Long-term auditory monitoring in children with Alport syndrome based on different degrees of renal injury / 临床耳鼻咽喉头颈外科杂志

Objective:To investigate long-term auditory changes and characteristics of Alport syndrome（AS） patients with different degrees of renal injury. Methods:Retrospectively analyzing clinical data of patients diagnosed AS from January 2007 to September 2022, including renal pathology, genetic detection and hearing examination. A long-term follow-up focusing on hearing and renal function was conducted. Results:This study included 70 AS patients, of which 33（25 males, 8 females, aged 3.4-27.8 years） were followed up, resulting in a loss rate of 52.9%.The follow-up period ranged from 1.1to 15.8 years, with 16 patients followed-up for over 10 years. During the follow-up, 10 patients presenting with hearing abnormalities at the time of diagnosis of AS had progressive hearing loss, and 3 patients with new hearing abnormalities were followed up, which appeared at 5-6 years of disease course. All of which were sensorineural deafness. While only 3 patients with hearing abnormalities among 13 patients received hearing aid intervention. Of these patients,7 developed end-stage renal disease（ESRD）, predominantly males （6/7）. The rate of long-term hearing loss was significantly different between ESRD group and non-ESRD group（P=0.013）. There was no correlation between the progression of renal disease and long-term hearing level（P>0.05）. kidney biopsies from 28 patients revealed varying degrees of podocyte lesion and uneven thickness of basement membrane. The severity of podocyte lesion was correlated with the rate of long-term hearing loss（P=0.048）, and there was no correlation with the severity of hearing loss（P>0.05）. Among 11 cases, theCOL4A5mutationwas most common （8 out of 11）, but there was no significant correlation between the mutation type and hearing phenotype（P>0.05）. Conclusion:AS patients exhibit progressive hearing loss with significant heterogeneity over the long-term.. THearing loss is more likely to occur 5-6 years into the disease course. Hearing abnormalities are closely related to renal disease status, kidney tissue pathology, and gene mutations, emphasizing the need for vigilant long-term hearing follow-up and early intervention.

An unusual coalition of medullary nephrocalcinosis with a novel genotypic variant of Alport syndrome type-1

Alport’s syndrome is a type of inherited disorder of the basement membrane characterized by a spectrum of phenotypes ranging from progressive renal injury to varied extrarenal manifestations comprising auditory and ocular abnormalities. Here in, we present a 3-year-old child born out of nonconsanguineous marriage who presented with fever, intermittent microscopic haematuria, and recurrent gross haematuria, proteinuria with normal auditory brainstem response and ocular slit lamp examination findings. Renal biopsy yielded normal light microscopy and immunofluorescence study whereas minimal changes in the glomerular basement membrane (GBM) collagen were detected on electron microscopy, suggesting possibilities of Alport’s syndrome. Ultrasonographic renal imaging yielded the presence of bilateral medullary nephrocalcinosis. Angiotensin converting enzyme inhibitors along with angiotensin receptor blockers were used to curb the disease progression. A final clinical exome sequencing corroborated the phenotype with a diagnosis of Alport’s syndrome type-1 linked to a novel pathogenic variant c.1892dup (p.Gly632ArgfsTer2) showing hemizygous single base pair insertion/duplication in COL4A5 gene. To the best of our knowledge, this unusual association of Alport’s syndrome with medullary nephrocalcinosis has not been reported worldwide in any previous medical literature making this report a primi one.

COL4A5 genotypes and clinical characteristics of children with Alport syndrome / 中国当代儿科杂志

OBJECTIVES@#To investigate the genotypes of the pathogenic gene COL4A5 and the characteristics of clinical phenotypes in children with Alport syndrome (AS).@*METHODS@#A retrospective analysis was performed for the genetic testing results and clinical data of 19 AS children with COL4A5 gene mutations.@*RESULTS@#Among the 19 children with AS caused by COL4A5 gene mutations, 1 (5%) carried a new mutation of the COL4A5 gene, i.e., c.3372A>G(p.P1124=) and presented with AS coexisting with IgA vasculitis nephritis; 3 children (16%) had large fragment deletion of the COL4A5 gene, among whom 2 children (case 7 had a new mutation site of loss51-53) had gross hematuria and albuminuria at the onset, and 1 child (case 13 had a new mutation site of loss3-53) only had microscopic hematuria, while the other 15 children (79%) had common clinical phenotypes of AS, among whom 7 carried new mutations of the COL4A5 gene. Among all 19 children, 3 children (16%) who carried COL4A5 gene mutations also had COL4A4 gene mutations, and 1 child (5%) had COL4A3 gene mutations. Among these children with double gene mutations, 2 had gross hematuria and proteinuria at the onset.@*CONCLUSIONS@#This study expands the genotype and phenotype spectrums of the pathogenic gene COL4A5 for AS. Children with large fragment deletion of the COL4A5 gene or double gene mutations of COL4A5 with COL4A3 or COL4A4 tend to have more serious clinical manifestations.

Clinical analysis of 32 cases of Alport syndrome with predominant COL4A5 gene mutation / 实用医学杂志

Objective To analyze the clinical phenotypes and mutation types of children with X-linked Alport syndrome(XLAS)with mutations in COL4A5 gene,and to explore the relationship between children with XLAS and nephrotic syndrome nephritic type.Methods Thirty-two children with COL4A5 gene mutations detected by second-generation sequencing and finally diagnosed with Alport syndrome at Guangzhou Red Cross Hospital affiliated with Jinan University and the First People's Hospital of Guangzhou between April 2016 and April 2023 were included,and their clinicopathological features and gene mutation characteristics were retrospectively analyzed.Results The mean age of onset of disease in children with XLAS was(3.68±2.07)years old,the mean age at diagnosis(6.56±2.95)years old,12 cases(37.5%)started with isolated hematuria,8 cases(25%)started with hematuria and proteinuria,12 cases(37.5%)started with nephrotic syndrome nephritic phenotype,and the positive family history of the children was found in 11 cases(34.4%),ocular lesions were found in 3 cases(9.37%),ear lesions in 6 cases(18.75%),and 7 cases(21.87%)were found to have developed chronic kidney disease(CKD)in the later follow-up.21 children underwent renal tissue puncture biopsy,and electron microscopy showed thinning of the basement membrane(diffuse or segmental)in 13 cases(61.9%),and uneven thickness of the basement membrane in 8 cases(38.09%);light microscopy showed thinning of the basement membrane in 13 cases(61.9%);light microscopy showed thinning of the basement membrane in 8 cases(38.09%);and light microscopy showed thinning of the basement membrane in 3 cases(11.5%).(38.09%);light microscopy:focal segmental glomerulosclerosis(FSGS)in 2 cases(9.52%),mesangial proliferative glomerulonephritis(Ms PGN)in 11 cases(52.38%),and minimal change disease(MCD)in 8 cases(38.09%).The type of mutation was categorized as missense mutation in 12 cases(37.5%),shear site mutation in 9 cases(28.12%),nonsense mutation in 6 cases(18.75%),deletion mutation in 3 cases(9.37%),and code shift mutation in 2 cases(6.25%).Genetic mutations were present in 22 cases(68.75%);spontaneous mutations were present in 10 cases(27.02%).Conclusions Children with XLAS have atypical clinical manifestations and pathologic features in the early stage of the disease,and the progress is slow,and some of them are easy to be misdiagnosed as nephrotic syndrome nephritis type in the early stage,so it is important to improve the genetic test for this disease as early as possible,and to make reason-able drug choices to predict the prognosis scientifically.

Research progress on pathogenesis and new therapies of Alport syndrome / 中华肾脏病杂志

Alport syndrome (AS), also known as "eye-ear-kidney syndrome or hereditary nephritis", is a common hereditary disorder. AS is caused by pathogenic mutations of type Ⅳ collagen genes ( COL4α3, COL4α4 and COL4α5), leading to defects in the basement membrane of glomeruli, cochlea, and ocular lens. Patients present with hematuria, proteinuria, and progressive renal failure. With the redefinition of AS and the clinical application of high-throughput sequencing technology, the prevalence of AS may be much higher than the previously recognized. The specific pathogenic mechanism of AS is unknown. Recent studies have showed that type Ⅳ collagen gene mutation may lead to kidney injury by causing abnormal basement membrane components, lipid deposition, energy metabolism disorders, endoplasmic reticulum stress, inflammation and fibrosis. Renin-angiotensin system inhibitor is the main therapy of AS, but the effect is not satisfactory. The new therapeutic strategies mainly include inhibition of abnormal collagen signal transduction, reduction of endoplasmic reticulum stress in podocytes, regulation of energy metabolism, antioxidant stress, anti-inflammation and fibrosis, gene and stem cell therapy. The paper reviewed the research progress on pathogenesis and new therapies of AS.

Deciphering the pathogenicity of COL4A4 heterozygous splicing mutations and the genotype-phenotype correlation in autosomal dominant Alport syndrome / 中华肾脏病杂志

Objective:Through the investigation of the pathogenicity of COL4A4 heterozygous splicing mutations and the genotype-phenotype correlation in autosomal dominant Alport syndrome (ADAS), to better understand the impact of COL4A4 heterozygous splicing mutations on ADAS. Methods:The study was a case series analysis. Patients from 5 ADAS families with COL4A4 heterozygous splicing mutations detected by whole exome sequencing were recruited by three hospitals. In vivo transcriptional analysis and/or in vitro minigene splicing assay were conducted to determine the splicing patterns and assess the pathogenicity of COL4A4 heterozygous splicing mutations. Results:In the five ADAS pedigrees carrying COL4A4 heterozygous splicing mutations, four novel ADAS splicing patterns were described. In pedigree 1-4, most patients presented with continuous hematuria or/and microalbuminuria. Otherwise,the proband in pedigree 4 presented with macroalbuminuria and the proband in pedigree 1 had progressed to chronic kidney disease stage 2 at the age of 70 years old. In pedigree 5, all patients developed end-stage renal disease between 28 and 41 years old. c.735+3A>G detected in pedigree 1 and pedigree 2 and c.694-1G>C detected in pedigree 3 both led to exon 12 skipping in COL4A4, resulting in 42 nucleotides in-frame deletion (c.694_735del). c.2056+3A>G detected in pedigree 4 led to COL4A4 exon 26 skipping, which caused in-frame deletion of 69 nucleotides (c.1988_2056del). c.2716+5G>T detected in pedigree 5 led to a 360 nucleotides large in-frame deletion, including 100 bp sequence at the 3'end of exon 29,the whole sequence of exon 30 and 89 bp sequence at the 5'end of exon 31 (c.2446_2805del). Conclusions:Renal prognosis differs significantly for patients with small in-frame deletions versus large in-frame deletion splicing abnormalities. Determination of the pathogenicity and the splicing patterns of COL4A4 heterozygous splicing mutations using in vivo and in vitro transcriptional analysis may provide renal prognostic information.

Advances in the treatment of Alport syndrome / 国际儿科学杂志

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.

Bilateral giant full thickness macular holes: an infrequent manifestation of alport syndrome

Purpose: To report a case of Alport syndrome presenting with bilateral giant full-thickness macular holes, hypertensive chorioretinopathy, and exudative retinal detachment. Case Report: A 20 year-old man, a known case of Alport syndrome on hemodialysis, was referred to our clinic with bilateral vision loss initiated about 10 years prior to presentation, which exacerbated in the month prior to our visit. Bilateral large full-thickness macular holes, hypertensive chorioretinopathy, and exudative retinal detachment were detected in fundus examination. The patient had previous genetic counseling confirming the diagnosis of Alport syndrome. During follow-up, macular holes were covered with a thick epiretinal membrane and visual acuity decreased progressively in two weeks. Pars plana vitrectomy was performed in the right eye. Two weeks following surgery, the macular hole was closed and visual acuity improved significantly. Conclusion: Bilateral giant full-thickness macular holes are uncommon presentations of Alport syndrome. The retinal findings may be caused by an inefficient type IV collagen presenting in the Bruch's membrane and in the internal limiting membrane. Pars plana vitrectomy can be considered to repair macular holes in these patients.

Fenotipos inesperados en el síndrome de Alport: la necesidad del estudio genético / Unexpected phenotypes in Alport syndrome: the need for genetic testing

El diagnóstico del síndrome de Alport supone un reto en la edadpediátrica, debido a la ausencia de fenotipos clínicos esperados de la enfermedad, su clásica caracterización de entidad rara y la práctica muy restringida de biopsias renales con análisis rutinario de la muestra por microscopía electrónica durante la infancia. Se presentan las características clínicas y genéticas de 6 pacientes pediátricos (4 mujeres) diagnosticados de síndromede Alport en dos centros hospitalarios entre 2018 y 2021. Todos los pacientes presentaron un debut clínico claramente diferente y ninguno presentó complicaciones auditivas nioftalmológicas. La mitad carecía de antecedentes familiares de enfermedad renal crónica. Ninguna biopsia renal realizada confirmó el diagnóstico. Todos los pacientes fueron confirmadosgenéticamente y fueron el caso índice del estudio familiar. Esta serie ilustra la presencia de fenotipos clínicos inesperados en el síndrome de Alport y refleja la necesidad de incorporar el estudio genético para su diagnóstico.

The diagnosis of Alport syndrome is a challenge in the pediatric age, due to the absence of expected clinical phenotypes of the disease, its classic characterization of a rare disease and the very restricted practice of renal biopsies with routine analysis of the sample by electron microscopy during infancy. The clinical and genetic characteristics of 6 pediatric patients (4 women) diagnosed with Alport syndrome in two hospital centers between 2018 and 2021 are reported. All patients presented a clearly different clinical debut and none presented auditory or ophthalmological complications. Half had no family history of chronic kidney disease. No kidney biopsy performed confirmed the diagnosis. All patients were genetically confirmed and were the index case in the family study. This series illustrates the presence of unexpected clinical phenotypes in Alport syndrome and reflects the need for the incorporation of the genetic study for its diagnosis.

Whole-Exome Sequencing (WES) results of 50 patients with chronic kidney diseases: a perspective of Alport syndrome

SUMMARY OBJECTIVE: Chronic kidney disease (CKD) remains one of the major common health problems, and the number of people affected by the disease is progressively increasing in Turkey and worldwide. This study aimed to investigate molecular defects in Alport syndrome (AS) and other genes in patients with clinically suspected CKD using whole-exome sequencing (WES). METHODS: Patients with clinical suspicion of CKD were included in the study. Molecular genetic analyses were performed on genomic DNA by using WES. RESULTS: A total of 15 with 5 different pathogenic or likely pathogenic variants were identified in CKD patients, with a diagnostic rate of 30%. Eight variants of uncertain significance were also detected. In this study, 10 variants were described for the first time. As a result, we detected variants associated with CKD in our study population and found AS as the most common CKD after other related kidney diseases. CONCLUSIONS: Our results suggest that in heterogeneous diseases such as CKD, WES analysis enables accurate identification of underlying molecular defects promptly. Although CKD accounts for 10-14% of all renal dysfunction, molecular genetic diagnosis is necessary for optimal long-term treatment, prognosis, and effective genetic counseling.

Síndrome de Alport: Rol de la semiología y la genética

El síndrome de Alport es una enfermedad renal progresiva por alteración de la membrana basal glomerular secundaria a mutación en los genes COL4A4, COL4A5 y COL4A6 del colágeno tipo IV, con 3 patrones hereditarios: ligado al cromosoma X, autosómico dominante y autosómico recesivo. No existe tratamiento específico para el síndrome de Alport, el objetivo del tratamiento es evitar la progresión rápida a enfermedad renal crónica y mejorar la calidad de vida del paciente. Se reporta el caso de una femenina de 5 años que acudió al cuarto de urgencias con historia de dolor abdominal y edema en miembros inferiores con hematuria microscópica, resto de exámenes de laboratorio y gabinete con hallazgos sugestivos de apendicitis aguda. Se realizó diagnóstico de apendicitis aguda y síndrome nefrítico, sin embargo, debido a la persistencia de hematuria con proteinuria e historia familiar de hematuria, se sospecha de síndrome de Alport.  Inició tratamiento con inhibidores de la enzima convertidora de angiotensina y se realizó biopsia renal reportada sin alteraciones a la microscopía de luz sin reporte de microscopía electrónica. Cursó con proteinuria en rango nefrótico, inicia tratamiento con corticoides e inhibidores de calcineurina sin respuesta. Se obtiene reporte de panel genético confirmatorio de Alport y se suspende inmunosupresión. (provisto por Infomedic International)

Alport syndrome is a progressive kidney disease, due to alterations of the glomerular basement membrane secondary to mutations in the COL4A4, COL4A5 and COL 4A6 genes of type IV collagen with three hereditary patterns: X-linked, autosomal dominant and autosomal recessive. There is no specific treatment for Alport Syndrome. The main goal of the therapeutic options is to prevent rapid progression to chronic kidney disease and improve the patient's quality of life. The report of a 5-year-old female, who attended the emergency room with abdominal pain, edema in the lower limbs and microscopic hematuria, the rest of the laboratory and clinical studies with findings suggestive of acute appendicitis. A diagnosis of acute appendicitis and nephritic syndrome was made, however, due to the persistence of hematuria and family history, Alport syndrome was suspected. Treatment with angiotensin-converting enzyme inhibitors was started and renal biopsy was performed, reported minimal change and without electron microscopy report. The patient quickly progressed to nephrotic range proteinuria and started corticosteroids and calcineurin inhibitors without response.  A confirmatory genetic panel was performed, Alport syndrome was diagnosed, and immunosuppression was suspended. (provided by Infomedic International)

Glomerulonefritis C3 en un paciente con síndrome de Alport: un caso raro

El síndrome de Alport es una entidad hereditaria que se produce principalmente por una mutación en los genes que codifican el colágeno tipo IV. Por otro lado, la glomerulonefritis C3 es una entidad rara que presenta un patrón de glomerulonefritis membranoproliferativa y su etiología se basa en un control anormal de la activación de la vía alternativa del complemento. A continuación se describe un caso de un paciente, de sexo masculino, que cursa con un síndrome nefrótico corticorresistente en el que se documenta un patrón de glomerulonefritis membranoproliferativa en la biopsia renal con depósitos de C3 en la inmunofluorescencia, asociada a una deleción heterocigota en el gen CFHR1 en el estudio genético de las proteínas reguladoras del complemento. Además, en el panel genético realizado por corticorresistencia se encuentra una variante COL4A5 asociada al síndrome de Alport ligado al X. Estas entidades pueden presentarse con un curso clínico diverso, pero al estar asociadas pueden acelerar la progresión a enfermedad renal crónica, por lo que se hace necesario hacer un seguimiento clínico más estricto.

Alport Syndrome is a hereditary entity that occurs mainly due to a mutation in the genes that encode type IV collagen. C3 glomerulonephritis is a rare entity with a pattern of membranoproliferative glomerulonephritis and its etiology is based on abnormal control of the activation of the alternative complement pathway. We describe a case of a male patient who presents with a corticosteroid nephrotic syndrome in which a pattern of membranoproliferative glomerulonephritis is documented in the renal biopsy with C3 deposits in the immunofluorescence, associated with a heterozygous deletion in the gene CFHR1 in the genetic study of complement regulatory proteins. Furthermore, a variant COL4A5 associated with X-linked Alport syndrome is found in the genetic panel for corticosteroid resistance. These entities can present with a diverse clinical course, but when associated they can accelerate progression to chronic kidney disease, which is why makes it necessary to do a more strict clinical follow-up.

Thin basement membrane nephropathy combined with juvenile idiopathic arthritis caused by the COL4A4 gene mutation: a case report / 中华实用儿科临床杂志

To analyze a case of thin basement membrane nephropathy combined with juvenile idiopathic arthritis diagnosed in November 2017 in Children′s Hospital of Chongqing Medical University.A male patient with 7 years and 11 months old presented with swelling of bilateral interphalangeal joints and abnormal gait was diagnosed as juve-nile idiopathic arthritis.Urine examination revealed microscopic hematuria.Long-term follow-up after discharge showed recurrent joint symptoms and persistent microscopic hematuria.In February 2019, genetic testing showed the COL4A4 gene mutation (c.3479G>A p. G1160E). Through literature review, a case of rheumatoid arthritis complica-ted with Alport syndrome caused by the COL4A5 gene mutation c. 1351T>C (p.Cys451Arg) was previously reported.Both of 2 patients were diagnosed as collagen type Ⅳ-related renal diseases complicated with arthritis, and multiple joints involvement and renal involvement were detected.Excluding the influence of accidental factors and drugs, arthritis and some kidney diseases may have a co-pathogenesis under genetic background.The specific mechanism needs further exploration.This case report provided novel direction for the diagnosis and treatment of relevant diseases.

Genotype and phenotype analysis of children with autosomal dominant inheritance Alport syndrome / 中华实用儿科临床杂志

Objective:To analyze the clinicopathological and gene mutation characteristics of children with autosomal dominant inheritance Alport syndrome (ADAS), and to improve the understanding of ADAS.Methods:Ten children with ADAS diagnosed in the Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology from September 2016 to February 2020 were enrolled.The clinicopathological and gene mutation features were retrospectively analyzed, and the patients were followed up.Results:(1) The median age at diagnosis was 5.7 (2.4, 9.8) years.Of 10 children, 6 cases (60.0%) showed a family history of renal failure, 4 cases (40.0%) presented with hematuria and proteinuria at diagnosis, and 2 cases (20.0%) suffered a high-frequency hearing loss.Renal biopsy showed extensive splitting and lamellation of the glomerular basement membrane (GBM) dense layer in 4 cases (40.0%), and segmental splitting and lamellation in 6 cases (60.0%). (2)Among 10 children, 4 cases (40.0%) were heterozygous mutations of COL4A3 gene, including 2 point mutations of glycine, and 2 splicing mutations.The other 6 cases (60.0%) were heterozygous mutations of COL4A4 gene, including collagen glycine point mutations in 4 cases, nonsense mutation in 1 case and large deletion in 1 case.Six mutations were new and never reported before. Conclusions:The early clinical presentations of children with ADAS are often atypical and extrarenal manifestations are less common.The GBM dense layer is mainly featured by segmental splitting and lamellation.Glycine point mutations account for the majority of the gene mutations.

Clinical, Pathological and Genetic Analysis of Alport Syndrome in Children / 罕见病研究

  Objective  To explore the phenotype-genotype correlation of Alport syndrome in children.  Methods  Retrospectively analyze the clinical and pathological features of 55 patients with Alport syndrome with COL4A mutations detected by second-generation sequencing, who were treated at Beijing Children's Hospital from January 2016 to December 2020.  Results  A total of 55 children with Alport syndrome were included. All cases had hematuria, including 31 cases (56.4%) with gross hematuria and 24 cases (43.6%) with microscopic hematuria. A total of 39 (70.9%) patients also had proteinuria. Extrarenal manifestations were pres- ent in 12 patients (21.8%). 36(65.4%) patients had a family history of Alport syndrome. 32 patients underwent pathological examination and 23 of them had the specific pathological changes of Alport syndrome. In 55 cases, 36 (65.4%) were diagnosed as X-linked Alport syndrome, 5(9.1%) were diagnosed as autosomal recessive Alport syndrome, 10(18.2%) were diagnosed as autosomal dominate Alport syndrome, and 4(7.3%) were diagnosed as digenic Alport syndrome. Missense mutations in COL4A genes accounted for 62.5%, 67.5% of missense mutations resulted in glycine substitution. There were statistical significances in proteinuria degree and hearing loss between male and female patients with XLAS (P < 0.05) as well as statistical significance in the degree of proteinuria between autosomal recessive Alport syndrome and autosomal dominate Alport syndrome (P=0.044), and there was critical statistical significance in the age of onset. There was statistical significance in hearing loss between children with renal impairment and children with normal renal function (P=0.001).  Conclusions  Most of the pathogenic variants in COL4A genes that cause Alport syndrome result in glycine substitutions. The degree of proteinuria and hearing loss of males with XLAS were greater than those of females. The degree of proteinuria in autosomal recessive Alport syndrome was greater than that of children with autosomal dominate Alport syndrome, and the age of onset was earlier than that of autosomal dominate Alport syndrome. Renal manifestation was more severe in children with hearing loss. The early clinical manifestations of Alport syndrome are diverse and pathological manifestations may be atypical. The application of next-generation sequencing can reduce misdiagnosises of Alport syndrome.

Clinical characteristics and gene analysis of a family with autosomal dominant Alport syndrome with the onset of nephrotic syndrome / 中华实用儿科临床杂志

The clinical characteristics, mutation analysis results, and family tree of a patient with autosomal dominant Alport syndrome (ADAS), who had nephrotic syndrome as the first manifestation were examined.The proband was a 11-month-old girl who presented with nephrotic syndromes and gross hematuria.During the treatment course, the patient had steroid resistance and a poor response to Cyclosporine and Cyclophosphamide pulse therapy.Renal biopsy was performed 2 years after disease onset.Under the light microscopy, glomerular segmental mesangio-proliferative lesions were observed.The staining of type Ⅳ collagen showed the loss of the α3 chain in the glomerular basement membrane (GBM) and tubular basement membrane, and α5 chain loss in GBM.Electron microscopy showed uneven thickness of GBM, with obviously delaminated and tearing dense basement membrane (BM) layer, showing a typical lace-like change.The segmental BM was loosened and widened.Her father did not develop microscopic hematuria until 10 years later, while her grandmother had asymptomatic hematuria and proteinuria when the proband was diagnosed.A new mutation in the COL4A4 gene was found in the proband, namely c. 1715delG (p.G572Vfs * 81). Her father and grandmother carried the same mutation, but her mother and sister did not have.The clinical manifestation of ADAS is clinically heterogeneous and its incidence may be higher than what we have expected.

Analysis and literature review of COL4A5 mutation mosaicism in male patients with X-linked Alport syndrome / 中华肾脏病杂志

Objective:To report four male COL4A5 mutation mosaicism patients with X-linked Alport syndrome, and to provide evidence for diagnosis, genetic counseling, and reproduction in the respective families and improve our knowledge of mosaicism in Alport syndrome. Methods:Suspected male mosaic patients for COL4A5 who met the following criteria: clinical diagnosis of Alport syndrome, harbored COL4A5 mutations detected using next generation sequencing or Sanger sequencing, heterozygosity for the mutant and normal COL4A5 alleles in the DNA demonstrated by Sanger sequencing, registered in the on-line registry of hereditary kidney diseases, and admitted to Peking University First Hospital during the period of April 2018 to April 2019 were enrolled. Clinical data and karyotypes were retrospectively analyzed. Genetic DNA isolated from multiple tissues was analyzed for COL4A5 gene mutations by using PCR and Sanger sequencing. Related literatures published in PubMed, CNKI and Wanfang databases were reviewed. Results:Four COL4A5 somatic and germline mosaic male patients with Alport syndrome were included in the study. Patient 1 was characterized by hematuria and proteinuria. His karyotype of peripheral blood was normal. COL4A5 c.3455-1G>A mosaicism was detected in multiple tissues (peripheral blood, saliva and urine). Patient 2 presented with hematuria and microalbuminuria. His karyotype of peripheral blood was normal. COL4A5 c.4994+1G>A mosaicism was detected in multiple tissues (peripheral blood, saliva and skin fibroblasts). Patients 3 showed hematuria without proteinuria. COL4A5 c.3535G>A mosaicism was found in genomic DNA of peripheral blood and hair. Laboratory and physical examinations of patient 4 showed hematuria and normal renal function, without proteinuria, megasoma or small testes. COL4A5 c.3106G>A mosaicism was detected in genomic DNA of skin fibroblasts. Although without karyotype analysis due to unavailable specimens, 47,XXY or 46,XY/47,XXY mosaicism was not considered according to the reproductive history and lack of clinical manifestations of megasoma and small testes in patients 3 and 4. Renal disease in 8 published male cases with mosaicism for COL4A5 was affected by mutant allelic fractions and genotype. Conclusions:Compared with hemizygous males with X-linked Alport syndrome, the renal phenotype of mosaic males was milder, and associated with mutant allelic fractions and mutation type.

Pathogenicity evaluation and splicing correction of COL4A5 splice mutation in X-linked Alport syndrome / 中华肾脏病杂志

Objective:To analyze the splicing mutation site of COL4A5 gene in a family with X-linked dominant Alport syndrome and explore the possibility of exon specific U1 small nuclear RNA (snRNA) gene therapy. Methods:The clinical data of the proband and family members of Alport syndrome were collected, and the gene mutations in the whole exon of a series of nephropathy genes in the proband were detected by high-throughput sequencing. The splice site changes and pathogenicity caused by COL4A5 c.546+5G>A mutation were analyzed by online software. Minigene experiment was used to verify and analyze the effect of COL4A5 gene mutation site c.546+5G>A in the proband of Alport syndrome family, and transient transfection and introduction of modified U1 snRNA to correct splicing mutation. Results:The results of gene sequencing showed that there was a hemizygous variation of COL4A5 gene in the proband and his half brother, and the variation site was c.546+5G>A. The results of online software for analyzing the pathogenicity of splice variation showed that the original donor splicing site could not be detected after mutation, suggesting that there was a great possibility of affecting splicing. The abnormal splicing mode of COL4A5 gene with c.546+5G>A mutation—deletion of exon 9 was verified by hybridized small gene detection. The abnormal splicing mutation could be partially corrected by the modified U1 snRNA. The correction ratios of ExSpeU1 (MT), ExSpeU1(E9+1), ExSpeU1(E9+9) and ExSpeU1(E9+11) to exon 9 deletion caused by c.546+5G>A were 0, 43.81%, 52.09% and 48.12%, respectively. Conclusions:The pathogenicity of the new splicing mutation of COL4A5 is verified, and the modified U1 snRNA can partially correct the abnormal splicing.

Una nueva variante del gen COL4A4 (c.1856G> A). De un caso de glomeruloesclerosis focal y segmentaria a una familia con síndrome de Alport / A novel COL4A4 gene variant (c.1856G>A): from a focal segmental glomerulosclerosis case to a family with Alport syndrome

El síndrome de Alport (SA), también conocido como nefritis hereditaria, es una forma progresiva hereditaria de enfermedad glomerular que a menudo se asocia con pérdida auditiva neurosensorial y anomalías oculares. Es causada por mutaciones en los genes que codifican varios miembros de las proteínas de colágeno del tipo IV, que se hallan en las membranas basales principalmente. Los análisis genéticos de las familias afectadas han identificado cuatro modos diferentes de transmisión en pacientes con síndrome de Alport. La forma del síndrome ligada al X surge a partir de mutaciones de COL4A5 y COL4A6 en el cromosoma X, mientras que las formas autosómicas resutan de defectos genéticos tanto en el gen COL4A3 como en el COL4A4, en el cromosoma 2q35-37. Las formas digénicas incluyen pacientes con mutaciones coexistentes en COL4A3, COL4A4 y COL4A5. El resultado clínico a largo plazo en pacientes con SA con mutaciones heterocigotas de COL4A3/A4es generalmente impredecible. La glomeruloesclerosis focal y segmentaria suele desarrollarse en el SA clásico en etapas posteriores y se presenta predominantemente con proteinuria asociada con hematuria. En el caso índice presentado en este informe, a un hombre de 26 años se le realizó una biopsia de riñón debido a una proteinuria nefrótica y una hematuria microscópica acompañada de una función renal alterada. Se le diagnosticó glomeruloesclerosis focal y segmentaria. Debido a que tenía una pérdida auditiva progresiva desde el inicio del estudio, se le realizó un estudio genético de mutaciones en los genes COL4A3 y COL4A4. Se detectó una nueva mutación en el gen COL4A4 (c.1804-7T> C).Debido a que sus padres tenían un matrimonio consanguíneo, el resto de la familia fue sometida a estudio para la misma variante. Sus padres y su hermana fueron heterocigotos y homocigota para la misma variante, respectivamente. En este estudio, se demostró la existencia de una familia con síndrome de Alport con una nueva mutación en el gen COL4A4 (c.1856G> A) que, según sabemos, es el primer caso reportado.

Alport syndrome, also known as hereditary nephritis, is an inherited progressive form of glomerular disease that is often associated with sensorineural hearing loss and ocular abnormalities. It is caused by mutations in genes encoding several members of type IV colagen proteins primarily found in basement membranes. Genetic analyses of affected families have identified four different modes of transmission in patients with Alport syndrome. X-linked form of the syndrome arises from mutations of COL4A5 and COL4A6 on chromosome X, whereas autosomal forms result from genetic defects in either the COL4A3 or COL4A4 genes at chromosome 2q35-37. Digenic forms include patients with coexisting mutations in COL4A3, COL4A4, and COL4A5. The long-term clinical outcome in AS patients with heterozygous COL4A3/A4 mutations is generally unpredictable. Focal segmental glomerulosclerosis usually develops in classical AS at later stages and presents predominantly with proteinuria associated with hematuria. The index case presented in this report, a 26-year-old man, had kidney biopsy because of nephrotic proteinuria and microscopic hematuria accompanied by impaired renal function. He diagnosed focal segmental glomerulosclerosis. As he had progressive hearing loss since chidhood we conducted a genetic study for mutations in COL4A3 and COL4A4 genes. A novel mutation in COL4A4 gene (c.1804-7T>C) was detected. As his parents had consanguineous marriage we investigated the rest of the family for the same variant. His parents, and his sister were found to be heterozygote, and homozygote for the same variant, respectively. In this report we demonstrated an Alport syndrome family with a novel mutation in COL4A4 gene (c.1856G>A) that has been first reported to our best knowledge.