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Substitutions of nucleotides at the 3' ends of COL6A1/2/3 exons induce exon skipping associated with collagen VI-related muscular dystrophies and therapeutic strategies.

PURPOSE: Collagen VI-related muscular dystrophies, characterized by proximal muscle weakness and joint contractures, are caused by pathogenic variants in the genes, COL6A1 to COL6A3. A monoallelic variant at the last nucleotide of a COL6A1 exon was initially classified as a missense variant but acted as a splicing variant, resulting in exon skipping. Here, we evaluated whether single-nucleotide variants at the 3'-ends of COL6A1 to COL6A3 exons cause aberrant splicing. METHODS: Ten relevant variants were identified in patients from our repository or public databases, and their muscle COL6A1 to COL6A3 transcripts were analyzed. The effects of the variants on splicing were also analyzed by minigene assay and SpliceAI in silico prediction. RESULTS: Transcripts from muscles of individuals with suspected collagen VI-related phenotypes showed exon skipping (skipping rate >12%). Findings of minigene assay and in silico prediction experiments supported these findings. Two therapeutic approaches, splicing correction of pre-messenger RNA or gene silencing of mature messenger RNA were assessed. Among them, gene silencing using short interfering RNAs targeting the skipped transcripts proved to be effective in restoring collagen VI in cells containing the pathogenic variant. CONCLUSION: Single-nucleotide variants at the 3'-ends of exons can lead to aberrant splicing, and allele-specific gene silencing targeting such variants is a promising therapeutic strategy.

Humans

Differential impacts of exon 1-associated and exon 11-associated variants of the rat mu opioid receptor gene, Oprm1, on buprenorphine- and morphine-induced analgesia and respiratory depression in male rats.

Buprenorphine has long been recognized as a mu opioid agonist with a distinctive and intricate pharmacological profile. It is a partial agonist at the mu opioid receptor, an antagonist at the kappa and delta opioid receptors, and an agonist at the nociception opioid receptor. Similar to other mu agonists such as morphine and fentanyl, buprenorphine can produce side effects, including tolerance, physical dependence, respiratory depression, and addiction. The mu opioid receptor gene, OPRM1, undergoes extensive alternative splicing, generating an array of splice variants or isoforms, which are conserved from rodents to humans. These splice variants can be categorized into 2 main types, exon 1 (E1)-associated variants and exon 11 (E11)-associated variants. E1-associated variants primarily consist of full-length, 7-transmembrane C-terminal variants, whereas E11-associated variants are typically truncated 6-transmembrane variants. Previous studies established that buprenorphine analgesia in mice is dependent on both E1- and E11-associated variants. However, the role of these variants in buprenorphine analgesia and respiratory depression in rats remains unclear. In this study, we used CRISPR/Cas9 technology to develop 2 rat Oprm1 gene-targeting models in which E1- and E11-associated variants were selectively disrupted, aiming to investigate their roles in buprenorphine and morphine's actions. The results showed that both E1- and E11-associated variants are essential for buprenorphine's analgesic and respiratory depressional effects in rats, whereas morphine's effects are solely attributed to the E1-associated variants. These findings provide new and important insights into the distinct contributions of the E1- and E11-associated variants to the pharmacological actions of buprenorphine and morphine. SIGNIFICANCE STATEMENT: Differential dependences of buprenorphine and morphine analgesia and respiratory depression on Oprm1 exon 1- and exon 11-associated variants revealed in rat gene-targeting models provide new and important insights into unique contributions of these variants to buprenorphine and morphine actions.

Animals

Rescue of common and rare exon 2 skipping variants of the GAA gene using modified U1 snRNA.

BACKGROUND: Pompe disease (PD) is an autosomal recessive lysosomal storage disorder caused by the deficient activity of acid alpha glucosidase (GAA) enzyme due to mutations in the GAA gene. As a result, undigested glycogen accumulates within lysosomes causing their dysfunction. From a clinical point of view, the disease can be classified in infantile-onset (IO) and late-onset (LO) forms. The common GAA c.-32-13T>G variant, found in 40-70% of LO-PD alleles, is a leaky splicing mutation interfering with the correct GAA exon 2 recognition by the spliceosome leading to the production of non-functional GAA transcripts. In this study, we used modified, GAA-tailored U1 snRNAs to correct the aberrant splicing determined by the c.-32-13T>G and other GAA exon 2-skipping mutations. METHODS: A set of constructs expressing 5 different engineered U1 snRNAs was generated. A functional splicing assay using a GAA hybrid minigene carrying different variants known to affect GAA exon 2 splicing was used to test the effect of engineered U1 snRNAs on exon 2 inclusion. The effect on endogenously expressed GAA transcript and GAA enzymatic activity was assessed by transfecting patient-derived fibroblasts bearing the common c.-32-13T>G with the best performing modified U1 snRNA. RESULTS: Modified U1-3, U1+1 and U1+6 snRNAs were all able to increase, in a dose-dependent manner, the inclusion of exon 2 within the transcript derived from the GAA minigene harbouring the c.-32-13T>G variant. The U1+1 was the most effective one (2,5 fold increase). Moreover, U1+1 snRNA partially rescued the correct splicing of GAA minigenes harbouring mutations that affect the 3'ss (c.-32-3C>G, c.-32-2A>G) and the 5'ss (c.546G>A, c.546G>C, c.546G>T). Notably, the treatment of patient-derived fibroblasts carrying the c.-32-13T>G mutation with the U1+1 snRNA increased the amount of normal GAA mRNA by 1,8 fold and the GAA enzymatic activity by 70%. CONCLUSIONS: we provide the proof-of-concept for the use of modified GAA-tailored U1 snRNAs, designed to potentiate the recognition of the GAA exon 2 5'ss, as therapeutic tools to correct the aberrant transcripts carrying variants that affect exon 2 splicing, including the common c.-32-13T>G variant.

Humans

Rescue of a panel of Hemophilia A-causing 5'ss splicing mutations by unique Exon-specific U1snRNA variants.

BACKGROUND: Aberrant mRNA splicing is a well-established pathogenic mechanism for human disease, but its real impact is hardly predictable and underestimated. Splicing can be therefore modulated for therapeutic purposes, and splicing-switching molecules are in clinics for some diseases. Here, conscious that over 10% of all pathogenic mutations occurs at 5'ss, we aimed at characterizing and rescuing nine 5'ss mutations in three models of defective F8 exons whose skipping would lead to factor VIII (FVIII) deficiency (Hemophilia A), the most frequent coagulation factor disorder. METHODS: HEK293T cells were transfected with F8 minigene variants, alone or with engineered U1 small nuclear RNAs (U1snRNAs), and splicing patterns analysed via RT-PCR. RESULTS: All 5'ss mutations induced exon skipping, and the proportion of correct transcripts, not predictable by computational analysis, was consistent with residual FVIII levels in patients. For each exon we identified a unique engineered U1snRNAs, either compensatory or Exon Specific (ExSpeU1), able to rescue all mutations. Overall, ExSpeU1s were more effective than compensatory U1snRNAs, particularly in the defective exons 6 and 22. CONCLUSIONS: Data highlight the importance of splicing assays to elucidate genotype-phenotype relationships and proved the correction efficacy of ExSpeU1s for each targeted defective F8 exon, thus expanding their translational potential for HA.

Humans

Clinical outcomes and genomic features of uncommon EGFR exon 19 deletion subtypes in osimertinib-treated non-small cell lung cancer.

BACKGROUND: Epidermal growth factor receptor (EGFR) exon 19 deletion subtypes may be associated with differential survival outcomes following EGFR-tyrosine kinase inhibitor treatment. However, evidence remains scarce, particularly regarding osimertinib, and the underlying biological mechanisms are poorly understood. We aimed to compare survival outcomes among EGFR exon 19 deletion subtypes in patients with non-small cell lung cancer (NSCLC) treated with osimertinib. METHODS: In this multicenter retrospective study, patients with NSCLC were stratified according to exon 19 deletion subtypes. Whole-exome sequencing data from the American Association for Cancer Research Genomics Evidence Neoplasia Information Exchange registry and Memorial Sloan Kettering Clinicogenomic Harmonized Oncologic Real-World Dataset were analyzed to investigate co-occurring genomic alterations. RESULTS: Overall, 111 patients with advanced EGFR exon 19 deletion-positive NSCLC were analyzed and 86.5% received osimertinib as first-line therapy. Patients with non-E746_A750del (n&#xa0;=&#xa0;25) had shorter progression-free survival (PFS) than those with E746_A750del (n&#xa0;=&#xa0;86) (median: 14.3 vs. 20.6&#xa0;months; p&#xa0;<&#xa0;0.05). Among non-E746_A750del subtypes, L747_A750delinsP (n&#xa0;=&#xa0;4) had a particularly poor prognosis, with significantly worse survival than those with E746_A750del (median PFS: 3.5 vs. 20.6&#xa0;months; p&#xa0;<&#xa0;0.001, and median overall survival: 11.8 vs. 48.5&#xa0;months; p&#xa0;<&#xa0;0.001). In public database analyses, non-E746_A750del had a higher rate of RBM10 co-mutations, whereas L747_A750delinsP was characterized by frequent CDKN2A/B homozygous deletions and MYC amplifications. CONCLUSIONS: Non-E746_A750del was associated with poorer outcomes, with L747_A750delinsP potentially being a high-risk subtype. Differences in co-occurring genomic alterations may contribute to the prognostic heterogeneity among exon 19 deletion subtypes.

Humans

MET Exon 14 Skipping Mutation in NSCLC: From Genomic Discovery to Biomarker-Guided Therapeutic Innovation.

INTRODUCTION: Non-small cell lung cancer (NSCLC) is the most common type of lung cancer, and the MET exon 14 skipping mutation is a key oncogenic driver, which promotes tumor progression and provides a new direction for precision therapy. METHODS: A systematic search of English-language literature and clinical trial data related to the MET exon 14 skipping mutation from 2020-2025 was performed to summarize the role of the mutation and therapeutic advances. RESULTS: DNA-based next-generation sequencing (NGS), RNA-based NGS, and RT-qPCR were employed as the main detection methods. Preclinical models confirmed that mutations promote tumor progression by activating the RAS/MAPK pathway. Clinical trials have reported objective remission rates (ORR) of 46-68% for first-line treatment with MET inhibitors in NSCLC patients harboring MET exon 14 skipping mutations. DISCUSSION: MET exon 14 skipping mutation as a therapeutic target for NSCLC has made significant progress, and MET inhibitors are more advantageous than chemotherapy and immunotherapy, and have been recommended by national and international guidelines as a first-line treatment option. Additionally, NGS technology has the potential to dynamically monitor tumor evolution and drugresistant mutations, thereby helping to realize precision medicine. CONCLUSION: The MET exon 14 skipping mutation is an important target for the precision treatment of NSCLC, and MET-TKIs have remarkable efficacy but a prominent problem with drug resistance. The construction of a precision medicine system encompassing diagnosis, treatment, and drug resistance management through multi-omics research, technological innovation, and international collaboration is a key direction for improving prognosis.

Humans

Long-term restoration of cardiac dystrophin expression in golden retriever muscular dystrophy following rAAV6-mediated exon skipping.

Although restoration of dystrophin expression via exon skipping in both cardiac and skeletal muscle has been successfully demonstrated in the mdx mouse, restoration of cardiac dystrophin expression in large animal models of Duchenne muscular dystrophy (DMD) has proven to be a challenge. In large animals, investigators have focused on using intravenous injection of antisense oligonucleotides (AO) to mediate exon skipping. In this study, we sought to optimize restoration of cardiac dystrophin expression in the golden retriever muscular dystrophy (GRMD) model using percutaneous transendocardial delivery of recombinant AAV6 (rAAV6) to deliver a modified U7 small nuclear RNA (snRNA) carrying antisense sequence to target the exon splicing enhancers of exons 6 and 8 and correct the disrupted reading frame. We demonstrate restoration of cardiac dystrophin expression at 13 months confirmed by reverse transcription-PCR (RT-PCR) and immunoblot as well as membrane localization by immunohistochemistry. This was accompanied by improved cardiac function as assessed by cardiac magnetic resonance imaging (MRI). Percutaneous transendocardial delivery of rAAV6 expressing a modified U7 exon skipping construct is a safe, effective method for restoration of dystrophin expression and improvement of cardiac function in the GRMD canine and may be easily translatable to human DMD patients.

Alternative Splicing

Enozertinib Is a Selective, Brain-Penetrant EGFR Inhibitor for Treating Non-Small Cell Lung Cancers with EGFR Exon 20 and Atypical Mutations.

UNLABELLED: EGFR mutations are common oncogenic drivers in non-small cell lung cancer (NSCLC), and approximately half of patients develop brain metastases over the course of their disease. Patients with nonclassic EGFR mutations, such as insertions in exon 20, are a high unmet need with a worse prognosis compared with patients with classic EGFR mutations. Here, we describe the discovery and development of enozertinib (formerly ORIC-114), a highly brain-penetrant, orally bioavailable, irreversible inhibitor that targets EGFR exon 20 mutations with unparalleled kinome selectivity. Preclinical studies revealed strong potency and tumor regressions driven by enozertinib across a broad range of atypical EGFR-mutant models. In a phase I clinical trial of enozertinib in patients with advanced NSCLC bearing atypical mutations in EGFR, a patient harboring an EGFR exon 20 insertion experienced sustained complete response of all systemic and brain metastases. Together, these findings identify enozertinib as a promising investigational inhibitor to address the unmet need for brain-penetrant therapies in NSCLC with EGFR exon 20 insertions or other atypical mutations. SIGNIFICANCE: Preclinical and initial phase I clinical data demonstrate the potency, kinome selectivity, efficacy, and brain penetration of enozertinib in NSCLC with EGFR exon 20 insertions and atypical mutations, warranting further clinical development.

Carcinoma, Non-Small-Cell Lung

Exon inclusion signatures enable accurate estimation of splicing factor activity.

Splicing factors control exon inclusion in messenger RNAs, shaping transcriptome and proteome diversity. Their catalytic activity is regulated by multiple layers, making single-omic measurements on their own fall short in identifying which splicing factors underlie a phenotype. Here, we posit that splicing factor activity can be estimated from changes in exon inclusion. To test this hypothesis, we benchmarked methods for constructing splicing factor&#x2192;exon networks and estimating splicing factor activity. We found that combining RNA-seq perturbation-based networks with VIPER (Virtual Inference of Protein Activity by Enriched Regulon analysis) accurately captures splicing factor activation as modulated by multiple regulatory layers. This approach integrates splicing factor regulation into a single score derived solely from exon inclusion signatures, allowing functional interpretation of heterogeneous conditions. As a proof of concept, we identify recurrent cancer splicing programs, revealing oncogenic- and tumor suppressor-like splicing factors missed by conventional methods. These programs correlate with patient survival and key cancer hallmarks: initiation, proliferation, and immune evasion. Altogether, we show splicing factor activity can be accurately estimated from exon inclusion changes, enabling comprehensive analyses of splicing regulation with minimal data requirements.

VIPER

The mouse neurological mutant flailer expresses a novel hybrid gene derived by exon shuffling between Gnb5 and Myo5a.

Exon shuffling is thought to be an important mechanism for evolution of new genes. Here we show that the mouse neurological mutation flailer (flr) expresses a novel gene that combines the promoter and first two exons of guanine nucleotide binding protein beta 5 (Gnb5) with the C-terminal exons of the closely linked Myosin 5A (MyoVA) gene (Myo5a). The flailer protein, which is expressed predominantly in brain, contains the N-terminal 83 amino acids of Gnb5 fused in-frame with the C-terminal 711 amino acids of MyoVA, including the globular tail domain that binds organelles for intracellular transport. Biochemical and genetic studies indicate that the flailer protein competes with wild-type MyoVA in vivo, preventing the localization of smooth endoplasmic reticulum vesicles in the dendritic spines of cerebellar Purkinje cells. The flailer protein thus has a dominant-negative mechanism of action with a recessive mode of inheritance due to the dependence of competitive binding on the ratio between mutant and wild-type proteins. The chromosomal arrangement of Myo5a upstream of Gnb5 is consistent with non-homologous recombination as the mutational mechanism. To our knowledge, flailer is the first example of a mammalian mutation caused by germ line exon shuffling between unrelated genes.

Amino Acid Sequence

An antisense antidote to oncogenic poison exons.

Splicing factors are frequently mutated in myeloid cancers, causing splicing aberrations that derail the expression of tumor suppressor genes. In SRSF2 mutated cancers, a key oncogenic splicing event is the inclusion of a "poison" exon that introduces an early stop codon in EZH2 mRNA, causing its destabilization. In this issue of Genes & Development, Islam et al. (doi:10.1101/gad.353628.126) define how mutant SRSF2 binding to the poison exon mediates its inclusion and identify an antisense oligonucleotide that represses the exon to restore EZH2 function and rescues hematopoietic defects. Thus, targeting of poison exons, many of which show protumorigenic and antitumorigenic properties, is a promising new avenue to treat cancer.

Oligonucleotides, Antisense

Evolutionary history and recombination in the mitochondrial carrier SLC25 superfamily analyzed by similarities in the exon and transmembrane &#x3b1;-helix sequences.

Mitochondrial carriers (MCs), which constitute a superfamily also called the solute carrier family 25 (SLC25), are characterized by conserved signature motif sequences and a six-transmembrane &#x3b1;-helical transporter domain. They transport a wide variety of substrates ranging from protons, inorganic ions, citric acid cycle intermediates, and amino acids to nucleotides and cofactors. The superfamily members can be divided into subfamilies, each with a distinct substrate specificity. In an attempt to understand how different subfamilies have evolved, we analyzed the protein sequences of the exons (with conserved boundaries) and the six transmembrane &#x3b1;-helices of MCs from highly diverged organisms. The results show that some MC subfamilies have all exons and transmembrane &#x3b1;-helices most similar to a closely related subfamily, which is consistent with a scenario of gene duplication and mutational divergence from a last common ancestor. However, several MC subfamilies appear to be mosaics of exons and transmembrane &#x3b1;-helices most similar to different and distant subfamilies, which in some cases could be explained by recombination between the superfamily genes during evolution. It seems that this latter mechanism could have played a role in the formation of new subfamilies with different substrate specificities by the combination of MC transporter domain segments that had been optimized previously for binding specific portions of the substrates. This study presents novel evolutionary relationships between MC subfamilies and may provide clues for how protein superfamilies have expanded and how to investigate their evolution.

Evolution, Molecular

Functional Motif Discovery in FOXO1 Through CRISPR/Cas9 Exon Tiling Scan.

The study of FOXO1, a pivotal transcription factor, has garnered significant attention due to its critical role in diverse cellular processes, including lineage differentiation, apoptosis, cell cycle regulation, and metabolism. To comprehensively understand the functional intricacies of FOXO1, an innovative approach is essential. This chapter highlights employing CRISPR exon scanning as a strategic tool to dissect the functional domains of FOXO1 and unravel its diverse regulatory functions. CRISPR exon scan allows for the identification of functionally important domains based on the levels of sgRNA depletion or enrichment within the FOXO1 gene, providing a unique opportunity to investigate the domain function under relevant biological contexts. This approach enables the systematic exploration of FOXO1's structural domains, shedding light on how distinct regions contribute to its overall function. The comprehensive exon scan analysis using CRISPR technology allows gaining a nuanced understanding of FOXO1's functional diversity and regulatory mechanisms.

Forkhead Box Protein O1

RNA splicing evidence enables robust classification of BRCA1 exon 18 variants: Results from the ENIGMA consortium.

The Evidence-based Network for the Interpretation of Germline Mutant Alleles (ENIGMA) research consortium conducted a comprehensive study to characterize spliceogenic variants in BRCA1 exon 18. The absence of systematic RNA-based assessment for these variants has led to inconsistent interpretation, limiting accurate classification and management of individuals and their families. The splicing profile of 166 variants was assessed using minigene assays; 32 were additionally analyzed in blood-derived RNA from 51 individuals and 18 in mouse embryonic stem cell (mESC)-based assays to evaluate homology-directed repair (HDR) capacity. mRNA assessment by RT-PCR in blood samples and minigene assays showed a significant positive correlation, with splicing analysis in mESCs displaying highly concordant results. The mESC-based HDR assay showed that the in-frame exon 18 skipping (&#x394;18) transcript encodes a non-functional protein lacking rescue activity. Linear regression analysis using mESC splicing and functional data indicated that &#x2265;59% of full-length (FL) levels and <34% of &#x394;18 were associated with benign HDR activity. These thresholds differ from those recommended by the ClinGen ENIGMA BRCA1 and BRCA2 Variant Curation Expert Panel American College of Medical Genetics and Genomics (ACMG)/Association for Molecular Pathology (AMP) specifications for applying BP7_strong(RNA): >30% functional transcripts or <70% non-functional transcripts. Incorporation of RNA splicing evidence into variant interpretation increased pathogenic (28.6%-31.7%) and benign (3.7%-24.4%) classifications while reducing likely pathogenic (19.5%-17.7%), uncertain (18.9%-8.5%), and likely benign (29.3%-17.7%) categories. Experimental mRNA profiling impacted the interpretation of 34% of variants and resolved uncertainty in approximately 10% of cases. Exon 18 skipping was less tolerated, indicating that the degree of splice perturbation required to impair BRCA1 function may depend on the nature of the resulting non-functional transcript.

Humans

Efficacy of EGFR tyrosine kinase inhibitors in patients with non-small cell lung cancer with EGFR exon 19 insertions: clinical-genomic, preclinical analysis through LC-SCRUM-Asia (multi-institutional genomic screening registry).

BACKGROUND: EGFR exon 19 insertions (EGFRex19ins) are rare EGFR mutations. Their clinical-genomic characteristics and outcomes with EGFR-tyrosine kinase inhibitors (TKIs) remain uncertain. METHODS: We evaluated the clinical-genomic characteristics and outcomes of EGFR-TKIs for EGFRex19ins in the multi-institutional prospective lung cancer genomic screening project (LC-SCRUM-Asia). We also studied preclinical Ba/F3 models expressing EGFR-K745_E746insIPVAIK (Ba/F3-IPVAIK) to investigate their sensitivity to 1st-, 2nd-, 3rd-generation, and EGFR exon 20 insertion-active TKIs. RESULTS: In LC-SCRUM-Asia, 16,204 NSCLC patients were enrolled from March 2015 to December 2023. EGFRex19ins were detected in 13 samples (0.1&#xa0;% of NSCLC). The median age was 72&#xa0;years (range, 38-80); most patients were female (77&#xa0;%), had adenocarcinoma (92&#xa0;%), and were never-smokers (62&#xa0;%). Twelve patients (93&#xa0;%) had EGFR-K745_E746insIPVAIK, while one (7&#xa0;%) had EGFR-K745_E746insVPVAIK. The most frequent co-mutation was TP53 (62&#xa0;%); no patients had other driver alterations. Six patients (46&#xa0;%) tested positive for EGFR exon 19 deletions with PCR-based Cobas EGFR test, likely due to cross-reactivity arising from sequence homology. Twelve patients received EGFR-TKIs; five (42&#xa0;%) experienced partial response. In the preclinical study, Ba/F3-IPVAIK showed the highest sensitivity to 2nd-generation EGFR-TKIs compared to other EGFR-TKIs. Structural studies supported these consistent results. When broken down by EGFR-TKI generations, response rates for 1st-, 2nd-, and 3rd-generation TKIs were 50&#xa0;% (1/2), 80&#xa0;% (4/5), and 0&#xa0;% (0/5), respectively. The median PFS for 1st-, 2nd-, and 3rd-generation TKIs were 8.7 (95&#xa0;% CI, 7.4-NR), 14.7 (95&#xa0;% CI, 8.0-NR), and 4.4 (95&#xa0;% CI, 3.4-NR) months, respectively. CONCLUSION: Our preclinical, structural, and clinical findings indicate 2nd-generation EGFR-TKIs are more effective for EGFRex19ins compared to other TKIs.

Adult

CLOCK gene 3'UTR and exon 9 polymorphisms show a strong association with essential hypertension in a North Indian population.

BACKGROUND: Hypertension (HTN) is a medical condition characterized by persistent systolic and diastolic blood pressures of &#x2265;&#x2009;140 mmHg and &#x2265;&#x2009;90 mmHg, respectively. With more than 1200&#xa0;million adult patients aged 30-79 years worldwide according to the latest WHO data, HTN is a major health risk factor; more importantly, 46% of patients are unaware of this condition. Essential hypertension (EH), also known as primary hypertension, is the predominant subtype and has a complex etiology that involves both genetic and non-genetic factors. Majority of living organisms are influenced by the light and dark cycle of a day and respond to these changes through an intricate clock referred to as the "biological clock" or "circadian rhythm". The connection between circadian rhythm and blood pressure is well established, with many studies supporting the role of circadian rhythm gene mutation(s)/polymorphism(s) in EH. To date, no such data are available from any Indian population. METHODS: This case&#x2012;control study was conducted on 405 EH patients and 505 healthy controls belonging to the Jammu region of North India after an informed consent was obtained from the participants. A total of three single nucleotide variants, two in the CLOCK gene (rs1801260 and rs34789226) and one in the BMAL1/ARNTL gene (rs6486121), were selected for genotyping. Genotyping was performed via the RFLP technique, and the applicable statistical analyses were performed via the SPSS and SNPStats programs. RESULTS: Logistic regression analysis revealed a statistically significant association of both CLOCK gene variants rs1801260 (T&#x2009;>&#x2009;C 3'UTR) and rs34789226 (C&#x2009;>&#x2009;T Exon 9) and a nonsignificant association of the BMAL1/ARNTL intronic variant rs6486121 (C&#x2009;>&#x2009;T) with EH. The 3'UTR variant showed a statistically significant association under the codominant (p&#x2009;<&#x2009;0.0001), dominant (p&#x2009;<&#x2009;0.0001), and recessive (p&#x2009;=&#x2009;0.0004) models. In contrast, the exon 9 variant showed a statistically significant negative association under the codominant (p&#x2009;=&#x2009;0.003) and dominant (p&#x2009;=&#x2009;0.015) models only. The rs6486121/rs1801260 and rs1801260/rs34789226/rs6486121 haplotypes showed significant differences in their distribution between cases and controls (p&#x2009;<&#x2009;0.0001). Certain genotypes and haplotypes were found more common in hypertensive males than females. CONCLUSION: This is a first report linking circadian rhythm gene polymorphisms with EH in any Indian population. The statistically significant association of the CLOCK gene 3'UTR and exon 9 polymorphisms with EH, highlight the potential role of this gene and probably other genes of the circadian pathway in the etiology of EH in the study population. Additionally, our study also revealed that certain genotypes are making males more susceptible to EH.

Humans

U2AF1 mutations rescue deleterious exon skipping induced by KRAS mutations.

The mechanisms by which somatic mutations of splicing factors, such as U2AF1S34F in lung adenocarcinoma, contribute to cancer pathogenesis are not well understood. Here, we used prime editing to modify the endogenous U2AF1 gene in lung adenocarcinoma cells and assessed the resulting impact on alternative splicing. These analyses identified KRAS as a key target modulated by U2AF1S34F. One specific KRAS mutation, G12S, generates a cryptic U2AF1 binding site that leads to skipping of KRAS exon 2 and generation of a non-functional KRAS transcript. Expression of the U2AF1S34F mutant reverts this exon skipping and restores KRAS function. Analysis of cancer genomes reveals that U2AF1S34F mutations are enriched in KRASG12S-mutant lung adenocarcinomas. A comprehensive analysis of splicing factor/oncogene mutation co-occurrence in cancer genomes also revealed significant co-enrichment of KRASQ61R and U2AF1I24T mutations. Experimentally, KRASQ61R mutation leads to KRAS exon 3 skipping, which in turn can be rescued by the expression of U2AF1I24T. Our findings provide evidence that splicing factor mutations can rescue splicing defects caused by oncogenic mutations. More broadly, they demonstrate a dynamic process of cascading selection where mutational events are positively selected in cancer genomes as a consequence of earlier mutations.

Journal Article

Rapidly progressive steroid-resistant focal segmental glomerulosclerosis associated with an INF2 exon 6 variant.

Variants in the inverted formin-2 (INF2) gene are a known cause of hereditary focal segmental glomerulosclerosis (FSGS) and Charcot-Marie-Tooth disease. We report a case of rapidly progressive FSGS associated with a rare INF2 variant. A 12-year-old boy developed proteinuria and was diagnosed with FSGS at age 14 following a renal biopsy. Steroid therapy and subsequent immunosuppressive treatments, including plasma exchange, were ineffective. At age 15, a heterozygous missense variant in exon 6 of the INF2 gene (c.763G>A, p.Asp255Asn) was identified. Despite conservative management, the patient progressed to end-stage kidney disease at age 17. Although exon 6 variants are rarely reported, the present case showed a relatively aggressive renal course.

Humans