmission electron microscopy revealed extensive disorganization of flagellar axonemes with consistent central pair (CP) microtubule depletion and disorganization of peripheral doublets. Immunofluorescence confirmed a severe deficiency of the CP protein SPAG6 in the sperm flagella. Notably, the patient presented without retinal symptoms. Given that ARL2BP-related retinitis pigmentosa generally emerges during the third decade, long-term ophthalmological follow-up is essential to detect delayed-onset retinal degeneration. In conclusion, these findings confirm ARL2BP as a causative gene for both PCD and MMAF, expanding the genotypic and phenotypic spectrum of ciliopathies.

Humans↗
PubMed2026

De Novo TRIO Missense Variants Disrupt Ras-GEF Domains and Cause Congenital Ventriculomegaly and Hydrocephalus.

Congenital hydrocephalus (CH), characterized by congenital ventriculomegaly (CV), affects approximately 0.5-1 per 1000 live births and is a common cause of pediatric neurosurgical intervention, yet its genetic architecture remains incompletely defined. We report a child with syndromic CH requiring cerebrospinal fluid diversion who harbored a pathogenic de novo missense variant in TRIO (c.3232C > T; p.(Arg1078Trp)), a gene previously associated with autosomal dominant neurodevelopmental disorders featuring variable head circumference. This case prompted systematic evaluation of TRIO variation in our CV/CH cohort (2,697 patient-parent trios) using exome sequencing. We identified five additional unrelated probands with de novo TRIO variants, including two novel substitutions affecting the same residue within the Ras-GEF1 domain (p.(Glu1299Lys) and p.(Glu1299Gly)), yielding significant gene-level enrichment for protein-damaging de novo variants (adjusted p = 6.12 × 10-5). All affected individuals exhibited CV, frequently accompanied by developmental delay and additional structural brain abnormalities. In silico structural modeling predicted that associated variants destabilize critical TRIO Ras-GEF domains required for Rho GTPase activation. Analysis of single-nucleus transcriptomic data from the developing human neocortex revealed enrichment of TRIO expression in multipotent progenitor populations. A systematic literature review identified six additional individuals with TRIO de novo variants and reported CV or CH, including an unrelated patient with the same p.(Arg1078Trp) substitution. Together, these findings expand the phenotypic spectrum associated with pathogenic TRIO variation to include CV/CH and support TRIO as a clinically relevant gene in the genetic evaluation of syndromic CV/CH patients.

Humans↗
PubMed2026

The Landscape of Genomic and Socioeconomic Variables in Patients with Colorectal Cancer Based on Genetic Ancestry.

BACKGROUND: Despite differences in tumor alterations across genetic ancestries, investigations of the colorectal cancer molecular landscape have used self-reported ethnicity instead of genetic ancestry. METHODS: We used tumor and matched normal whole-exome sequencing data from 16,388 patients with stage I to IV colorectal cancer to investigate colorectal cancer's germline and somatic molecular landscape and the potential influence of socioeconomic factors (Distressed Communities Index, DCI) across diverse genetic ancestries. Genetic ancestry determined via supervised local ancestry inference included African (AFR, N = 1,697), Native American (AMR, N = 1,291), East Asian (EAS, N = 2,247), European (EUR, N = 9,726), Levantine Middle Eastern (LME, N = 1,192), and South Asian (SAS, N = 184). RESULTS: Microsatellite instability (MSI) was the most common form of hypermutation (80.8%), higher in the EUR genetic ancestry than in the AFR, AMR, and EAS genetic ancestry. Among germline findings, positive results were most common in high-penetrance genes associated with Lynch syndrome. Enrichment patterns included MLH1 (SAS) and PMS2 (AFR). There were significant differences in the frequency of driver mutations in APC, BRAF, KRAS, TP53, and PIK3CA between the EUR and other ancestry groups in both MSI and microsatellite stable tumors. Mutational signatures suggested enrichment of reactive oxygen species and POLE in AFR, colibactin in EAS, and aflatoxin and NTHL1 in SAS. DCI scores differed by ancestry (higher distress in AFR/AMR than in EUR), but driver mutation frequencies did not vary across DCI quintiles. CONCLUSIONS: Genetic ancestry shapes hereditary risk, tumor biology, and environmental exposures. IMPACT: These findings suggest that incorporating ancestry into screening, trials, and precision oncology may improve equity, though outcome-linked prospective studies and implementation research are warranted.

Aged↗
PubMed2026

Molecular and Immune Landscape of Recurrent and/or Distant Metastatic Squamous Cell Carcinoma of the Head and Neck: An EORTC/IMMUCAN Project.

PURPOSE: Recurrent and/or metastatic (R/M) squamous cell carcinoma of the head and neck (SCCHN) is a heterogeneous clinical entity with a poor prognosis. The molecular and immune landscape of R/M SCCHN is underexplored. To offer a comprehensive view of the tumor microenvironment and molecular profile of R/M SCCHN, we performed an in-depth molecular and immune characterization, evaluating the impact of human papillomavirus (HPV) status, tobacco and alcohol history, primary tumor site, relapse pattern, and treatment history at the genomic, transcriptomic, and immune levels. EXPERIMENTAL DESIGN: We analyzed 253 R/M SCCHN fresh tumor biopsies from the IMMUcan project using RNA sequencing (RNA-seq), whole-exome sequencing, and multiplex immunofluorescence (mIF). RESULTS: The primary clinical factor affecting the immune microenvironment was the number of treatment lines, with significant declines in T cells and B cells observed via mIF and RNA-seq as the number of R/M treatment lines progressed. IL6, IL13, IL15, and NRF2 pathways were enriched in HPV-negative R/M SCCHN compared with HPV-positive tumors, whereas no immune differences were detected between these two clinical groups. Specific genomic alterations were observed in laryngeal cancer (DDR2, FOXP1, KLF5, and ROBO2), whereas nonsmokers/nondrinkers exhibited alterations in SPEN, PBRM1, and CYLD. 11q13.3 amplification was linked to HPV-negative metastatic tumors and hypopharyngeal cancer. HPV-negative SCCHN with locoregional recurrence showed elevated EGFR and CXCL12 pathway activity. Partial epithelial-mesenchymal transition transcriptomic signatures correlated with poor survival, whereas lymphocyte infiltration, especially in the context of tertiary lymphoid structures, was associated with improved survival. CONCLUSIONS: Our study highlights key molecular and immune differences across R/M SCCHN subgroups, identifies potential biomarkers, and suggests biological rationales for tailored therapeutic strategies.

Humans↗
PubMed2025

Double Genetic Diagnosis Involving MECP2 and EPHB4 in a Child with Neurodevelopmental Delay and Vascular Anomalies: A Case Report.

BACKGROUND: Double genetic diagnoses are increasingly identified with the advent of genome-wide sequencing techniques. While MECP2 mutations are associated with Rett syndrome and EPHB4 mutations with vascular malformation syndromes, their co-occurrence has not been previously described. CASE PRESENTATION: We describe an 8-year-and-2-month-old girl presenting with global developmental delay, autism spectrum disorder, and stereotypic behaviors, along with multiple well-demarcated cutaneous vascular lesions. Although she had no clinical seizures, electroencephalogram revealed epileptiform discharges. Physical examination showed dysmorphic features and vascular anomalies, including telangiectatic pink-to-red macular vascular lesions. Whole exome sequencing (WES) identified two de novo heterozygous pathogenic variants: a missense mutation in MECP2 (c.433C>T; p.Arg145Cys), a gene classically implicated in Rett syndrome, and a nonsense mutation in EPHB4 (c.1093C>T; p.Arg365Ter), which has been previously associated with capillary malformation-arteriovenous malformation syndrome type 2. The neurodevelopmental findings, while consistent with the broader spectrum of MECP2-related disorders, along with coexisting vascular anomalies, were best accounted for by a dual genetic diagnosis involving both MECP2 and EPHB4. CONCLUSION: This case underscores the diagnostic value of considering dual genetic diagnoses in patients with complex phenotypes and highlights the role of WES in uncovering multilocus variation, thereby expanding the known phenotypic spectrum associated with MECP2 and EPHB4 mutations.

Double genetic diagnosis↗
PubMed2026

Integrating Optical Genome Mapping into the Genetic Diagnostic Algorithm: Clinical Utility in Unresolved Autosomal Recessive Disorders from a Large Cohort.

INTRODUCTION: The identification of precise genetic etiologies is indispensable for the clinical management of monogenic disorders. However, conventional diagnostic methods and exome sequencing (ES) frequently fail to identify complex structural variations (SVs), leaving the genetic basis unexplained in approximately 30-60% of suspected cases. Optical genome mapping (OGM) emerges as a high-resolution technology capable of detecting cryptic SVs inaccessible to standard methodologies. METHODS: In this study, we evaluated the clinical utility of integrating OGM into the diagnostic algorithm for unresolved monogenic diseases. Following negative or inconclusive results from standard ES pipelines, OGM was applied to a targeted subset of patients (n = 7) selected from a comprehensive clinical cohort of 1,257 individuals with suspected genetic disorders. RESULTS: The integration of OGM identified candidate SVs that may represent the second allelic alteration in two distinct cases; however, confirmation through parental segregation analysis remains pending. Specifically, OGM identified an intronic insertion in the TTLL5 gene and a deletion in a putative regulatory region approximately 400 kb upstream of the NMNAT1 gene, both of which were missed by prior diagnostic testing. CONCLUSION: Our findings suggest that OGM has potential value in investigating the missing heritability of autosomal recessive disorders. By detecting candidate SVs invisible to conventional methods, OGM may warrant consideration as a complementary diagnostic approach following inconclusive ES; however, larger cohorts and confirmatory functional studies are needed to establish its clinical utility.

Autosomal recessive disorders↗
PubMed2026

Somatic mutations reveal hyperactive Notch signaling in prurigo nodularis.

Prurigo nodularis (PN) is a chronic inflammatory skin disease characterized by pruritic skin nodules of unknown etiology. Little is known about genetic changes in PN pathogenesis, particularly somatic events, which are often implicated in inflammatory conditions. We thus performed whole-exome sequencing on 54 lesional and nonlesional skin biopsies from 17 patients with PN and 10 patients with atopic dermatitis (AD) for comparison. Somatic mutational analysis revealed that PN lesional skin harbors recurrent somatic mutations in fibrotic, neurotropic, and cancer-associated genes that are absent in adjacent PN nonlesional skin. Nonsynonymous mutations were most frequently present in NOTCH1 and the Notch signaling pathway, a key regulator of cellular proliferation and tissue fibrosis. In contrast, NOTCH1 mutations were absent in AD. Somatic copy-number analysis, combined with expression data, identified recurrently deleted and downregulated genes in PN lesional skin, which are associated with axonal guidance and extension. Follow-up immunofluorescence validation demonstrated increased NOTCH1 expression in PN lesional skin fibroblasts and increased Notch signaling in PN lesional dermis. Finally, a multicenter analysis revealed increased risk of NOTCH1-associated diseases in patients with PN. In characterizing the somatic landscape of PN, this study highlights the potential role of Notch pathway dysregulation in PN pathogenesis and fibrosis.

Humans↗
PubMed2026

Comparative analysis of distinct genomic landscapes in young-onset gBRCA1/2 breast cancer.

Carriers of germline BRCA1/2 pathogenic variants (gBRCA1/2 PVs) have elevated young-onset breast cancer risk. To define the pretreatment genomic landscapes of young-onset gBRCA-associated breast cancer, we evaluated 136 treatment-naive tumors diagnosed before age 50 in the prospective POSH study and 66 noncarriers from The Cancer Genome Atlas. Using whole-exome sequencing, we analyzed somatic variation, allele-specific loss of heterozygosity (asLOH), homologous recombination deficiency (HRD), and single-base substitution (SBS) signatures. gBRCA1 and gBRCA2 breast cancers had high rates of asLOH but differed significantly in average HRD scores and median SBS composition of signatures SBS1 (aging-associated), SBS18 (ROS-associated), and SBS3 (HRD-associated). Compared with gBRCA2 tumors, gBRCA1 tumors with asLOH were significantly enriched for alterations in hallmark ROS, DNA repair, and epithelial-mesenchymal transition pathways. In ER-positive, HER2-negative tumors from gBRCA1/2 carriers compared with noncarriers, we found significant enrichment of RB1, TP53, FAT1, and MYC single-nucleotide variants, indels, and copy number variants associated with CDK4/6 inhibitor (CDK4/6i) resistance. Together, these findings demonstrate significant differences between gBRCA1- and gBRCA2-associated breast cancers, and preexisting CDK4/6i resistance mechanisms, supporting prospective trials comparing individualized therapy for gBRCA1 versus gBRCA2 carriers and comparing poly(ADP-ribose) polymerase inhibitors versus CDK4/6i for ER-positive gBRCA1/2-associated breast cancer.

Humans↗
PubMed2025

Novel genetic determinants contribute to hearing loss in a central European cohort with enlarged vestibular aqueduct.

BACKGROUND: The enlarged vestibular aqueduct (EVA) is the most commonly detected inner ear malformation. Biallelic pathogenic variants in the SLC26A4 gene, coding for the anion exchanger pendrin, are frequently involved in determining Pendred syndrome and nonsyndromic autosomal recessive hearing loss DFNB4 in EVA patients. In Caucasian cohorts, the genetic determinants of EVA remain unknown in approximately 50% of cases. We have recruited a cohort of 32 Austrian patients with hearing loss and EVA to define the prevalence and type of pathogenic sequence alterations in SLC26A4 and discover novel EVA-associated genes. METHODS: Sanger sequencing, single nucleotide polymorphism (SNP) assays, copy number variation (CNV) testing, and Exome Sequencing (ES) were employed for gene analysis. Cell-based functional and molecular assays were used to discriminate between gene variants with and without impact on protein function. RESULTS: SLC26A4 biallelic variants were detected in 5/32 patients (16%) and monoallelic variants in 5/32 patients (16%). The pathogenicity of the uncharacterized SLC26A4 protein variants was assigned or excluded based on their ion transport function and cellular abundance. The monoallelic or biallelic Caucasian EVA haplotype was detected in 7/32 (22%) patients, but its pathogenicity could not be confirmed. X-linked pathogenic variants in POU3F4 (2/32, 6%) and biallelic pathogenic variants in GJB2 (2/32, 6%) were also found. No CNV of SLC26A4 and STRC genes was detected. ES of eleven undiagnosed patients with bilateral EVA detected rare sequence variants in six EVA-unrelated genes (monoallelic variants in SCD5, REST, EDNRB, TJP2, TMC1, and two variants in CDH23) in five patients (5/11, 45%). Cell-based assays showed that the TJP2 variant leads to a mislocalized protein product forming dimers with the wild-type, supporting autosomal dominant pathogenicity. The genetic causes of hearing loss and EVA remained unidentified in (14/32) 44% of patients. CONCLUSIONS: The present investigation confirms the role of SLC26A4 in determining hearing loss with EVA, identifies novel genes in this pathophysiological context, highlights the importance of functional testing to exclude or assign pathogenicity of a given gene variant, proposes a possible diagnostic workflow, suggests a novel pathomechanism of disease for TJP2, and highlights voids of knowledge that deserve further investigation.

Humans↗