Search Results (397)

The flavivirus NS1 protein is a component of the viral replication complex and plays diverse, yet poorly understood, roles in the viral life cycle. To enable real-time visualization of the developing replication organelle and biochemical analysis of tagged NS1 and its interacting partners, we engineered a replication-competent yellow fever virus (YFV) replicon encoding a C-terminal fusion of NS1 with green fluorescent protein (NS1–GFP). The initial variant was non-viable in the absence of trans-complementation with wild-type NS1; however, viability was partially restored through the introduction of co-adaptive mutations in GFP (Q204R/A206V) and NS4A (M108L). Subsequent cell culture adaptation generated a 17-nucleotide frameshift within the NS1–GFP linker, resulting in a more flexible and less hydrophobic linker sequence. The optimized genome, in the form of a replicon, replicates in packaging cells that produce YFV structural proteins, as well as in naive BHK-21 cells. In the packaging cells, the adapted NS1–GFP replicon produces titers of infectious particles of approximately 10^6 FFU/mL and is genetically stable over five passages. The expressed NS1–GFP fusion protein localizes to the endoplasmic reticulum and co-fractionates with detergent-resistant heavy membranes, a hallmark of flavivirus replication organelles. This NS1–GFP replicon provides a novel platform for studying NS1 functions and can be further adapted for proximity-labeling strategies aimed at identifying the still-unknown protease responsible for NS1–NS2A cleavage. Full article

The neurofibromin 1 (NF1) splice-site mutation c.61-2A>G (rs1131691100) is a rare, pathogenic, autosomal dominant variant that disrupts NF1 tumor-suppressor function, causing neurofibromatosis type 1 (NF1). Its pathogenic mechanism is poorly understood, and the potential for personalized therapeutic genome editing remains unknown due to the absence of a standard framework for investigating splicing disorders. Here, we performed a comprehensive multi-omics analysis of a de novo c.61-2A>G case from South Korea, integrating short- and long-read whole genome sequencing, whole transcriptome sequencing, and methylation profiling. We confirm that c.61-2A>G abolishes the canonical splice acceptor site, activating a cryptic splice acceptor 16 nucleotides downstream in exon 2. This splicing shift generates a 16-nucleotide deletion, causing a frameshift and premature stop codon that truncates the protein’s N-terminal region. Long-read sequencing further reveals that the mutation creates a novel CpG dinucleotide, which is methylated in the majority of reads. Finally, we assessed therapeutic correction strategies, revealing that CRISPR-Cas9 prime editing is the only viable approach for in vivo correction. This study provides the first comprehensive multi-omics characterization of the NF1 c.61-2A>G mutation and establishes a minimal framework for precision therapeutic development in silico in monogenic splicing disorders. Full article

Non-small cell lung cancer (NSCLC) accounts for approximately 85% of lung cancers with adenocarcinoma being the most common subtype. Patients with stage IV NSCLC typically have poor prognosis. In these patients, identification of actionable genomic alterations allows for the selection of targeted therapy rather than chemotherapy or chemo-immunotherapy. EGFR mutations are a common oncogenic driver in NSCLC and are targetable by tyrosine kinase inhibitors (TKIs). However, most of the studies primarily focus on common mutations, which are exon 19 deletions (Ex19del) and exon 21 (L858R) point mutations, and there is inconsistent data on efficacy in the treatment of patients with uncommon EGFR mutations. Currently, the first-line treatment for patients with common EGFR mutations involves a third-generation TKI, typically osimertinib. This case describes a 66-year-old gentleman with two uncommon EGFR frameshift deletions (E701fs and L702fs). His tumor staging was denoted as cT3N2M1b, stage IVA. The patient demonstrated a radiological and biochemical response to osimertinib as part of the OCELOT clinical trial (supported by a grant from AstraZeneca), with evidence of tumor marker decline and radiographic improvement within two months of osimertinib treatment initiation. This response has been durable with continued radiological stability and biochemical improvement at 11 months and ongoing. This case will help guide management for patients with this uncommon EGFR mutations and contribute to the scarce literature of EGFR frameshift deletions in advanced NSCLC patients. Full article

Background/Objectives: Advances in the genetic understanding of pheochromocytoma–paraganglioma (PPGL) have considerably refined personalized approaches to diagnosis and management. This study aims to present our institutional experience on the diagnostic characteristics, clinical course, and genetic background of patients with PPGL, in the context of the current literature. Methods: This retrospective analysis included 35 patients diagnosed with PPGL between years 2020 and 2024, all of whom underwent surgical resection and next-generation sequencing for germline mutations in major PPGL susceptibility genes. Clinical presentation, biochemical profile, pathological findings, and follow-up outcomes were compared between mutation-positive and mutation-negative cases. Results: Of the 35 patients with PPGL, germline mutations were identified in 6 patients (17%): 2 in Cluster 1A genes (SDHA, SDHB), 2 in Cluster 1B (VHL), and 2 in Cluster 2 (NF1). Consistent with existing literature, pathogenic germline variants—particularly SDHB and VHL—were identified in our cohort exclusively in patients younger than 30 years (ages 17, 20, and 25). Mutation-positive patients more frequently exhibited noradrenergic or non-secretory profiles (p = 0.01). Among the three non-secretory tumors in the cohort, two harbored genetic mutations (SDHA, NF1). Interestingly, both NF1-positive patients were normotensive—one (c.3496G > A) with a non-secretory tumor and the other (c.2329T > A) presenting at an unusually late age (63 years)—a strikingly atypical spectrum that underscores the phenotypic variability of NF1-associated PPGL. Bilateral disease was observed exclusively in VHL carriers (p = 0.03). Importantly, we identified a rare VHL c.369delG frameshift variant, not previously reported in association with PPGLs, in a patient with PPGL. No significant difference was observed between SDHB loss (p = 0.1) and proliferative indices (mitotic count, Ki-67) (p = 0.07, p = 0.6) between the two groups. During a median follow-up of 24 months (IQR: 18–36), one SDHB-positive patient had a recurrence, while no distant metastases were detected in the remaining mutation carriers. Conclusions: These findings support characteristic clinical patterns among mutation-positive PPGL and underscore the importance of systematic germline testing in all cases—irrespective of age, family history, or biochemical profile—to guide individualized management and enable cascade screening. The identification of a rare VHL c.369delG variant, previously unreported in association with PPGL, within a characteristic VHL-related clinical phenotype highlights the importance of this association. Similarly, atypical NF1 cases emphasize phenotypic variability and reinforce the importance of germline testing even in clinically silent presentations. Full article

Genome editing of late myogenic regulators provides a way to dissect the mechanisms through which transcriptional programs and growth-related signaling pathways shape muscle gene expression programs in farmed fish. This study disrupted myogenic regulatory factor 4 (MRF4) in Nile tilapia using CRISPR/Cas9 to examine downstream transcriptional changes in fast skeletal muscle across the trunk, belly, and head regions. Adult F0 crispants carried a frameshift mutation that truncated the basic helix–loop–helix domain and showed an approximate 80–85% reduction in MRF4 mRNA across the trunk, belly, and head muscles. The expression of 23 genes representing myogenic regulatory factors, MEF2 paralogs, structural and contractile components, non-myotomal regulators, cell adhesion and fusion-related transcripts, and growth-related genes within the GH–IGF–MSTN axis was quantified and compared between wild-type and MRF4-crispants. Expressions of major structural genes remained unchanged despite MRF4 depletion, whereas MyoG and MyoD were upregulated together with MEF2B and MEF2D, indicating strong transcriptional compensation. Twist1, ID1, PLAU, CDH15, CHRNG, NCAM1, MYMK, GHR, and FGF6 were also significantly elevated, while IGF1 was reduced, and MSTN remained stable. Together, these results show that MRF4 loss is associated with coordinated transcriptional changes in regulatory and growth-related pathways, while major fast-muscle structural and contractile transcript levels remain stable, thereby highlighting candidate transcriptional targets for future studies that will evaluate links to muscle phenotype and growth performance in Nile tilapia. Full article

Background: Advances in genomic technologies combined with tandem mass newborn screening have enabled early detection and management of several common inborn errors of metabolism. Fructose-1,6-bisphosphatase deficiency, an autosomal recessive treatable disorder reported in around 150 patients worldwide, remains underdiagnosed despite an excellent prognosis with early detection. Although common in highly consanguineous populations, diagnosis is often delayed due to the non-specific clinical and biochemical profile. Methods: This report explores the diagnostic pathway using first-tier next-generation sequencing of three novel cases of fructose-1,6-bisphosphatase deficiency in a tertiary care center in Lebanon. Results: Two patients were diagnosed with first-tier exome sequencing within one month of presentation and had an excellent outcome at 6 years of follow-up. The third patient, undiagnosed for 10 years, suffered from neurological sequalae. The molecular profile was remarkable in two patients for exon 2 deletion in the FBP1 gene, a founder mutation reported in Turkish and Armenian patients, and a rare frameshift mutation in the third case. Conclusions: The use of next-generation sequencing as as a first-tier test for FBP deficiency is a non-invasive and rapid method for early diagnosis and management of this rare yet treatable disorder. It can detect both disease-causing variants and large deletions, founder mutations as well, delineating the molecular profile in populations where this disorder is highly prevalent. Full article

Monogenic forms of severe early-onset obesity often involve genetic disruptions in the hypothalamic leptin-melanocortin pathway. Pathogenic variants in the SIM1 gene, a key transcription factor required for the development of the paraventricular nucleus, are a known cause of Prader–Willi-like syndrome, characterized by hyperphagia, severe obesity, and developmental delay. We performed targeted next-generation sequencing of 52 obesity-associated genes on a cohort of pediatric patients with severe early-onset obesity. Identified variants were analyzed for population frequency and predicted pathogenicity using in silico tools. The structural impact of the novel missense variants was assessed using protein domain modeling with AlphaFold3. We identified five rare SIM1 variants in eleven patients. Four were heterozygous nonsynonymous variants: one frameshift in the bHLH domain (p.Ser18Ter), one frameshift in the Per-ARNT-Sim domain (p.His143Ter), and two missense variants, p.Pro30Ala and p.Ser663Leu. Structural modeling suggested that the missense variants are likely to disrupt critical protein–protein interactions. The fifth variant was a synonymous change, c.1173G>A, p.(Ser391Ser), which was detected in five unrelated patients. Bioinformatic analysis predicted that this variant could alter splicing. Structural modeling suggested that the missense variants interfere with SIM1 function. This study expands the mutational spectrum of SIM1-linked monogenic obesity, reporting novel likely pathogenic frameshift variants, a missense variant, and a recurrent synonymous variant with a potential splice-site effect. The majority of the variants are predicted to affect the SIM1 protein. Our findings strengthen the critical role of the SIM1 gene in hypothalamic development and energy homeostasis. The results underscore the importance of including the SIM1 gene in genetic testing panels for children with severe obesity and hyperphagia, enabling precise diagnosis and potential future personalized management. Functional in vitro or in vivo validation of these variants is required to confirm their pathogenicity. Full article

Despite years of study, the biological role of the human proinsulin connecting peptide (C-peptide) remains poorly understood. Nevertheless, the C-peptide exhibits subdomains including conserved residues that are thought to have co-evolved with the insulin moiety of proinsulin. Genome-wide association studies in humans suggest that alterations of glycemic control may exhibit a possible linkage with the presence of certain C-peptide variants other than frame-shifts, stop codons, alternative splice variants, or the addition of an extra unpaired Cys residue. Although the C-peptide is ultimately excised from insulin, here, we have bioengineered missense mutations in the amino-terminal portion of the C-peptide (especially involving or near preproinsulin residues Q62,V63) that we find impair proinsulin folding and trafficking efficiency and, in this way, impair insulin biogenesis. We show that proinsulin bearing a C-peptide missense variant can also physically interact with co-expressed wildtype proinsulin, affecting the trafficking behavior of both proinsulin proteins in a manner that is directly related to the relative expression ratio of the variant and wildtype gene products. We conclude that in addition to other possible functions, the amino-terminal portion of the C-peptide influences proinsulin folding and trafficking and, in this way, affects human insulin production. Full article

Insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) is an RNA-binding protein known to play critical roles in metabolism, cell proliferation, and tumorigenesis. Although its involvement in muscle development has been documented in several species, the function of goose IGF2BP2 remains largely unexplored. In this study, we cloned and characterized the full-length cDNA and genomic DNA sequences of goose IGF2BP2. The cDNA is 2957 bp in length and contains a 1662 bp open reading frame encoding a 553-amino acid protein with five conserved RNA-binding domains. The genomic sequence spans 12,183 bp and consists of 12 exons and 11 introns. A total of 60 genetic variants were identified, including a deletion of a G base at position 2299 (g.2299delG) that results in a frameshift mutation. Expression analysis revealed high levels of IGF2BP2 mRNA in the liver, heart, and muscle tissues of female geese across embryonic (E25d), growing (A70d), and laying (L270d) stages, consistent with a potential role in muscle development (p < 0.05). Functionally, overexpression of IGF2BP2 in skeletal muscle satellite cells (SMSCs) was associated with significant changes in the expression of several genes linked to muscle development and signaling pathways, including upregulation of IGF1, EGFR, FGF19, BMP6, BMP2, ACVR1C and WNT5A and downregulation of MYBPC3, NODAL, HOXD13, TNXB, and ADD2 (Padj < 0.01). Furthermore, protein–protein interaction (PPI) network analysis of these genes suggests that IGF2BP2 may coordinate key genes, contributing to its potential role in skeletal muscle development in geese. Full article

Nodal marginal zone lymphoma (NMZL) is an indolent B-cell lymphoma that may pose diagnostic challenges due to the absence of distinct markers. In rare atypical cases, an overabundance of PD1+ T follicular helper (TFH) cells in tumor tissue may mimic peripheral T-cell lymphoma (PTCL) of TFH origin, further complicating the diagnosis. A 72-year-old woman with progressive lymphadenopathy had a cervical lymph node biopsy showing a disrupted architecture with monomorphic nodules of CD20+/MNDA+ B-cells and a prominent central population of proliferating CD4+/PD1+ T-cells, initially suggestive of a PTCL-TFH. The bone marrow contained aggregates of CD20+ B-cells intermixed with CD3+/CD4+/PD1+ T-cells. Next-generation sequencing (NGS) revealed clonal immunoglobulin heavy-chain rearrangements in the lymph node and bone marrow, with T-cell receptor genes displaying a polyclonal pattern. Targeted NGS showed no PTCL-related alterations but identified NMZL-associated mutations with different distributions across lymph node and bone marrow compartments. NOTCH2 mutations (c.6418C>T; p.Gln2140*) were found in both tissues, while the (c.69+2T>A; p.?) TNFRSF14 gene mutation was only detected in the lymph node. The KMT2D gene displayed a frameshift variant in the lymph node (c.4801_4802delinsT; p.Arg1601Leufs*3) and an in-frame deletion (c.11756_11758del; p.Gln3919del) in the bone marrow. Notably, NGS and digital droplet PCR confirmed a TP53 frameshift mutation (c.902del; p.Pro301Glnfs*44) with a fractional abundance of 0.31% in the lymph node and a (c.742C>T; p.Arg248Trp) mutation (0.309%) in the bone marrow. Results underscore the importance of NGS-based clonality to diagnose NMZL with prominent PD1+ T-cell hyperplasia, and prompt further investigation into tissue-specific mutational signatures in these unusual cases. Full article

Activation through the T cell receptor (TCR) initiates a signaling cascade in T cells that induces extensive molecular and cellular changes. The adaptor protein Linker for Activation of T cells (LAT) plays an essential role in transducing activation and regulatory signals downstream of the TCR. Phosphorylation of LAT tyrosine residues recruits multiple signaling proteins, leading to the assembly of the LAT signalosome, which is crucial for relaying signals that regulate T cell development and function. We previously showed that substitution of a negatively charged amino acid segment preceding the fifth tyrosine residue of LAT (Tyr127 in humans or Tyr132 in mouse LAT) enhances some early TCR signaling events, whereas downstream responses, such as Ca²⁺ influx and Erk phosphorylation, are partially inhibited. To investigate the physiological relevance of this segment in vivo, we generated a new LAT knock-in mouse strain (Lat^NIL) in which the negatively charged segment was replaced with a non-charged sequence. Unexpectedly, this mutation led to an alternative splicing event in the Lat gene that excluded exons 6 and 7, resulting in a frameshift, a premature stop codon at residue 145, and the loss of the six C-terminal tyrosine residues of LAT. Homozygous Lat^NIL/NIL mice showed a phenotype similar to that of LAT-knockout and Lat^4YF mice (in which the four C-terminal tyrosines had been mutated to phenylalanine). Interestingly, homozygous Lat^NIL/NIL mice exhibited a distinct population of γδ T cells in lymphoid organs, which has not been observed in LAT-KO or Lat^4YF mice. These γδ T cells expressed higher levels of CD27 compared to those in wild-type and LAT-KO mice, suggesting altered activation or differentiation states. Together, these data highlight how subtle alterations in LAT structure can profoundly impact T cell signaling and lineage composition. Full article

Purpose: ATRIP (ATR-interacting protein) is a critical partner of ATR (ataxia telangiectasia and Rad3-related). The ATR-ATRIP heterodimer plays an essential role in initiating homologous recombination repair (HRR) during replication stress and inducing double-stranded DNA breaks following unresolved stalled replication forks. Our team recently identified ATRIP as a novel breast cancer susceptibility gene candidate through whole-exome sequencing (WES) of familial breast cancer patients and healthy controls from the Polish founder population, with subsequent validation in both Polish and British cohorts. In the present study, we report for the first time the detection of a novel deleterious mutation in ATRIP among several members of an Iranian family with clustering of breast cancer who were negative for mutations in the already known breast cancer risk genes. Methods: Six family members underwent germline DNA testing by WES, following initial negative results from multigene panel testing. Candidate variants were confirmed by Sanger sequencing and assessed according to ACMG guidelines. Results: We detected a novel ATRIP frameshift mutation (NM_130384.3:c.1033delC) in four of six family members that were tested, including two individuals affected with breast cancer. No pathogenic variants were found in other known cancer susceptibility genes. Conclusions: This is the first report of a deleterious ATRIP mutation in an Iranian family with familial breast cancer, suggesting a potential role of ATRIP in hereditary breast cancer. Further studies are required to confirm the role of ATRIP in breast cancer susceptibility, refine risk assessment, and evaluate potential personalized therapeutic strategies. In the interim, genetic counseling for ATRIP mutation carriers should proceed with caution, given current limitations in clinical interpretation. Full article

This study investigates FLNC mutations in Chinese cardiomyopathy patients. Background: Inherited cardiomyopathies, including dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), restrictive cardiomyopathy (RCM), and arrhythmogenic right ventricular cardiomyopathy (ARVC) are major heart failure causes. FLNC, critical for muscle structure, is implicated in myofibrillar myopathy and isolated DCM (3–4% cases) with ventricular arrhythmias. Missense variants are linked to HCM and protein aggregation. A cohort of 25 patients with pathogenic/likely pathogenic FLNC mutations (2022–2025, Beijing Anzhen Hospital) underwent whole-exome sequencing (WES) using IDT kit 1.0/Hiseq 4000. Variants were classified via the American College of Medical Genetics and Genomics (ACMG) guidelines. Clinical data (echocardiography, CMR, labs) and follow-up data (prognosis, meds, and family history) were collected. The statistics used SPSS (p < 0.05). The mean age was 38 ± 14.6 years (13 males). There were 25 FLNC mutations: 12 single nucleotide polymorphisms (SNPs), 5 deletions, 2 duplications, and 3 deletion-insertions, classified as 6 pathogenic, 16 likely pathogenic, and 3 variants of uncertain significance (VUS). Diagnoses: 24% dilated cardiomyopathy (DCM), 8% hypertrophic cardiomyopathy (HCM), and 4% left ventricular non-compaction. Nonsense mutation carriers exhibited significantly higher tricuspid regurgitation prevalence compared to frameshift mutation carriers (6/9 vs. 2/10; p = 0.04). Echocardiography revealed reduced left ventricular ejection fraction (LVEF) (41.5 ± 14.1%), with statistically significant differences in fractional shortening (p = 0.024) and aortic root diameter (p = 0.028). Pedigree analysis confirmed that a frameshift mutation (LP) co-segregated with familial DCM and was associated with severe phenotypes, including sudden cardiac death. Furthermore, nonsense FLNC mutations correlated with increased tricuspid regurgitation severity, smaller aortic root dimensions, and reduced pulmonary artery flow velocity. Full article

Introduction: Autoimmune encephalitis (AE) is a neurological disorder caused by immune responses targeting neuron-surface or synaptic proteins. While its immunological mechanisms have been studied, the genetic underpinnings remain unclear. This study investigates whether rare deleterious variants (RDVs) in immunological genes contribute to AE susceptibility. Method: We enrolled 36 patients with AE and 407 healthy controls without autoimmune diseases. Whole-exome sequencing was performed to identify RDVs, including start-loss, stop-gain, frameshift, splice-site variants, and deleterious missense mutations. We analyzed the distribution of RDVs in an immunological gene set and its subsets. A burden test was used to identify genes significantly associated with AE. Results: Overall, RDVs in the full immunological gene set did not differ between AE patients and controls. However, the T cell receptor signaling pathway subset showed a significantly higher RDV burden in AE patients. Within this pathway, PDK1 was significantly associated with AE. Two additional genes, CAT and MIA, also showed strong associations, although their broader gene subset, cytokines, did not display differential RDV distribution. Discussion: Our findings suggest that RDVs in specific immunological pathways, particularly the T cell receptor signaling pathway, may play a role in AE pathogenesis. The significant associations of PDK1, CAT, and MIA with AE highlight potential genetic contributors to the disease. Further functional studies are necessary to validate these associations and explore their biological relevance, potentially paving the way for improved understanding and future therapeutic targets in AE. Full article

The fluorescent dyes 9-aminoacridine (9-AA) and acridine orange (AO) are known mutagens that induce frameshift mutations in cells by intercalating between DNA bases. However, these chemicals can also affect other cellular components, such as proteins. In this study, we tested the ability of 9-AA and AO to induce heat shock in bacteria using the following methods: lux-biosensors based on Escherichia coli cells with the luxCDABE genes transcriptionally fused to heat shock-specific inducible promoters, RT-qPCR, and nanoDSF. We demonstrated that acridine dyes not only induce mutagenesis but also cause heat shock in bacterial cells. AO significantly reduced the melting temperature of proteins and strongly activated σ^E- and σ³²-dependent promoters, but not PluxC, which is activated by elevated temperatures via a different mechanism. In contrast, 9-AA weakly denatured the proteins and induced the σ^E-dependent promoter; however, it activated the σ³²-dependent promoters and PluxC, supporting the hypothesis that the σ³² heat shock response system is activated via hairpin RNA denaturation by 9-AA. The study on the application of lux-biosensors was hampered by the high general toxicity and luminescence shielding effect of AO, and RT-qPCR’s sensitivity was insufficient for detection of the response to 9-AA. Thus, methodologically, it is justified to conduct a comprehensive study of substances that cause heat shock or affect bioluminescence by both RT-qPCR and lux-biosensors. Full article