C3- and C5-nephritic factors are potent but poorly understood autoantibodies that dysregulate complement convertases. To date, their underlying mechanisms of action, epitopes, and sequences remain unknown. To address this knowledge gap, we immune profiled B cells from a nephritic factor-positive C3 glomerulopathy patient and identified the first monoclonal C3- and C5-nephritic factors. We present the structure of a C3-nephritic factor bound to a C3 convertase with the convertase protease domain unexpectedly rotated and inhibited. This rotation advances our understanding of complement convertase progression and decay, explains disease-associated convertase variants, and reveals the molecular mechanism by which nephritic factors can either activate or inhibit convertase activity. We also detail heterogeneity within and between C3- and C5-nephritic factors in terms of convertase binding, stabilizing capacity, regulator inhibition, fluid-phase activation, and disease contribution. These findings improve stratification of patients with C3 glomerulopathy, redefine basic C3 convertase dynamics, and provide insights into antibody-mediated modulation of the complement system.

Current understanding of the structure, function, and molecular dynamics of the alternative pathway C3-convertase has been shaped by the clinical impact of genetic variants in complement genes. Characterizing the functional impact of different mutations not only provides patient-specific insights into the pathogenic mechanisms underlying a number of complement-mediated diseases but, at a broader level, allows us to dissect the molecular underpinnings of protein-protein interactions that drive complement amplification and its control. In this review, we contextualize over 100 variants in C3, CFB, CFD, CFH, and CFI to illustrate how this collective knowledge informs known mechanisms of complement biology and illuminates gaps that remain to be defined.

Complement 3 glomerulopathy (C3G) is a rare complement-mediated kidney disease characterized by overactivation of the alternative pathway (AP). C3G encompasses 2 subtypes, dense deposit disease and C3 glomerulonephritis, both of which lead to C3 deposition in the glomeruli, progressive kidney dysfunction, and, ultimately, kidney failure. The pathophysiology of C3G and the underlying complement AP overactivation are often driven by genetic variants and/or acquired autoantibodies. These systemic drivers can affect native and transplanted kidneys; thus, C3G is associated with a high risk of recurrence in allografts. Recurrence of C3G in posttransplant kidneys has a particularly poor prognosis and leads to a high rate of graft loss. Therapeutic strategies for native and posttransplant recurrent C3G that are largely supportive have shown limited benefit in improving kidney survival, as have therapies targeting the terminal complement cascade downstream of pathogenic AP overactivation. In contrast, emerging therapies that target AP overactivation are showing promise for more effective disease modification. In light of the evolving treatment landscape, this review provides an update on the current state of knowledge regarding the pathophysiology, prognosis, and treatment options for native and posttransplant recurrent C3G.

Pathogenic variation of SLC26A4 gene causes both Pendred syndrome (PDS) and non-syndromic enlarged vestibular aqueduct (NSEVA/DFNB4), two autosomal recessive disorders. The former accounts for approximately 6

Objective(s)Autosomal dominant nonsyndromic hearing loss (ADNSHL) is a genetically heterogeneous disorder. Copy-number and structural variants (SVs) in EYA4 are a rare cause of hearing loss at the DFNA10 locus. We aimed to determine the genetic etiology of hearing loss in a series of families with ADNSHL.MethodsWe performed a retrospective review of patients referred for targeted genomic enrichment and massively parallel sequencing using the OtoSCOPE panel, which covers known genes associated with nonsyndromic hearing loss (NSHL). Genetic findings and available phenotypic data were reviewed by a multidisciplinary team to assess variant pathogenicity. Haplotypes were reconstructed using variants in EYA4 and flanking regions.ResultsA novel pathogenic SV in EYA4 involving a 5.8 kb deletion of the Terminal Exons 19 and 20, with insertion of a short, inverted downstream sequence, was identified in five North American probands with a family history consistent with ADNSHL. Segregation analysis demonstrated cosegregation with hearing loss in two affected relatives. This SV is the most frequently detected pathogenic variant in EYA4 in our cohort, accounting for five of 25 (20%) DFNA10 diagnoses to date. Haplotype reconstruction demonstrated an extended shared 857 kB haplotype surrounding the region.ConclusionThis study expands the mutational spectrum of EYA4-associated hearing loss. The complexity of this novel SV, its identical breakpoint structure, and shared haplotype support a founder origin of this allele rather than a recurrent event. These findings highlight the importance of systematic and comprehensive CNV/SV analysis in routine genetic testing for hearing loss and show that clinically relevant complex SVs may be overlooked without careful evaluation.

Background:Autosomal dominant nonsyndromic hearing loss (ADNSHL) is highly heterogeneous, with more than 64 genes implicated in its etiology. This complexity limits the diagnostic power of clinical examinations and audiometry alone, while existing computational approaches have achieved only moderate accuracy and often lack interpretability. As precision medicine increasingly emphasizes genotype-phenotype correlations, there is a recognized need for diagnostic tools that provide clinicians with transparent, interpretable outputs. Objective:This study aimed to develop and evaluate the AudioGene Translational Dashboard, an interpretable clinical informatics tool that integrates machine learning models and interactive visualizations to enhance genotype-phenotype correlations and support diagnostic decision-making in ADNSHL. Methods:We developed the AudioGene Translational Dashboard, integrating 2 machine learning models (AudioGene version 4 and AudioGene version 9.1) with 6 interactive visualization tools. AudioGene version 4 uses a multi-instance support vector machine classifier for patients with multiple audiograms, while AudioGene version 9.1 combines adaptive boosting, k-nearest neighbors, random forest models, and logistic regression for patients with a single audiogram. Visualizations include audiometric profile plots, audioprofile surfaces, clustering analyses, and data distribution charts designed to facilitate clinical interpretation. Results:The AudioGene Translational Dashboard was developed to address the "70/30" phenomenon, indicating a 74% likelihood that the causative gene is among the top 3 predicted genes, thereby providing clinicians with a clear confidence indicator ("green flag") or a caution alert ("red flag") during diagnosis. While this level of performance is well suited for hypothesis generation, the remaining uncertainty underscores the need for interpretive context in clinical decision-making. Visualization tools enhanced clinicians' ability to interpret and correlate phenotypic data with predicted genetic outcomes, improving diagnostic confidence and interpretability. Conclusions:The AudioGene Translational Dashboard advances clinical informatics in genetic diagnosis of ADNSHL by integrating explainable artificial intelligence with interactive visualizations, enhancing clinical interpretability and diagnostic accuracy. This approach facilitates informed clinical decision-making, highlights the translational potential of genotype-phenotype computational models, and supports precision medicine in hearing loss diagnostics. Future enhancements will target improving class balance and incorporating additional user-customizable features to further optimize clinical applicability.

C3 glomerulopathy-primary immune complex membranoproliferative glomerulonephritis (C3G/IC-MPGN) is an ultrarare disease spectrum associated with a significant health burden and for which there is a huge unmet need for safe and effective treatment. The underlying pathophysiology is dysregulation and overactivation of the alternative complement pathway. Two new therapeutic agents, iptacoplan and pegcetacoplan, that target proximal steps in the cascade, have demonstrated to be effective and have been approved for use in patients with C3G alone and with C3G/IC-MPGN, respectively. A key challenge to the nephrology community is how to incorporate these disease-modifying drugs into clinical practice in a timely and equitable manner. This report summarizes the deliberations and recommendations that emerged from the SEISMIC (Addressing access issues in diagnosis and treatment of C3G nephropathy and IC-MPGN) summit in July 2025. The meeting assembled a broad panel of experts and patients and addressed the following three aims: 1) define issues in proper and timely diagnosis of this complex disease spectrum, 2) assess management strategies in light of the availability of this new class of therapeutic agents, and 3) identify barriers to access to care and treatment with these new therapeutic agents and design strategies to surmount them.

C3 glomerulopathy (C3G) is a group of heterogeneous ultrarare kidney diseases characterized by dysregulated activation of the complement alternative pathway (AP) leading to excessive C3 cleavage. Diagnosis relies on kidney biopsy showing predominant C3 deposition in the glomerular basement membrane, with electron microscopy differentiating between dense deposit disease (DDD) and C3 glomerulonephritis (C3GN). The main drivers of AP dysregulation in C3G are acquired rather than genetic and consist primarily of autoantibodies called nephritic factors (C3Nefs, C4Nefs and C5Nefs) that bind to and stabilize complement convertases, causing complement overactivation. Current therapies are largely supportive, and existing complement-targeting treatments, such as eculizumab, demonstrate limited efficacy. Challenges in studying C3G include variability in autoantibody detection and a lack of standardized assays, which complicates clinical interpretation. Comprehensive assessment involving autoantibody panels, complement biomarkers, functional assays and genetic testing provides a more complete understanding of disease dynamics; however, key knowledge gaps remain regarding Nef origins, mechanisms and their pathogenic role. In this review we discuss acquired drivers of C3G with an emphasis on C3Nefs and C5Nefs and suggest areas of interest that might benefit from future research.

PURPOSE:The Clinical Genome Resource (ClinGen) Hearing Loss Gene Curation Expert Panel was assembled in 2016 and has since curated 174 gene-disease relationships (GDRs) using ClinGen's semiquantitative framework. ClinGen mandates the timely recuration of all GDRs classified as Disputed, Limited, Moderate, and Strong every 2 to 3 years. METHODS:Thirty-five GDRs met the criteria for recuration within 2 years of original curation. Previous evidence was reevaluated using the latest curation guidelines, and a comprehensive literature review was performed to obtain new evidence. Recurations were approved by the Gene Curation Expert Panel and published on the ClinGen website (www.clinicalgenome.org). RESULTS:Eight of 35 GDRs (22%) changed their classification. Two Moderate and 5 Strong GDRs were upgraded to Definitive because of new case evidence. One Strong was subsumed under another Definitive GDR after evaluation of the lumping/splitting of disease entities. Twenty-seven of 35 patients remained unchanged, with little to no new evidence reported. CONCLUSION:Genes classified as Moderate and Strong were likely to build evidence and change their classification over time, whereas Limited were unlikely to gain evidence. These findings highlight the critical role of recuration in ensuring that genetic tests and research studies incorporate the most recent evidence into their efforts.

Despite advances in the genetic diagnosis of hearing loss, there remains room for improvement. One way to improve the genetic diagnostic rate is the proper assessment of synonymous variants that are often bioinformatically filtered out. We used GSDME as a model to demonstrate the importance of assessing synonymous variants. Variants in the gene GSDME (also known as DFNA5) are associated with autosomal dominant nonsyndromic hearing loss. The hearing loss is typically progressive and downsloping. All reported causative variants of GSDME-related hearing loss involve the skipping of exon 8, which results in the expression of a constitutively active, but truncated protein that induces apoptosis of cochlear hair cells. A retrospective search of previously tested patients identified 3 novel pathogenic synonymous GSDME variants. The functional impact of these variants was confirmed in vitro via a minigene splicing assay. We also observed variant-dependent differences in the levels of aberrant splicing, leading us to hypothesize that partial loss of splicing will result in a less severe hearing loss phenotype as compared to complete loss of splicing. Audiometric analysis found an association between complete loss of splicing and greater initial and/or more quickly progressing hearing loss as compared to partial loss of splicing. Over the course of the study, we also found limited correlation between in silico prediction and in vitro observed effects of a variant on splicing, indicating the need to cautiously apply in silico prediction tools in the context of genetic diagnosis.

Syndromic hearing loss that results from contiguous gene deletions is uncommon.Three families with a novel syndrome characterised by deafness and infertility are described. Linkage was established by completing a genome-wide scan and candidate genes in the linked region were screened by direct sequencing. The deleted region is about 100 kb long and involves four genes (KIAA0377, CKMT1B, STRC and CATSPER2), each of which has a telomeric duplicate. This genomic architecture underlies the mechanism by which these deletions occur. CATSPER2 and STRC are expressed in the sperm and inner ear, respectively, consistent with the phenotype in persons homozygous for this deletion. A deletion of this region has been reported in one other family segregating male infertility and sensorineural deafness. We have identified three families segregating an autosomal recessive contiguous gene deletion syndrome characterised by deafness and sperm dysmotility. This new syndrome is caused by the deletion of contiguous genes at 15q15.3.

C3 Glomerulopathy (C3G) is an ultra-rare glomerular disease driven by dysregulation of the alternative pathway of complement. 30–50

In vitro studies and observational human disease data suggest the complement system contributes to SARS-CoV-2 pathogenesis, although how complement dysregulation develops in severe COVID-19 is unknown. Here, using a mouse-adapted SARS-CoV-2 virus (SARS2-N501YMA30) and a mouse model of COVID-19, we identify significant serologic and pulmonary complement activation post-infection. We observed C3 activation in airway and alveolar epithelia, and pulmonary vascular endothelia. Our evidence suggests the alternative pathway is the primary route of complement activation, however, components of both the alternative and classical pathways are produced locally by respiratory epithelial cells following infection, and increased in primary cultures of human airway epithelia following cytokine and SARS-CoV-2 exposure. This tissue-specific complement response appears to precede lung injury and inflammation. Our results suggest that complement activation is a defining feature of severe COVID-19 in mice, agreeing with previous publications, and provide the basis for further investigation into the role of complement in COVID-19.

The transcription factor Lmx1a is widely expressed during early inner ear development, and mice lacking Lmx1a expression exhibit fusion of cochlear and vestibular hair cells and fail to form the ductus reuniens and the endolymphatic sac. Lmx1a dreher (Lmx1adr/dr), a recessive null mutation, results in non-functional Lmx1a expression, which expands from the outer sulcus to the stria vascularis and Reissner’s membrane. In the absence of Lmx1a, we observe a lack of proteins specific to the stria vascularis, such as BSND and KCNQ1 in marginal cells and CD44 in intermediate cells. Further analysis of the superficial epithelial cell layer at the expected stria vascularis location shows that the future intermediate cells migrate during embryonic development but subsequently disappear. Using antibodies against pendrin (Slc26a4) in Lmx1a knockout (KO) mice, we observe an expansion of pendrin expression across the stria vascularis and Reissner’s membrane. Moreover, in the absence of Lmx1a expression, no endocochlear potential is observed. These findings highlight the critical role of Lmx1a in inner ear development, particularly in the differentiation of cochlear and vestibular structures, the recruitment of pigment cells, and the expression of proteins essential for hearing and balance.

In this paper, we demonstrate for the first time the focusing of gigahertz coherent phonon pulses propagating in water using picosecond ultrasonics and Brillouin light scattering. We achieve this by using planar Fresnel zone plate and concave lenses with different focal lengths. Pump light illuminating the optoacoustic lens generates a focusing acoustic field, and Brillouin scattered probe light allows the acoustic field to be continuously monitored over time. Agreement of the experiment with a numerical model suggests that we can generate a focused acoustic beam down to ∼250 nm. A clear focusing effect is observed experimentally as a modulation of the envelope of the time-resolved Brillouin scattering (TRBS) signal. These findings are a crucial step toward their application in high-resolution acoustic microscopy. This work experimentally demonstrates a method to narrow the lateral size of picosecond laser-generated phonon fields in an aqueous environment, making it well-suited for 3D imaging applications in biological systems using TRBS.

Factor H (FH) is a crucial complement regulator that prevents complement-mediated injury to healthy cells and tissues. This regulatory function can be disrupted by Factor H autoantibodies (FHAA), which then leads to diseases such as atypical hemolytic uremic syndrome (aHUS) and C3 Glomerulopathy (C3G). In pediatric aHUS, the FHAA incidence is ~10-15%, although in the Indian population, it rises to ~50%. The specific regions of FH targeted by FHAAs correlate with the pathogenic mechanism of the associated disease. In aHUS, FHAAs target the C-terminus, thereby impacting FH ability to recognize cell surfaces. In C3G, in contrast, FHAAs often target the N-terminus, generating an acquired functional FH deficiency. Detection and monitoring FHAAs are decisive for effectively treating patients. Current FHAA analysis normally identify free FHAAs that bind surface-bound FH using ELISA techniques. These methods require well-equipped laboratories and qualified staff, and do not measure FH-FHAA complexes, which can make it difficult to correlate titers with clinical outcomes. The visually-based immunochromatographic test (ICT) described herein allows for quick detection and quantification of IgG and IgM FH-FHAA complexes in human EDTA-plasma or serum. This ICT offers improved detection of FHAAs compared to ELISA as demonstrated by cases where the ICT identifies FH-FHAA complexes in samples that tested negative with the free FHAA ELISA. Importantly, the ICT indirectly informs on the amount of FH that is complexed with FHAAs, thus assessing the significance of the FHAA in disrupting the regulatory function of FH. Overall, this novel assay offers a simple, fast, cost-effective, and, likely, more clinically relevant alternative for diagnosing FHAAs in at-risk populations.

Importance: Understanding the potential risks associated with fertility treatments (FTs) can guide clinical decision and patient counseling. Objective: To investigate the validity of the association between the development of female-specific malignancies including ovarian, endometrial, breast, and cervical cancer after FT. Data Sources: A search of systematic reviews and meta-analyses was performed from inception to April 2022 within several databases: Cochrane Database of Systematic Reviews, EMBASE, Google Scholar, and PubMed. Study Selection and Synthesis: The inclusion criteria required the incidence of each cancer subgroup to be stated in both the defined treatment group (controlled ovarian stimulation and/or in vitro fertilization [IVF] or intracytoplasmic sperm injection) and the control group (no-FT, general population). From 3,129 identified publications, 11 meta-analytical reviews consisting of 188 studies were selected for synthesis. Main Outcome: The primary outcome of interest was incidence of each subgroup of cancer in the "FT"group compared with the "no-FT"group. Results: A statistically significant increase in incidence of ovarian (1,229/430,611 in FT group vs. 27,358/4,263,300 in no-FT group) cancer (odds ratio [OR], 1.21; 95% confidence interval [CI], 1.00-1.45) and borderline ovarian tumors (117/414,729 in FT group vs. 934/ 2,626,324 in no-FT group) (OR, 1.87; 95% CI, 1.18-2.97) was observed. The incidence of ovarian cancer was higher with FT and IVF specifically (OR, 1.65; 95% CI, 1.07-2.54). For borderline ovarian tumors, the incidence was higher, not only with FT overall and IVF, but also according to the fertility drug regimen applied: clomiphene citrate (CC) only (OR, 1.99; 95% CI, 1.02-3.87), human menopausal gonadotropin only (OR, 3.46; 95% CI, 1.39-8.59), and CC and human menopausal gonadotropin combined (OR, 3.79; 95% CI, 1.47-9.77). When using the threshold for statistical significance, the meta-analyses relevant to ovarian cancers remained statistically significant (random-effects method). However, none of the examined associations could claim either strong or highly suggestive evidence. Conclusion and Relevance: An observed association between ovarian cancer (including borderline ovarian tumors) and FT has been demonstrated. The association between FT and female-specific malignancy remains a contentious topic because there have been contradictory outcomes among meta-analyses. This umbrella review interrogates existing systematic reviews and meta-analyses on this topic and concludes that a statistically significant increase in the incidence of ovarian cancer and borderline ovarian tumors is associated with FT. These findings have a significant clinical impact because it helps to inform and provide effective counseling for patients undergoing FT. (Fertil Steril (R) 2025;123:506-19. (c) 2024 by American Society for Reproductive Medicine.) El resumen est & aacute; disponible en Espa & ntilde;ol al final del art & iacute;culo.