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Introduction: This study aimed to analyze the clinical characteristics of nephropathy associated with WT1 gene mutations in Chinese children and explore the relationship between genotype and clinical phenotype. Methods: Cases diagnosed at the Guangzhou Women and Children's Medical Center, were combined with those retrieved from PubMed and China National Knowledge Infrastructure (CNKI) databases from January 2015 to June 2022 and integrated into a study cohort; grouped according to gene mutation sites, clinical phenotype, and renal pathological types. The clinical characteristics between groups were compared, and the relationship between genotype and age of onset, clinical phenotype, and pathological type were retrospectively analyzed. Results: The center enrolled 15 confirmed children: seven cases of non-simple nephropathy, including Denys-Drash syndrome (DDS) and Frasier syndrome (FS); eight cases of isolated steroid-resistant nephrotic syndrome (ISRNS); and 13 cases (86.7%) that progressed to end-stage renal disease (ESRD). The initial hemoglobin and bicarbonate levels of patients with clinical non-simple nephropathy were significantly lower than those with simple nephropathy, whereas the serum creatinine levels were higher than those of patients with simple nephropathy. A total of 75 cases of nephropathy associated with WT1 mutations in the study cohort met the inclusion and exclusion criteria. The most common clinical manifestations of WT1 mutations in this cohort were DDS (29/75, 38.7%) and ISRNS (37/75, 49.3%). A renal biopsy was performed in 43 patients, and the common types of renal pathology were focal segmental glomerulosclerosis (23/43, 53.5%) and DMS (13/43, 30.2%). Within the cohort, there were 12 cases (16.0%) in the exon 8 mutation group, 32 (42.6%) in the exon 9 group, 19 (25.3%) in the intron 9 group, and 12 (16.0%) in other gene site mutation groups. Common sites of WT1 mutations in Chinese children were exons 9 and intron 9. Exon 8 mutations were uniquely correlated with the age of onset within three months [5/7; 71.4%; Adjusted standardized residual (AR) = 4.2]. The renal survival time in the exon 8 mutation group was the shortest (P = 0.003). Discussion: The molecular and biological characteristics of WT1 mutation-related nephropathy determine the clinical type, pathological features, and renal survival time of the disease; and there was a strong correlation between the genotype and clinical phenotype.

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Specialized centers are needed for nephrology and urology care of children. The justifications are the specialized nature of care needed and the growing incidence and prevalence. Children with chronic kidney disease (CKD) are at risk of morbidity, mortality, and decreased quality of life. Current pediatric practice structures are apparently poorly suited for the increasing demands of chronic disease in children. Kidney diseases account for around 8%-10% of total outpatients and 12% of admissions to the pediatric ward in hospitals. The major causes of pediatric CKD in registries are congenital anomalies of the kidney and urinary tract (around 50%), followed by inherited nephropathies and glomerulonephritis. The nephrologist's role is important for specialized investigations and treatment. Urologist's services are essential for the wide variety of conditions from birth to early adult age for complete cure and complementing medical management. Children have a right to treatments and to resources that are as sophisticated and advanced as those available to adults. Simple and sophisticated care for all children with ailments of the kidneys and related structures is important for ensuring 'health for all'. The availability of 'Child Kidney Care Centers' will go a long way in improving the lives of affected children.

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Lipoprotein glomerulopathy (LPG) is a rare autosomal dominant kidney disease caused by pathogenic mutations in the APOE gene. Collagen type III glomerulopathy (CG) is a sporadic condition in adults characterized by abnormal accumulation of type III collagen in the subendothelial space and mesangium of the glomerulus. We report the first case of both LPG and CG in a 21-year-old male. A search of the literature found no confirmed reports of these two concomitant nephropathies. The patient presented with hypertension, proteinuria, hematuria and hyperlipidemia. Renal pathology showed lipid vacuoles in the enlarged glomerular capillary loops and type III collagen in the segmental mesangial area and on the inner side of the glomerular basement membrane by electron microscopy. Whole-exome sequencing revealed a heterozygous mutation (c.127C>T; p. Arg43Cys) in exon 3 of the APOE gene, known as the APOE-Kyoto of LPG. In addition, two heterozygous COL4A4 mutations (c.4715C>T in exon 47 and c.5065 T>C in exon 48) were observed, the first one was suspected pathogenic and the other one was uncertain significant. There is no special treatment for these diseases. The patient was treated with lipid-lowering agents, renin-angiotensin-aldosterone system inhibition and tripterygium glycosides. The patient received double-filtration plasmapheresis and immunoadsorption therapy when renal function deteriorated dramatically. Immunoadsorption was beneficial for this patient.

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Alport syndrome(AS)is a hereditary nephropathy associated with hematuria, proteinuria and progressive kidney failure.It is characterized by a defective glomerular basement membrane caused by mutations in type Ⅳ collagen genes COL4A3/A4/A5, which result in defective in the type Ⅳa3, a4 and a5 chains respectively.At present, there is no preventive or curative therapies for AS.Inhibitors of the renin angiotensin aldosterone system are routinely used to slow the progression of kidney disease and prolong life expectancy.Ramipril was found in retrospective studies to delay the onset of end stage renal disease(ESRD), supporting that early initiation of renin angiotensin aldosterone system blockade is very important.Advances in our understanding on the pathogenesis of AS has culminated in the development of innovative therapeutic approaches that are currently under investigation.This review will briefly outline novel therapeutic targets for the prevention of renal disease progression in AS.

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The paper reports a case of coenzyme Q10 deficiency nephrotic syndrome associated with coenzyme Q2 gene mutation and reviews the literature on this topic. The patient presented with hematuria, proteinuria, and a diminution of vision as clinical manifestations. But the proteinuria was not relieved after sufficient doses of glucocorticoids for over 2 months. The patient′s birth history was unremarkable, and his parents were both healthy and not consanguineous. Whole exome sequencing revealed that the patient had a mutation of coenzyme Q2 gene at c.973A>G(p.T325A) and c.517C>T(p.R173C). Combined with renal biopsy pathology, the patient was diagnosed with hereditary nephropathy and started the supplements of coenzyme Q10 after stopping glucocorticoid treatments immediately. After 5 weeks of therapy, the patient′s 24-h urine protein quantification decreased from 6.01 g to 1.53 g.

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The Monocyte chemoattractant protein-1 (MCP-1), also referred to as chemokine ligand 2 (CCL2), belongs to the extensive chemokine family and serves as a crucial mediator of innate immunity and tissue inflammation. It has a notable impact on inflammatory conditions affecting the kidneys. Upon binding to its receptor, MCP-1 can induce lymphocytes and NK cells' homing, migration, activation, differentiation, and development while promoting monocytes' and macrophages' infiltration, thereby facilitating kidney disease-related inflammation. As a biomarker for kidney disease, MCP-1 has made notable advancements in primary kidney diseases such as crescentic glomerulonephritis, chronic glomerulonephritis, primary glomerulopathy, idiopathic proteinuria glomerulopathy, acute kidney injury; secondary kidney diseases like diabetic nephropathy and lupus nephritis; hereditary kidney diseases including autosomal dominant polycystic kidney disease and sickle cell kidney disease. MCP-1 not only predicts the occurrence, progression, prognosis of the disease but is also closely associated with the severity and stage of nephropathy. When renal tissue is stimulated or experiences significant damage, the expression of MCP-1 increases, demonstrating a direct correlation with the severity of renal injury.

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Background: Chronic kidney disease (CKD) in childhood and adolescence occurs with a median incidence of 9 per million of the age-related population. Over 70% of CKD cases under the age of 25 years can be attributed to a hereditary kidney disease. Among these are hereditary podocytopathies, ciliopathies and (monogenic) congenital anomalies of the kidney and urinary tract (CAKUT). These disease entities can present with a vast variety of extrarenal manifestations. So far, skeletal anomalies (SA) have been infrequently described as extrarenal manifestation in these entities. The aim of this study was to retrospectively investigate a cohort of individuals with hereditary podocytopathies, ciliopathies or CAKUT, in which molecular genetic testing had been performed, for the extrarenal manifestation of SA. Material and Methods: A cohort of 65 unrelated individuals with a clinically presumed hereditary podocytopathy (focal segmental glomerulosclerosis, steroid resistant nephrotic syndrome), ciliopathy (nephronophthisis, Bardet-Biedl syndrome, autosomal recessive/dominant polycystic kidney disease), or CAKUT was screened for SA. Data was acquired using a standardized questionnaire and medical reports. 57/65 (88%) of the index cases were analyzed using exome sequencing (ES). Results: 8/65 (12%) index individuals presented with a hereditary podocytopathy, ciliopathy, or CAKUT and an additional skeletal phenotype. In 5/8 families (63%), pathogenic variants in known disease-associated genes (1x BBS1, 1x MAFB, 2x PBX1, 1x SIX2) could be identified. Conclusions: This study highlights the genetic heterogeneity and clinical variability of hereditary nephropathies in respect of skeletal anomalies as extrarenal manifestation.

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A 69-year-old woman presented with mild renal dysfunction, proteinuria, and sensorineural hearing loss. A renal biopsy showed focal segmental glomerulosclerosis with thinning of the glomerular basement membrane. There was a positive family history of end-stage kidney disease and hearing loss. Although Alport syndrome was suspected from these features, a genetic test using next-generation sequencer identified a novel missense mutation in LMX1B, c.655C>G: p. (Pro219Ala). In silico analyses predicted the pathogenicity of the mutation. Thus, the present case was diagnosed as LMX1B-associated nephropathy presenting with Alport syndrome-like phenotype, expanding the disease spectrum of LMX1B nephropathy.

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Hereditary nephropathy is a primary progressive glomerular disease in dogs associated with the c.115A>T mutation in the COL4A4 gene in English cocker spaniel (ECS) dogs. The disease is inherited in an autosomal recessive manner. Hereditary nephropathy has been described in this breed since the late 1940s. To date, there are no data on the prevalence of this disease in Brazil, so the aim of this study was to evaluate the allelic frequency of this mutation in ECS dogs in this country. The DNA samples were purified from blood samples or buccal swabs from 221 ECS dogs. Fragments of the DNA containing the mutation were amplified by PCR and submitted to direct gene sequencing. The allele frequency of the mutation was 0.9%. The presence of the mutation in the ECS dog population in Brazil reveals the importance of performing the genotyping tests in these dogs as a method of diagnosing the disease and identifying heterozygous animals, aiming to reduce clinical cases of disease through mating.

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C4d positive glomerulopathies with pseudolinear capillary wall deposits caused by basement membrane (GBM) remodeling have sporadically been reported in renal transplants. Here we describe the case of a hypertensive 60 year-old male with a 5 month history of nephrotic range proteinuria in the setting of normal serum creatinine, complement and ANA levels. Work-up showed MGUS (IgG/kappa restricted). A diagnostic renal biopsy to search for monoclonal gammopathy of renal significance demonstrated thickened glomerular capillary walls with strong pseudolinear complement factor C4d deposits by immunofluorescence microscopy (IF); all other IF studies including stains for Col4A3 were unrevealing with only minor abnormalities seen for Col4A5. The strong and unusual C4d staining of undetermined direct diagnostic significance triggered additional electron microscopic studies uncovering marked structural GBM changes suggestive of a hereditary nephropathy. Further genetic testing revealed a very rare X-linked single missense mutation in the NC1 domain of Col4A5 (exon 51) with a single amino acid substitution (COL4A5 p.A1581S) that has thus far not been reported in hereditary nephropathies. Our case provides further support for pseudolinear glomerular C4d deposits as general markers of GBM remodeling, in our case an unexpected hereditary nephropathy in an older male. Pseudolinear C4d: a general signpost for architectural GBM disturbance and a stimulus for in-depth studies including electron microscopy.

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BACKGROUND: MYH9-related diseases (MYH9-RD) are autosomal dominant disorders caused by mutations of the MYH9 gene encoding the non-muscle myosin heavy chain IIA. They are characterized by congenital thrombocytopenia, giant platelets and leucocyte inclusions. Hearing impairment, pre-senile cataract and nephropathy can also occur. We aimed to evaluate renal involvement and outcome in MYH9-RD patients followed-up by nephrologists. METHODS: We conducted a retrospective multicentre observational study of 13 patients among 9 families with MYH9 mutation diagnosed by genetic testing and immunofluorescence assay referred to nephrologists. RESULTS: At initial referral, median age was 30 (range 14-76) years. Median estimated glomerular filtration rate was 66 mL/min/1.73 m2 (0-141) and two patients had already end-stage renal disease (ESRD). Renal presentation associated proteinuria (n = 12), haematuria (n = 6) and hypertension (n = 6). Three patients developed a rapid onset ESRD whereas five others had a relatively stable kidney function over a 3-year median follow-up (1-34). Extra-renal features varied widely, with hearing impairment in six patients, cataract in two and mild liver dysfunction in seven. Thrombocytopenia existed at referral in 11 patients. Time to diagnosis varied from 0 to 29 years (median 3 years). Initial diagnoses such as idiopathic thrombocytopenic purpura (n = 4) and focal segmental glomerulosclerosis (n = 1) led to corticosteroid administration (n = 4), intravenous immunoglobulins (n = 3), cyclophosphamide (n = 1) and splenectomy (n = 1). CONCLUSIONS: Renal involvement and outcome in MYH9-RD are heterogeneous. The diagnosis is often delayed and misdiagnoses can lead to unnecessary treatments. MYH9-RD should be considered in any patient with glomerular involvement associated with a low or slightly decreased platelet count and/or hearing loss and liver dysfunction.

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Alport syndrome (AS) is a hereditary nephropathy characterized by glomerular basement membrane lesions. AS shows a relatively rare entity with autosomal dominant gene mutation (accounts for less than 5% of AS cases) and is widely believed to be a consequence of heterozygous variants in the COL4A3 and COL4A4 genes. Until now, there have been no reports of homozygous variants in genes in AS patients, and it is scarce to detect both homozygous and heterozygous variants in a single AS pedigree. We performed genetic analysis by exome sequencing (exome-seq) in a Chinese family with AS and found four individuals harboring the COL4A4 c.4599T > G variant, a novel COL4A4 nonsense mutation that gains stop codon and results in a truncated protein. The proband and her two siblings were determined to be heterozygous, whereas their mother was homozygous. The proband satisfied the criteria for the diagnosis of AS, which included clinical manifestations of microscopic hematuria and proteinuria, and pathological features of the glomerular basement membrane (GBM), including irregular thickening and splitting. However, the other three individuals who were homozygous or heterozygous for the variant exhibited mild clinical features with isolated microscopic hematuria. In summary, we identified a novel pathogenic variant in either the heterozygous or homozygous state of the COL4A4 gene in a Chinese family with AS. Our results also suggest that the severity of clinical manifestations may not be entirely attributed to by the COL4A4 genetic variant itself in patients.

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End-stage renal disease (ESRD) of undetermined etiology is highly prevalent and constitutes a significant clinical challenge, particularly in the context of kidney transplantation (KT). Despite the identification of numerous rare hereditary nephropathies over the last few decades, patients with undetermined ESRD are not being systematically investigated for rare genetic causes in clinical practice. To address this, we utilized mutation analysis in patients on the kidney transplant waitlist and scrutinized underlying renal diagnoses of 142 patients in a single center KT-waitlist. This cohort was stratified into 85 cases of determined and 57 cases of undetermined ESRD. The latter patients were analyzed by a renal gene panel for mutations in 209 genes associated with ESRD. The most likely genetic diagnoses in 12% of the tested individuals with undetermined ESRD were established. All of these patients showed mutations in genes encoding components of the glomerular filtration barrier. Taken together, hereditary nephropathies, including autosomal dominant polycystic kidney disease, were identified in 35 of the 142 patients of the waitlist cohort. By significantly increasing the proportion of hereditary diagnoses from 29 to 35 patients, the rate of undetermined ESRD significantly decreased from 57 to 51 patients. This study demonstrates the beneficial use of genetic diagnostics in significantly unraveling undetermined ESRD cases prior to KT. Thus, in the absence of renal histology or the presence of unspecific histological conditions, such as hypertensive nephrosclerosis, focal segmental glomerulosclerosis or thrombotic microangiopathy, genetic analysis may provide a robust and specific renal diagnosis and allow for optimizing pre- and post-KT management.

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Objective Alport syndrome was an inherited kidney disease caused by the mutation of COL4A3,COL4A4, or COL4A5. Whole-exome sequencing was used to detect the mutations on these genes for the molecular diagnosis of Alport syndrome. Methods A 6-year-old girl found accidentally with microscopic hematuria at the age of 4. The clinical data and blood sample of the family including proband, parents, brothers, and sisters were collected. Whole exome sequencing was conducted using their genomic DNAs. Results A novel heterozygous frameshift mutation c.1826delC (p.Pro609Glnfs*44) was found in the exon 25 of the COL4A4(NM_000092) in the proband, the father, and the sister, showing an autosomal dominant inheritance pattern of Alport syndrome. This mutation of COL4A4 was confirmed by mutation analysis, and the mutation of c.1826delC was verified by Sanger sequencing. No mutations on COL4A3 and COL4A5 were detected in this family. And the mother and brother are normal wide-type. Conclusions This novel mutation is a valuable addition to the current genetic profile of Alport syndrome, and provide us a better understanding of the disease. Whole-exome sequencing is a power tool to identify the novel mutations of inherited disease and contribute to the molecular diagnosis of disease.

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Objective@#Alport syndrome was an inherited kidney disease caused by the mutation of COL4A3, COL4A4, or COL4A5. Whole-exome sequencing was used to detect the mutations on these genes for the molecular diagnosis of Alport syndrome.@*Methods@#A 6-year-old girl found accidentally with microscopic hematuria at the age of 4. The clinical data and blood sample of the family including proband, parents, brothers, and sisters were collected. Whole exome sequencing was conducted using their genomic DNAs.@*Results@#A novel heterozygous frameshift mutation c.1826delC (p.Pro609Glnfs*44) was found in the exon 25 of the COL4A4 (NM_000092) in the proband, the father, and the sister, showing an autosomal dominant inheritance pattern of Alport syndrome. This mutation of COL4A4 was confirmed by mutation analysis, and the mutation of c.1826delC was verified by Sanger sequencing. No mutations on COL4A3 and COL4A5 were detected in this family. And the mother and brother are normal wide-type.@*Conclusions@#This novel mutation is a valuable addition to the current genetic profile of Alport syndrome, and provide us a better understanding of the disease. Whole-exome sequencing is a power tool to identify the novel mutations of inherited disease and contribute to the molecular diagnosis of disease.

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This is a report of an infant born near term with neonatal stroke and haematuria. Changes were noted on foetal magnetic resonance images, and these persisted postnatally. A routine renal ultrasound scan during follow-up detected haematuria with no associated proteinuria. A likely pathogenic genetic mutation was identified. This case highlights a relatively newly discovered cause for hereditary nephropathy affecting the basement membrane, initially affecting the glomerular but later the renal tubular basement membranes. The renal phenotype, pathogenic genotype and pathological findings on renal biopsy are discussed.

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BACKGROUND: This is a report of an infant born near term with neonatal stroke and haematuria. The renal phenotype, pathogenic genotype and pathological findings on renal biopsy are discussed. CASE-DIAGNOSIS: Prenatal magnetic resonance imaging revealed anomalies which persisted postnatally. Haematuria was detected during follow-up. The posttnatal renal ultrasound scan was normal, and there was no associated proteinuria. A likely pathogenic genetic mutation was detected. CONCLUSIONS: This case highlights a relatively newly discovered cause of hereditary nephropathy in which the basement membrane is affected, with initial effects on the glomerular membranes and subsequent effects on the renal tubular basement membranes.

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BACKGROUND: Symmetric dimethylarginine (SDMA) is a small molecule formed by methylation of arginine, and released into blood during protein degradation. SDMA is primarily eliminated by renal excretion and is a promising endogenous marker of glomerular filtration rate (GFR). OBJECTIVES: To validate an assay for SDMA measurement, determine stability of SDMA in blood, and compare SDMA with serum creatinine concentration (sCr) and GFR for early detection of decreasing kidney function in dogs with chronic kidney disease (CKD). ANIMALS: Eight male dogs affected with X-linked hereditary nephropathy and 4 unaffected male littermates. METHODS: Prospective study validating SDMA measurement using liquid chromatography-mass spectrometry, assessing stability of SDMA in serum and plasma, and serially determining sCr, SDMA, and GFR (using iohexol clearance) in dogs during progression from preclinical disease to end-stage renal failure. Correlations were determined using linear regression. Timepoints at which sCr, SDMA, and GFR identified decreased renal function were compared using defined cutoffs, trending in an individual dog, and comparison with unaffected littermates. RESULTS: Symmetric dimethylarginine was highly stable in serum and plasma, and the assay demonstrated excellent analytical performance. In unaffected dogs, SDMA remained unchanged whereas in affected dogs, SDMA increased during disease progression, correlating strongly with an increase in sCr (r = 0.95) and decrease in GFR (r = -0.95). Although trending improved sCr's sensitivity, SDMA identified, on average, <20% decrease in GFR, which was earlier than sCr using any comparison method. CONCLUSIONS AND CLINICAL IMPORTANCE: Symmetric dimethylarginine is useful for both early identification and monitoring of decreased renal function in dogs with CKD.

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