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Alport syndrome (AS) is a hereditary disease caused by mutations in the COL4A5 gene and leads to chronic kidney disease. Currently, no specific treatment has been developed. However, a recent study using AS-model mice demonstrated that the exon skipping method could partially rescue the symptoms. In this study, we evaluated the effects of the exon skipping method using kidney organoids generated from AS-patient-derived induced pluripotent stem cells (AS-iPSCs). We generated kidney organoids from AS-iPSCs, which exhibited nephron structures. As expected, the C-terminus of COL4A5 was not expressed in AS-organoids. Interestingly, anti-sense oligonucleotides restored the expression of the C-terminus of COL4A5 in vitro. Next, we transplanted AS-organoids into mice and evaluated glomerular basement membrane formation in vivo. We found that AS-organoids formed a lower slit diaphragm ratio compared to control organoids. Finally, we assessed the effects of exon skipping on transplanted organoids but observed minimum effects. These studies suggest that AS-iPSCs can generate kidney organoids lacking the C-terminus of COL4A5, and that exon skipping can induce its expression in vitro., (© 2024 The Author(s). Genes to Cells published by Molecular Biology Society of Japan and John Wiley & Sons Australia, Ltd.)

Alport syndrome (AS) is characterized by progressive kidney failure, hematuria, sensorineural hearing loss, and ocular abnormalities. Pathogenic variants in the COL4A3-5 genes result in a defective deposition of the collagen IV α3α4α5 protomers in the basement membranes of the glomerulus in the kidney, the cochlea in the ear and the cornea, lens capsule and retina in the eye. The presence of a large variety of COL4A3-5 gene(s) pathogenetic variants irrespective of the mode of inheritance (X-linked, autosomal recessive, autosomal dominant, or digenic) with and without syndromic features is better defined as the "Alport spectrum disorder", and represents the most common cause of genetic kidney disease and the second most common cause of genetic kidney failure. The clinical course and prognosis of individuals with AS is highly variable. It is influenced by gender, mode of inheritance, affected gene(s), type of genetic mutation, and genetic modifiers. This review article will discuss the epidemiology, classification, pathogenesis, diagnosis, clinical course with genotype-phenotype correlations, and current and upcoming treatment of patients with AS. It will also review current recommendations with respect to when to evaluate for hearing loss or ophthalmologic abnormalities., (Copyright © 2024. Published by Elsevier Inc.)

Alport syndrome is one of the most common inherited kidney diseases caused by mutations in the type Ⅳ collagen genes. It has a complex pattern of inheritance and diverse clinical manifestations, and severe cases will rapidly progress to end-stage kidney disease. With the rapid development of genetic testing technology, there is a deeper understanding of the genetic spectrum of Alport syndrome, the effectiveness of clinical therapies, and the prediction of disease prognosis. Therefore, the purpose of the article is to introduce the advances in the diagnosis and treatment of Alport syndrome, aiming to improve the early diagnosis and standardized treatment of this disease.

Introduction: Alport syndrome (AS) is one of the most common fatal hereditary renal diseases in human, with a high risk of progressing to end-stage renal disease without effective treatments. Mesenchymal stem cells (MSCs) have recently emerged as a promising therapeutic strategy for chronic kidney disease. However, the safety and therapeutic potential of MSC transfusion for patients with AS are still need to be confirmed. Therefore, we have designed a clinical trial to evaluate the hypothesis that intravenous infusion of human umbilical cord-derived MSC (hUC-MSC) is safe, feasible, and well-tolerated in children with AS., Methods and Analysis: We report the protocol of the first prospective, open-label, single-arm clinical trial to evaluate the safety and preliminary efficacy of hUC-MSC transfusion in children with early-stage AS. Paediatric patients diagnosed with AS who have persistent albuminuria will be candidates for screening. Twelve eligible patients are planned to recruit and will receive hUC-MSC infusions under close safety monitoring, and complete the efficacy assessments at scheduled follow-up visits. The primary endpoints include the occurrence of adverse events to assess safety and the albuminuria level for efficacy evaluation. Secondary endpoint assessments are based on haematuria and glomerular filtration measurements. Each patient's efficacy endpoints will be evaluated against their baseline levels. Additionally, the underlying mechanism of hUC-MSC therapy will be explored through transcriptomic and proteomic analysis of blood and urine samples., Ethics and Dissemination: The protocol (V.1.0, date 17 January 2015) was approved by the institutional review board of the Affiliated Taihe Hospital of Hubei University of Medicine (ethical approval 03 March 2015). Written informed consent will be obtained from the patient and/or guardians before study specific process. In addition to publication in a peer-reviewed scientific journal, a lay summary of study will be available for participants and the public on the Chinese Organization for Rare Disorders website (http://www.cord.org.cn/)., Trial Registration Number: ISRCTN62094626., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Alport syndrome (AS) is a hereditary glomerulonephritis caused by COL4A3, COL4A4 or COL4A5 gene mutations and characterized by abnormalities of glomerular basement membranes (GBMs). Due to a lack of curative treatments, the condition proceeds to end-stage renal disease even in adolescents. Hampering drug discovery is the absence of effective in vitro methods for testing the restoration of normal GBMs. Here, we aimed to develop kidney organoid models from AS patient iPSCs for this purpose. We established iPSC-derived collagen α5(IV)-expressing kidney organoids and confirmed that kidney organoids from COL4A5 mutation-corrected iPSCs restore collagen α5(IV) protein expression. Importantly, our model recapitulates the differences in collagen composition between iPSC-derived kidney organoids from mild and severe AS cases. Furthermore, we demonstrate that a chemical chaperone, 4-phenyl butyric acid, has the potential to correct GBM abnormalities in kidney organoids showing mild AS phenotypes. This iPSC-derived kidney organoid model will contribute to drug discovery for AS., (© 2023. The Author(s).)

Background: Alport syndrome is one of the most common inherited kidney diseases worldwide. A genetic test or kidney biopsy is necessary for a definite diagnosis of this disease, and an accurate diagnosis system for this disease is highly desired in each country. However, the current situation in Asian countries is not clear. Therefore, the tubular and inherited disease working group of the Asian Pediatric Nephrology Association (AsPNA) aimed to assess the current situation of diagnosis and treatment for Alport syndrome in Asia., Methods: The group conducted an online survey among the members of AsPNA in 2021-2022. Collected data included the number of patients for each inheritance mode, availability of gene tests or kidney biopsy, and treatment strategies for Alport syndrome., Results: A total of 165 pediatric nephrologists from 22 countries in Asia participated. Gene test was available in 129 institutes (78%), but the cost was still expensive in most countries. Kidney biopsy was available in 87 institutes (53%); however, only 70 can access electron microscopy, and 42 can conduct type IV collagen α5 chain staining. Regarding treatment, 140 centers use renin-angiotensin system (RAS) inhibitors (85%) for Alport syndrome patients., Conclusions: This study result might suggest that the system is underdeveloped enough to diagnose all Alport syndrome patients in most Asian countries. However, once diagnosed with Alport syndrome, most of them were treated with RAS inhibitors. These survey results can be used to address knowledge, diagnostic system, and treatment strategy gaps and improve the Alport patients' outcomes in Asian countries., (© 2023. The Author(s).)

The "Expert Recommendations on the Diagnosis and Treatment of Alport Syndrome" published in 2018 have greatly promoted the standardized management of Alport syndrome in China. In recent years, the rapid advances in researches related to this disorder have provided new insights into the clinical practice of Alport syndrome. To this end, based on the latest research progress at home and abroad, the Alport Syndrome Collaborative Group, the National Clinical Research Center of Kidney Diseases of Jinling Hospital and the Rare Diseases Branch of Beijing Medical Association have jointly organized the experts in relevant fields to revise the 2018 version of the recommendations. The updated version adds new contents related to genetic testing and variant interpretation, and refines the strategies for diagnosis, treatment and follow-up management, thereby providing guidance for the clinical diagnosis and treatment of Alport syndrome.

Nonsense mutations trigger premature translation termination and often give rise to prevalent and rare genetic diseases. Consequently, the pharmacological suppression of an unscheduled stop codon represents an attractive treatment option and is of high clinical relevance. At the molecular level, the ability of the ribosome to continue translation past a stop codon is designated stop codon readthrough (SCR). SCR of disease-causing premature termination codons (PTCs) is minimal but small molecule interventions, such as treatment with aminoglycoside antibiotics, can enhance its frequency. In this review, we summarize the current understanding of translation termination (both at PTCs and at cognate stop codons) and highlight recently discovered pathways that influence its fidelity. We describe the mechanisms involved in the recognition and readthrough of PTCs and report on SCR-inducing compounds currently explored in preclinical research and clinical trials. We conclude by reviewing the ongoing attempts of personalized nonsense suppression therapy in different disease contexts, including the genetic skin condition epidermolysis bullosa.

Recent trends in the diagnosis, treatment, and classification of collagen IV-associated kidney disease are likely to result in increasing numbers of people in adult nephrology practices who have a confirmed diagnosis of Alport syndrome. These trends include the increasing use of genetic testing in the diagnostic evaluation of people with hematuria, focal segmental glomerulosclerosis, and chronic kidney disease of unknown etiology; early treatment with inhibitors of the renin-angiotensin-aldosterone system to delay kidney failure; and application of an expanded definition of Alport syndrome based on genotype rather than phenotype. This commentary discusses these trends and their implications for the adult nephrologist., (Copyright © 2021 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Purpose of Review: In Alport syndrome, over 1,700 genetic variants in the COL4A3, COL4A4, and COL4A5 genes cause the absence or malfunctioning of the collagen IVα345 scaffold - an essential component of the glomerular basement membrane (GBM). Therapies are limited to treatment with Angiotensin-Converting enzyme (ACE) inhibitors to slow progression of the disease. Here, we review recent progress in therapy development to replace the scaffold or restore its function., Recent Findings: Multiple approaches emerged recently for development of therapies that target different stages of production and assembly of the collagen IVα345 scaffold in the GBM. These approaches are based on (1) recent advances in technologies allowing to decipher pathogenic mechanisms that underlie scaffold assembly and dysfunction, (2) development of DNA editing tools for gene therapy, (3) RNA splicing interference, and (4) control of mRNA translation., Summary: There is a growing confidence that these approaches will ultimately provide cure for Alport patients. The development of therapy will be accelerated by studies that provide a deeper understanding of mechanisms that underlie folding, assembly, and function of the collagen IVα345 scaffold., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc.)

Genetic testing for pathogenic COL4A3-5 variants is usually undertaken to investigate the cause of persistent hematuria, especially with a family history of hematuria or kidney function impairment. Alport syndrome experts now advocate genetic testing for persistent hematuria, even when a heterozygous pathogenic COL4A3 or COL4A4 is suspected, and cascade testing of their first-degree family members because of their risk of impaired kidney function. The experts recommend too that COL4A3 or COL4A4 heterozygotes do not act as kidney donors. Testing for variants in the COL4A3-COL4A5 genes should also be performed for persistent proteinuria and steroid-resistant nephrotic syndrome due to suspected inherited FSGS and for familial IgA glomerulonephritis and kidney failure of unknown cause., (Copyright © 2022 by the American Society of Nephrology.)

Alport syndrome is a genetic and hereditary disease, caused by mutations in the type IV collagen genes COL4A3 , COL4A4 and COL4A5 , that affects the glomerular basement membrane of the kidney. It is a rare disease with an underestimated prevalence. Genetic analysis of population cohorts has revealed that it is the second most common inherited kidney disease after polycystic kidney disease. Renal involvement is the main manifestation, although it may have associated extrarenal manifestations such as hearing loss or ocular problems. The degree of expression of the disease changes according to the gene affected and other factors, known or yet to be known. The pathophysiology is not yet fully understood, although some receptors, pathways or molecules are known to be linked to the disease. There is also no specific treatment for Alport syndrome; the most commonly used are renin-angiotensin-aldosterone system inhibitors. In recent years, diagnosis has come a long way, thanks to advances in DNA sequencing technologies such as next-generation sequencing (NGS). Further research at the genetic and molecular levels in the future will complete the partial vision of the pathophysiological mechanism that we have, and will allow us to better understand what is happening and how to solve it.

Background: Restless legs syndrome (RLS) is a common sleep-related movement disorder characterized by an urge to move the legs during inactivity, especially at evening-night. RLS is highly prevalent in patients with kidney failure and have an impact on quality of life, mood, sleep quality and overall on compliance to the dialysis. Alport syndrome (AS) is a rare inherited disease, predominantly X-linked, secondary to mutations in genes encoding α3, α4 or α5 chains of type IV collagen, and characterized by hematuria, chronic kidney disease, neurosensory deafness, and lenticonus., Case Presentation: Here we describe a family with a combination of X-linked AS and severe RLS accompanied by periodic limb movements during sleep (PLMS). In the first patient we identified, RLS was complicated by a paradoxical response to dopamine agonists named "augmentation", leading to sleep disruption, hallucinations and five peritoneal perforations during the peritoneal dialysis due to the difficulty to rest still. Therapeutic adjustments and renal transplantation improved RLS and PLMS. In two brothers, severe RLS prevented a compliance with hemodialysis. Female family members carrying the mutation were also affected by RLS, while those without the mutations were RLS-free., Conclusions: RLS has not been reported earlier in association with AS, but the peculiar combinations observed in this family will stimulate further clinical studies and motivate nephrologists to seek for RLS symptoms and sleep disturbances in AS patients.

The glomerular basement membrane is a vital component of the filtration barrier of the kidney and is primarily composed of a highly structured matrix of type IV collagen. Specific isoforms of type IV collagen, the α 3(IV), α 4(IV), and α 5(IV) isoforms, assemble into trimers that are required for normal glomerular basement membrane function. Disruption or alteration in these isoforms leads to breakdown of the glomerular basement membrane structure and function and can lead to progressive CKD known as Alport syndrome. However, there is wide variability in phenotype among patients with mutations affecting type IV collagen that depends on a complex interplay of sex, genotype, and X-chromosome inactivation. This article reviews the genetic basis of collagen disorders of the kidney as well as potential treatments for these conditions, including direct alteration of the DNA, RNA therapies, and manipulation of collagen proteins., (Copyright © 2021 by the American Society of Nephrology.)

Rationale: Renal artery pseudoaneurysm is a rare vascular lesion usually caused by trauma or percutaneous urological procedures. Spontaneous rupture of pseudoaneurysms without predisposing events, especially in hemodialysis patients, has rarely been reported., Patient Concerns: A 25-year-old man receiving maintenance hemodialysis visited the emergency room because of sudden severe right flank pain. He had no history of trauma or urological procedures except for a left renal biopsy to diagnose Alport syndrome 10 years prior., Diagnosis: Contrast-enhanced computed tomography revealed a right perirenal hematoma with pseudoaneurysms., Interventions: On renal angiography, multiple pseudoaneurysms were observed in the right renal artery branches and embolization was performed., Outcomes: Post-angiography showed no pseudoaneurysms. His abdominal pain improved, and he was discharged 2 weeks after embolization., Lessons: When maintenance dialysis patients complain of severe abdominal pain, spontaneous rupture of a renal pseudoaneurysm should be considered as a differential diagnosis, even if the patient has no history of trauma or previous urological procedures., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

There are currently no Food and Drug Administration-approved treatments for heart failure with preserved ejection fraction (HFpEF). Here we compared the effects of exercise with and without α/β-adrenergic blockade with carvedilol in Col4a3 -/- Alport mice, a model of the phenogroup 3 subclass of HFpEF with underlying renal dysfunction. Alport mice were assigned to the following groups: no treatment control ( n = 29), carvedilol ( n = 11), voluntary exercise ( n = 9), and combination carvedilol and exercise ( n = 8). Cardiac function was assessed by echocardiography after 4-wk treatments. Running activity of Alport mice was similar to wild types at 1 mo of age but markedly reduced at 2 mo (1.3 ± 0.40 vs. 4.5 ± 1.02 km/day, P < 0.05). There was a nonsignificant trend for increased running activity at 2 mo by carvedilol in the combination treatment group. Combination treatments conferred increased body weight of Col4a3 -/- mice (22.0 ± 1.18 vs. 17.8 ± 0.29 g in untreated mice, P < 0.01), suggesting improved physiology, and heart rates declined by similar increments in all carvedilol-treatment groups. The combination treatment improved systolic parameters; stroke volume (30.5 ± 1.99 vs. 17.8 ± 0.77 μL, P < 0.0001) as well as ejection fraction and global longitudinal strain compared with controls. Myocardial performance index was normalized by all interventions ( P < 0.0001). Elevated osteopontin plasma levels in control Alport mice were significantly lowered only by combination treatment, and renal function of the Alport group assessed by urine albumin creatinine ratio was significantly improved by all treatments. The results support synergistic roles for exercise and carvedilol to augment cardiac systolic function of Alport mice with moderately improved renal functions but no change in diastole. NEW & NOTEWORTHY In an Alport mouse model of heart failure with preserved ejection fraction (HFpEF), exercise and carvedilol synergistically improved systolic function without affecting diastole. Carvedilol alone or in combination with exercise also improved kidney function. Molecular analyses indicate that the observed improvements in cardiorenal functions were mediated at least in part by effects on serum osteopontin and related inflammatory cytokine cascades. The work presents new potential therapeutic targets and approaches for HFpEF.

In 2013, we published a set of clinical practice recommendations for the treatment of Alport syndrome in this journal. We recommended delaying the initiation of angiotensin-converting enzyme inhibition until the onset of overt proteinuria or, in some cases, microalbuminuria. Developments that have occurred over the past 7 years have prompted us to revise these recommendations. We now recommend the initiation of treatment at the time of diagnosis in males with X-linked Alport syndrome and in males and females with autosomal recessive Alport syndrome. We further recommend starting treatment at the onset of microalbuminuria in females with X-linked Alport syndrome and in males and females with autosomal dominant Alport syndrome. This article presents the rationale for these revisions as well as recommendations for diagnostic tactics intended to ensure the early diagnosis of Alport syndrome.

Alport syndrome is a genetically and phenotypically heterogeneous disorder of glomerular, cochlear, and ocular basement membranes resulting from mutations in the collagen IV genes COL4A3, COL4A4, and COL4A5. Alport syndrome can be transmitted as an X-linked, autosomal recessive, or autosomal dominant disorder. Individuals with Alport syndrome have a significant lifetime risk for kidney failure, as well as sensorineural deafness and ocular abnormalities. The availability of effective intervention for Alport syndrome-related kidney disease makes early diagnosis crucial, but this can be impeded by the genotypic and phenotypic complexity of the disorder. This review presents an approach to enhancing early diagnosis and achieving optimal outcomes., (Copyright © 2020 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Early initiation of therapy in patients with Alport syndrome (AS) slows down renal failure by many years. Genotype-phenotype correlations propose that the location and character of the individual's variant correlate with the renal outcome and any extra renal manifestations. In-depth clinical and genetic data of 60/62 children who participated in the EARLY PRO-TECT Alport trial were analyzed. Genetic variants were interpreted according to current guidelines and criteria. Genetically solved patients with X-linked inheritance were then classified according to the severity of their COL4A5 variant into less-severe, intermediate, and severe groups and disease progress was compared. Almost 90% of patients were found to carry (likely) pathogenic variants and classified as genetically solved cases. Patients in the less-severe group demonstrated a borderline significant difference in disease progress compared to those in the severe group (p = 0.05). While having only limited power according to its sample size, an obvious strength is the precise clinical and genetic data of this well ascertained cohort. As in published data differences in clinical progress were shown between patients with COL4A5 less-severe and severe variants. Therefore, clinical and segregational data are important for variant (re)classification. Genetic testing should be mandatory allowing early diagnosis and therapy of AS., (© 2020 The Authors. Clinical Genetics published by John Wiley & Sons Ltd.)

Currently, there are no treatments for Alport syndrome, which is the second most commonly inherited kidney disease. Here we report the development of an exon-skipping therapy using an antisense-oligonucleotide (ASO) for severe male X-linked Alport syndrome (XLAS). We targeted truncating variants in exon 21 of the COL4A5 gene and conducted a type IV collagen α3/α4/α5 chain triple helix formation assay, and in vitro and in vivo treatment efficacy evaluation. We show that exon skipping enabled trimer formation, leading to remarkable clinical and pathological improvements including expression of the α5 chain on glomerular and the tubular basement membrane. In addition, the survival period was clearly prolonged in the ASO treated mice group. This data suggests that exon skipping may represent a promising therapeutic approach for treating severe male XLAS cases.

Alport syndrome is caused by mutations in the genes COL4A3, COL4A4 or COL4A5 and is characterised by progressive glomerular disease, sensorineural hearing loss and ocular defects. Occurring in less than 1:5000, Alport syndrome is a rare genetic disorder but still accounts for > 1% of the prevalent population receiving renal replacement therapy. There is also increasing awareness about the risk of chronic kidney disease in individuals with heterozygous mutations in Alport syndrome genes. The mainstay of current therapy is the use of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, yet potential new therapies are now entering clinical trials. The 2017 International Workshop on Alport Syndrome in Glasgow was a pre-conference workshop ahead of the 50th anniversary meeting of the European Society for Pediatric Nephrology. It focussed on updates in clinical practice, genetics and basic science and also incorporated patient perspectives. More than 80 international experts including clinicians, geneticists, researchers from academia and industry, and patient representatives took part in panel discussions and breakout groups. This report summarises the workshop proceedings and the relevant contemporary literature. It highlights the unique clinician, patient and researcher collaborations achieved by regular engagement between the groups.

Alport syndrome (AS) is an inherited genetic disorder characterized by range of alterations from glomerular basement membrane abnormalities up to end-stage renal disease. Pathogenic variants in the collagen α3, α4, and α5 encoding genes are causative both of the autosomal dominant and of the X-linked forms of AS. Podocytes are the only renal cells that are able to produce the COL(IV)a3-a4a5 heterotrimer. We have previously demonstrated how it is possible to isolate podocyte-lineage cells from urine of patients, providing an easily accessible cellular model closer to the podocytes' physiological conditions. Taking advantage of disease-relevant cell lines, we employed a two-plasmid approach in order to achieve a beneficial and stable variant-specific correction using CRISPR/Cas9 genome editing. One plasmid carries a Donor DNA and a reporter system mCherry/GFP to track the activity of Cas9 in cells. The other plasmid carries a self-cleaving SpCas9 and the variant-specific sgRNA. We have analyzed two stable podocyte-lineage cell lines, harboring a variant in the X-linked COL4A5 (p.(Gly624Asp)) and in the autosomal COL4A3 gene (p.(Gly856Glu)). We have achieved reversion of variants greater than 40% with undesired insertions/deletions lower than 15%. Overall, we have demonstrated a new gene therapy approach directly on patients' cells, key players of Alport pathogenesis, and we have reverted COL4 causative variants towards the wild type state. These results, in combination with preclinical models, could open new frontiers in the management and the treatment of the disorder.

Alport syndrome (AS) is the most frequent inherited kidney disease after autosomal dominant polycystic kidney disease. It has three different patterns of inheritance-autosomal dominant, autosomal recessive and X-linked-which in part explains the wide spectrum of disease, ranging from isolated microhaematuria to end-stage renal disease early in life. The search for a treatment for AS is being pursued vigorously, not only because of the obvious unmet need but also because AS is a rare disease and any drug approved will have an orphan drug designation with its various benefits. Moreover, AS patients are quite young with very few comorbidities, which facilitates clinical trials. This review identifies the particularities of each pattern of inheritance but focuses mainly on new drugs or therapeutic targets for the disease. Most treatment-related investigations are directed not at the main abnormality in AS, namely collagen IV composition, but rather at the associated inflammation and fibrosis. Thus, AS may serve as a proof of concept for numerous drugs of potential value in many diseases that cause chronic kidney disease., (© The Author(s) 2019. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.)

The glomerular basement membrane (GBM) is a critical component of the kidney's blood filtration barrier. Alport syndrome, a hereditary disease leading to kidney failure, is caused by the loss or dysfunction of the GBM's major collagen type IV (COL4) isoform α 3 α 4 α 5 . The constituent COL4 α-chains assemble into heterotrimers in the endoplasmic reticulum before secretion into the extracellular space. If any one of the α 3 -, α 4 -, or α 5 -chains is lost due to mutation of one of the genes, then the entire heterotrimer is lost. Patients with Alport syndrome typically have mutations in the X-linked COL4A5 gene or uncommonly have the autosomal recessive form of the disease due to COL4A3 or COL4A4 mutations. Treatment for Alport syndrome is currently limited to angiotensin-converting enzyme inhibition or angiotensin receptor blockers. Experimental approaches in Alport mice have demonstrated that induced expression of COL4A3, either widely or specifically in podocytes of Col4a3 -/- mice, can abrogate disease progression even after establishment of the abnormal GBM. While targeting podocytes in vivo for gene therapy is a significant challenge, the more accessible glomerular endothelium could be amenable for mutant gene repair. In the present study, we expressed COL4A3 in Col4a3 -/- Alport mice using an endothelial cell-specific inducible transgenic system, but collagen-α 3 α 4 α 5 (IV) was not detected in the GBM or elsewhere, and the Alport phenotype was not rescued. Our results suggest that endothelial cells do not express the Col4a3/a4/a5 genes and should not be viewed as a target for gene therapy.

Alport syndrome (AS) is a progressive hereditary renal disease that is characterized by sensorineural hearing loss and ocular abnormalities. It is divided into three modes of inheritance, namely, X-linked Alport syndrome (XLAS), autosomal recessive AS (ARAS), and autosomal dominant AS (ADAS). XLAS is caused by pathogenic variants in COL4A5, while ADAS and ARAS are caused by those in COL4A3/COL4A4. Diagnosis is conventionally made pathologically, but recent advances in comprehensive genetic analysis have enabled genetic testing to be performed for the diagnosis of AS as first-line diagnosis. Because of these advances, substantial information about the genetics of AS has been obtained and the genetic background of this disease has been revealed, including genotype-phenotype correlations and mechanisms of onset in some male XLAS cases that lead to milder phenotypes of late-onset end-stage renal disease (ESRD). There is currently no radical therapy for AS and treatment is only performed to delay progression to ESRD using nephron-protective drugs. Angiotensin-converting enzyme inhibitors can remarkably delay the development of ESRD. Recently, some new drugs for this disease have entered clinical trials or been developed in laboratories. In this article, we review the diagnostic strategy, genotype-phenotype correlation, mechanisms of onset of milder phenotypes, and treatment of AS, among others.

The occurrence of pregnancy in a patient with alport syndrome is rare because this renal disease can impact fertility. We report a case of alport syndrome associated with pregnancy in a parturient woman aged 28 years. Possible premature delivery associated with elevated blood pressure led to hospitalization for patient's mangement. We here report a literature review on the various maternal-foetal complications of alport syndrome and we focus on the management of alport syndrome during pregnancy., Competing Interests: Les auteurs ne déclarent aucun conflit d'intérêts.

Alport syndrome is a hereditary glomerular basement membrane disease caused by mutations in the COL4A3/4/5 genes encoding the type IV collagen alpha 3-5 chains. Most cases of Alport syndrome are inherited as X-linked dominant, and some as autosomal recessive or autosomal dominant. The primary manifestations are hematuria, proteinuria, and progressive renal failure, whereas some patients present with sensorineural hearing loss and ocular abnormalities. Renin-angiotensin-aldosterone system blockade is proven to delay the onset of renal failure by reducing proteinuria. Renal transplantation is a curative treatment for patients who have progressed to end-stage renal disease. However, only supportive measures can be used to improve hearing loss and visual loss. Although both stem cell therapy and gene therapy aim to repair the basement membrane defects, technical difficulties require more research in Alport mice before clinical studies. Here, we review the renal, auricular, and ocular manifestations and outcomes of Alport syndrome and their current management.

Mutations in the genes COL4A3, COL4A4, and COL4A5 affect the synthesis, assembly, deposition, or function of the collagen IV α345 molecule, the major collagenous constituent of the mature mammalian glomerular basement membrane. These mutations are associated with a spectrum of nephropathy, from microscopic hematuria to progressive renal disease leading to ESRD, and with extrarenal manifestations such as sensorineural deafness and ocular anomalies. The existing nomenclature for these conditions is confusing and can delay institution of appropriate nephroprotective therapy. Herein we propose a new classification of genetic disorders of the collagen IV α345 molecule with the goal of improving renal outcomes through regular monitoring and early treatment., (Copyright © 2018 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

Alport Syndrome (ATS) is a rare genetic disorder caused by collagen IV genes mutations, leading to glomerular basement membrane damage up to end-stage renal disease. Podocytes, the main component of the glomerular structure, are the only cells able to produce all the three collagens IV alpha chains associated with ATS and thus, they are key players in ATS pathogenesis. However, podocytes-targeted therapeutic strategies have been hampered by the difficulty of non-invasively isolating them and transcripts-based diagnostic approaches are complicated by the inaccessibility of other COL4 chains-expressing cells. We firstly isolated podocyte-lineage cells from ATS patients' urine samples, in a non-invasive way. RT-PCR analysis revealed COL4A3, COL4A4, and COL4A5 expression. Transcripts analysis on RNA extracted from patient's urine derived podocyte-lineage cells allowed defining the pathogenic role of intronic variants, namely one mutation in COL4A3 (c.3882+5G>A), three mutations in COL4A4 (c.1623+2T>A, c.3699&#95;3706+1del, c.2545+143T>A), and one mutation in COL4A5 (c.3454+2T>C). Therefore, our cellular model represents a novel tool, essential to unequivocally prove the effect of spliceogenic intronic variants on transcripts expressed exclusively at a glomerular level. This process is a key step for providing the patient with a definite molecular diagnosis and with a proper recurrence risk. The established system also opens up the possibility of testing personalized therapeutic approaches on disease-relevant cells., (© 2017 Wiley Periodicals, Inc.)

Alport syndrome (AS) is a genetic disease characterized by haematuric glomerulopathy variably associated with hearing loss and anterior lenticonus. It is caused by mutations in the COL4A3, COL4A4 or COL4A5 genes encoding the α3α4α5(IV) collagen heterotrimer. AS is rare, but it accounts for >1% of patients receiving renal replacement therapy. Angiotensin-converting enzyme inhibition slows, but does not stop, the progression to renal failure; therefore, there is an urgent requirement to expand and intensify research towards discovering new therapeutic targets and new therapies. The 2015 International Workshop on Alport Syndrome targeted unmet needs in basic science, genetics and diagnosis, clinical research and current clinical care. In three intensive days, more than 100 international experts including physicians, geneticists, researchers from academia and industry, and patient representatives from all over the world participated in panel discussions and breakout groups. This report summarizes the most important priority areas including (i) understanding the crucial role of podocyte protection and regeneration, (ii) targeting mutations by new molecular techniques for new animal models and potential gene therapy, (iii) creating optimal interaction between nephrologists and geneticists for early diagnosis, (iv) establishing standards for mutation screening and databases, (v) improving widespread accessibility to current standards of clinical care, (vi) improving collaboration with the pharmaceutical/biotech industry to investigate new therapies, (vii) research in hearing loss as a huge unmet need in Alport patients and (viii) the need to evaluate the risk and benefit of novel (including 'repurposing') therapies on an international basis., (© The Author 2016. Published by Oxford University Press on behalf of ERAEDTA.)

Background: Alport syndrome and ANCA-associated vasculitis are both rare diseases. The co-existence of these two conditions has never been reported. There is no obvious pathogenic link between these two glomerular diseases. The management of this case highlights the importance of a systematic approach when investigating the unexpected unfavourable evolution of a known glomerulopathy., Case Presentation: A-17 year old caucasian boy with a genetically proven X-linked Alport syndrome presented with progressive dyspnea, fatigue and pallor. His blood tests showed a severe anemia (Hb 6.9 g/dl) with acute worsening of kidney function (serum creatinine, normal 9 months earlier, was now 3.6 mg/dl). Microscopic hematuria and proteinuria also worsened. He soon developed signs of alveolar hemorrhage. Serological tests showed the presence of perinuclear ANCA with anti MPO specificity. Kidney biopsy showed a necrotizing and crescentic glomerulonephritis. Pulses of methylprednisolone were given in combination with plasmapheresis. The patient further received 6 pulses of cyclophosphamide, followed by maintenance oral azathioprine. During the 15-months follow up he remained well with serum creatinine back to normal, and some residual proteinuria and hematuria ascribed to Alport syndrome., Conclusion: We report a young patient with the coexistence of Alport syndrome and ANCA associated vasculitis. Clinicians should be aware of the possibility of a second acquired disease in a patient with a known kidney disease, genetic in this case. This coexistence is very rare, but should be considered even if both diseases are rare, if the evolution is atypical for the single (known) primary disease. The diagnosis of the added vasculitis prompted in our case the initiation of immunosuppressive drugs, with a favourable outcome.

The most frequent cause of familial glomerular hematuria is thin basement membrane nephropathy (TBMN) caused by germline COL4A3 or COL4A4 gene mutations. Less frequent but important cause with respect to morbidity is Alport syndrome caused by germline COL4A5 gene mutations. The features of Alport syndrome include hematuria, proteinuria and all males with X-linked disease and all individuals with recessive disease will develop end stage renal disease, usually at early youth. In X-linked Alport syndrome, a clear genotype-phenotype correlation is typically observed in men. Deleterious COL4A5 mutations are associated with a more severe renal phenotype and more frequent high-frequency sensorineural hearing loss and ocular abnormalities. Less severe COL4A5 mutations result in a milder phenotype, with less frequent and later onset extrarenal anomalies. The phenotype in females is highly variable, mostly due to inactivation of one of the X chromosomes. Isolated cases may be caused by de novo COL4A5 mutations or by gonosomal mosaicism. Untreated autosomal recessive Alport syndrome, caused by COL4A3 and COL4A4 mutations, is typically associated with ESRD at the age of 23-25 years and extrarenal symptoms in both men and women. The TBMN phenotype is associated with heterozygous carriers of COL4A3, COL4A4 mutations. Molecular genetic testing is the gold standard for diagnosing these diseases. Although genotype-phenotype correlations exist, the phenotype is influenced by modifying factors, which remain mainly undefined. No therapy is available that targets the cause of Alport syndrome; angiotensin-converting enzyme inhibitor therapy delays renal failure and improves lifespan., (Copyright © 2017 The Lithuanian University of Health Sciences. Production and hosting by Elsevier Sp. z o.o. All rights reserved.)

Pentraxin-2 (PTX-2), also known as serum amyloid P component (SAP/APCS), is a constitutive, antiinflammatory, innate immune plasma protein whose circulating level is decreased in chronic human fibrotic diseases. Here we show that recombinant human PTX-2 (rhPTX-2) retards progression of chronic kidney disease in Col4a3 mutant mice with Alport syndrome, reducing blood markers of kidney failure, enhancing lifespan by 20%, and improving histological signs of disease. Exogenously delivered rhPTX-2 was detected in macrophages but also in tubular epithelial cells, where it counteracted macrophage activation and was cytoprotective for the epithelium. Computational analysis of genes regulated by rhPTX-2 identified the transcriptional regulator c-Jun along with its activator protein-1 (AP-1) binding partners as a central target for the function of rhPTX-2. Accordingly, PTX-2 attenuates c-Jun and AP-1 activity, and reduces expression of AP-1-dependent inflammatory genes in both monocytes and epithelium. Our studies therefore identify rhPTX-2 as a potential therapy for chronic fibrotic disease of the kidney and an important inhibitor of pathological c-Jun signaling in this setting., Competing Interests: R.M. Jack is the CSO, COO, and President of Promedior Inc. M.L. Lupher Jr. is a former member of Promedior Inc. J.S. Duffield holds stock options in Promedior Inc.

Objective: To investigate the clinical characteristics and the status of diagnosis and treatment of patients with Alport syndrome in China., Method: Patients with affirmative diagnosis of Alport syndrome from Department of Pedatrics, Peking University First Hospital in the past 20 years (1995-2015) were analyzed retrospectively. The clinical data including initial symptoms, visit reasons, age at onset of disease, family history, hereditary mode, methods of diagnosis, misdiagnosis and mistreatment were collected., Result: A total of 398 patients with Alport syndrome were included in this study, 48.2% of patients had the onset of symptoms before age of 3 years. The rate of onset of symptoms and diagnosis before age of 17 years were 95.7%. The initial symptoms included gross hematuria (37.2%), microscopic hematuria and proteinuria (25.1%), microscopic hematuria (14.8%), edema of eyelid and lower limbs (10.3%), increased foam in urine (4.3%), etc.; 39.5% of patients had no symptoms of urinary tract. Only 14.0% of the patients were diagnosed as Alport syndrome for the first time, and 86.0% of the patients were misdiagnosed. Hormones and immunosuppressive agents were used in 19.0% of patients diagnosed as Alport syndrome, and in 43.0% of patients there was misdiagnosis. Skin biopsy and immunofluorescence of type Ⅳ collagen ɑ5 chain in epithelial basement membrane had a detection rate of 77.8%. Electron microscopy of glomerular basement membrane had a detection rate of 92.6%, and genetic testing 96.6%. The time interval of diagnosis was 18.2 months and was gradually shortened in recent years., Conclusion: Alport syndrome developed at a very young age. Hematuria was the most frequent initial symptom. There was a high rate of misdiagnosis and mistreatment for Alport syndrome. Genetic testing for Alport syndrome had advantages of high detection rate, genetic consultation and prenatal diagnosis.

Alport syndrome (AS) is a hereditary glomerulopathy caused by a mutation in type IV collagen genes, which disrupts glomerular basement membrane, leading to progressive glomerulosclerosis and end-stage renal failure. There is at present no cure for AS, and cell-based therapies offer promise to improve renal function. In this study, we found that human first trimester fetal chorionic stem cells (CSC) are able to migrate to glomeruli and differentiate down the podocyte lineage in vitro and in vivo. When transplanted into 7-week-old Alport 129Sv-Col4α3(tm1Dec)/J (-/-) mice, a single intraperitoneal injection of CSC significantly lowered blood urea and urine proteinuria levels over the ensuing 2 weeks. In addition, nearly two-thirds of transplanted -/- mice maintained their weight above the 80% welfare threshold, with both males and females weighing more than age-matched nontransplanted -/- mice. This was associated with less renal cortical fibrosis and interstitial inflammation compared to nontransplanted mice as shown by reduction in murine CD4, CD68, and CD45.2 cells. Transplanted CSC homed to glomeruli, where they expressed CR1, VEGFA, SYNAPTOPODIN, CD2AP, and PODOCIN at the RNA level and produced PODOCIN, CD2AP, and COLIVα3 proteins in nontransplanted -/- mice, indicating that CSC have adopted a podocyte phenotype. Together, these data indicate that CSC may be used to delay progression of renal pathology by a combination of anti-inflammatory effects and replacement of the defective resident podocytes.

Alport syndrome is an inherited disease characterized by progressive renal failure, hearing loss, and ocular abnormalities. Mutations in the COL4A5 (X-linked), or COL4A3 and COL4A4 (autosomal recessive) genes result in absence of the collagen IV α3α4α5 network from the basement membranes of the cornea, lens capsule, and retina and are associated with corneal opacities, anterior lenticonus, fleck retinopathy, and temporal retinal thinning. Typically, these features do not affect vision or, in the case of lenticonus, are correctable. In contrast, the rarer ophthalmic complications of posterior polymorphous corneal dystrophy, giant macular hole, and maculopathy all produce visual loss. Many of the ocular features of Alport syndrome are common, easily recognizable, and thus, helpful diagnostically, and in identifying the likelihood of early-onset renal failure. Lenticonus and central fleck retinopathy strongly suggest the diagnosis of Alport syndrome and are associated with renal failure before the age of 30 years, in males with X-linked disease. Sometimes, ophthalmic features suggest the mode of inheritance. A peripheral retinopathy in the mother of a male with hematuria suggests X-linked inheritance, and central retinopathy or lenticonus in a female means that recessive disease is likely. Ocular examination, retinal photography, and optical coherence tomography are widely available, safe, fast, inexpensive, and acceptable to patients. Ocular examination is particularly helpful in the diagnosis of Alport syndrome when genetic testing is not readily available or the results are inconclusive. It also detects complications, such as macular hole, for which new treatments are emerging., (Copyright © 2015 by the American Society of Nephrology.)

MicroRNA-21 (miR-21) contributes to the pathogenesis of fibrogenic diseases in multiple organs, including the kidneys, potentially by silencing metabolic pathways that are critical for cellular ATP generation, ROS production, and inflammatory signaling. Here, we developed highly specific oligonucleotides that distribute to the kidney and inhibit miR-21 function when administered subcutaneously and evaluated the therapeutic potential of these anti-miR-21 oligonucleotides in chronic kidney disease. In a murine model of Alport nephropathy, miR-21 silencing did not produce any adverse effects and resulted in substantially milder kidney disease, with minimal albuminuria and dysfunction, compared with vehicle-treated mice. miR-21 silencing dramatically improved survival of Alport mice and reduced histological end points, including glomerulosclerosis, interstitial fibrosis, tubular injury, and inflammation. Anti-miR-21 enhanced PPARα/retinoid X receptor (PPARα/RXR) activity and downstream signaling pathways in glomerular, tubular, and interstitial cells. Moreover, miR-21 silencing enhanced mitochondrial function, which reduced mitochondrial ROS production and thus preserved tubular functions. Inhibition of miR-21 was protective against TGF-β-induced fibrogenesis and inflammation in glomerular and interstitial cells, likely as the result of enhanced PPARα/RXR activity and improved mitochondrial function. Together, these results demonstrate that inhibition of miR-21 represents a potential therapeutic strategy for chronic kidney diseases including Alport nephropathy.

The glomerular filtration barrier comprises a fenestrated capillary endothelium, glomerular basement membrane and podocyte slit diaphragm. Over the past decade we have come to realise that permselectivity depends on size and not necessarily charge, that the molecular sieve depends on the podocyte contractile apparatus and is highly dynamic, and that protein uptake by proximal tubular epithelial cells stimulates signalling and the production of transcription factors and inflammatory mediators. Alport syndrome is the second commonest monogenic cause of renal failure after autosomal dominant polycystic kidney disease. Eighty per cent of patients have X-linked disease caused by mutations in the COL4A5 gene. Most of these result in the replacement of the collagen IV α3α4α5 network with the α1α1α2 heterotrimer. Affected membranes also have ectopic laminin and increased matrix metalloproteinase levels, which makes them more susceptible to proteolysis. Mechanical stress, due to the less elastic membrane and hypertension, interferes with integrin-mediated podocyte-GBM adhesion. Proteinuria occurs when urinary levels exceed tubular reabsorption rates, and initiates tubulointerstitial fibrosis. The glomerular mesangial cells produce increased TGFβ and CTGF which also contribute to glomerulosclerosis. Currently there is no specific therapy for Alport syndrome. However treatment with angiotensin converting enzyme (ACE) inhibitors delays renal failure progression by reducing intraglomerular hypertension, proteinuria, and fibrosis. Our greater understanding of the mechanisms underlying the GBM changes and their consequences in Alport syndrome have provided us with further novel therapeutic targets., (© 2014 The Authors. The Journal of Physiology © 2014 The Physiological Society.)

The hereditary type IV collagen disease Alport syndrome (AS) always leads to end-stage renal failure. Yesterday, for the past 90 years, this course was described as 'inevitable'. Today, RAAS blockade has changed the 'inevitable' course to a treatable disease. Tomorrow, researchers hope to erase the 'always' from 'always leads to renal failure' in the textbooks. This review elucidates therapeutic targets that evolve from research: (i) kidney embryogenesis and pathogenesis; (ii) phenotype-genotype correlation and the role of collagen receptors and podocytes; (iii) the malfunctioning Alport-GBM; (iv) tubulointerstitial fibrosis; (v) the role of proteinuria in pathogenesis and prognosis; and (vi) secondary events such as infections, hyperparathyroidism and hypercholesterolaemia. Therefore, moderate lifestyle, therapy of bacterial infections, Paricalcitol in adult patients with hyperparathyroidism and HMG-CoA-reductase inhibitors in adult patients with dyslipoproteinemia might contribute to a slower progression of AS and less cardiovascular events. In the future, upcoming treatments including stem cells, chaperon therapy, collagen receptor blockade and anti-microRNA therapy will expand our perspective in protecting the kidneys of Alport patients from further damage. This perspective on current and future therapies is naturally limited by our personal focus in research, but aims to motivate young scientists and clinicians to find a multimodal cure for AS., (© The Author 2014. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.)