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.

Long-term Prognosis of thin Glomerular Basement Membrane Nephropathy in Children: A Retrospective Single Center Study

PURPOSE: Thin glomerular basement membrane nephropathy (TBMN) is, along with the IgA nephropathy, the most common cause of asymptomatic hematuria in Korean children. TBMN is usually a benign renal disease not requiring treatment and is associated with a good prognosis, but some cases hematuria is indicative of a state of progressive renal insufficiency. We aimed to retrospectively evaluate clinical manifestations and renal prognosis of patients with TBMN. METHODS: Among the 428 renal biopsies performed on children at Yeungnam University Hospital between January 2000 and February 2017, 167 patients were diagnosed as having TBMN. We retrospectively investigated 167 pediatric patients and identified 59 children with follow-up duration >3 years. RESULTS: Among 59 patients, there were 33 boys and 26 girls. Mean age of onset of hematuria was 7.18±2.64 years, and mean time from onset of disease until a renal biopsy was performed was 2.48±2.10 years. There were no clinical features or laboratory findings among studied children to indicate decreased renal function during follow-up; however, one case progressed to chronic kidney disease (CKD) due to an unknown cause. There were seven patients among these related a positive family history of hematuria or renal insufficiency. CONCLUSION: Although almost all patients had normal renal functions during follow-up, there were one patient who progressed to CKD and seven patients with family history of hematuria or renal insufficiency. Moreover, four among the 428 patients over 17 years underwent repeat renal biopsies, which showed results different from their earlier biopsies.Thus, large-scales studies may be required to determine long-term prognosis of TBMN in children, and further evaluation for Alport syndrome in TBMN cases is essential.

Long-term Prognosis of thin Glomerular Basement Membrane Nephropathy in Children: A Retrospective Single Center Study

PURPOSE: Thin glomerular basement membrane nephropathy (TBMN) is, along with the IgA nephropathy, the most common cause of asymptomatic hematuria in Korean children. TBMN is usually a benign renal disease not requiring treatment and is associated with a good prognosis, but some cases hematuria is indicative of a state of progressive renal insufficiency. We aimed to retrospectively evaluate clinical manifestations and renal prognosis of patients with TBMN. METHODS: Among the 428 renal biopsies performed on children at Yeungnam University Hospital between January 2000 and February 2017, 167 patients were diagnosed as having TBMN. We retrospectively investigated 167 pediatric patients and identified 59 children with follow-up duration >3 years. RESULTS: Among 59 patients, there were 33 boys and 26 girls. Mean age of onset of hematuria was 7.18±2.64 years, and mean time from onset of disease until a renal biopsy was performed was 2.48±2.10 years. There were no clinical features or laboratory findings among studied children to indicate decreased renal function during follow-up; however, one case progressed to chronic kidney disease (CKD) due to an unknown cause. There were seven patients among these related a positive family history of hematuria or renal insufficiency. CONCLUSION: Although almost all patients had normal renal functions during follow-up, there were one patient who progressed to CKD and seven patients with family history of hematuria or renal insufficiency. Moreover, four among the 428 patients over 17 years underwent repeat renal biopsies, which showed results different from their earlier biopsies.Thus, large-scales studies may be required to determine long-term prognosis of TBMN in children, and further evaluation for Alport syndrome in TBMN cases is essential.

Childhood hepatolenticular degeneration combined with thin basement membrane nephropathy: a case report with literature review / 临床儿科杂志

Objective To analyze the diagnostic approach on hepatolenticular degeneration combined with thin basement membrane nephropathy.Methods A girl presented with microscopic hematuria, liver dysfunction and hypocomplementemia was diagnosed with hepatolenticular degeneration combined with thin basement membrane nephropathy, her clinical data were summarized and analyzed retrospectively.Results A ten years old girl presented with microscopic hematuria and liver dysfunction for a year, dysarthria for a month, and combined with hypocomplementemia but without proteinuria. Renal biopsy showed thin basement membrane nephropathy. Ceruloplasmin was 23.10 mg/L and urinary copper concentration was 120μg, respectively, ocular slit lamp examination showed Kayser-Fleischer ring, cranial MRI showed preternatural signal in both basal and putamen nucleus, mutation analysis showed homozygous mutations in ATP7B and heterozygous mutation in COL4A3 gene,respectively.Conclussion Hepatolenticular degeneration should be suspected in those cases with persistence microscopic hematuria, liver dysfunction and hypocomplementemia.

Research progress of benign familial hematuria / 中华实用儿科临床杂志

Benign familial hematuria,also called thin basement membrane nephropathy,is caused by a heterozygous mutation in the COL4A3 or COL4A4 gene.The prognosis of the patients with benign familial hematuria,who present isolated hematuria without associated with proteinuria and normal renal function,is good in childhood.However,the prognosis of part of the patients with benign familial hematuria,who appear proteinuria,hypertension,chronic renal failure and end-stage kidney disease,is poor in adulthood.Therefore,the patients with benign familial hematuria should be carried on the long-term follow-up,and may be reviewed every 1-2 years for hypertension,proteinuria,and renal impairment.Treatment for benign familial hematuria should include an angiotensin converting enzyme inhibitor to delay the onset of renal failure.

Identification of a novel COL4A4 mutation in a family with thin-basement-membrane nephropathy and the pathogenic mechanism / 中华肾脏病杂志

Objective To explore a new pathogenic gene mutationin in COL4A3 and COL4A4 genes of a family with thin-basement-membrane nephropathy (TBMN), and explain its mechanism.Methods Genomic DNA was extracted from blood samples.Mutation screening for all the exons in COL4A3 and COL4A4 of the proband was carried out by direct PCR sequencing.The sequences of the proband were compared with standard sequences in GenBank.After identifying the mutation in COL4A4, screening for the mutation site in 200 healthy controls and the rest of family members were conducted.RNA sequence of the proband was analyzed by reverse transcription PCR and TA cloning.The positive clones were sequenced for RNA screening.Results There was a G to A mutation in the 1459 site of COL4A4 (c.1459+G ＞ A) in the proband, her mother, and the elder sister, whereas the mutation was not found in other family members and healthy people.RNA screening showed that the COL4A4 (c.1459+G ＞ A) mutation was a heterozygous substitution in position + 1 of exon 21, in the splicing region.This mutation leaded to eliminating of exon 21 from the COL4A4 mRNA, causing the exon 21 deletion and frameshift mutation following the exon 20 in its amino acids sequence.Conclusions It is described that COL4A4 (c.1459+G ＞ A) is a new pathogenic mutation in TBMN, which further help understanding the pathogenesis and clinical diagnosis of TBMN.

Clinical and pathological research on 148 cases of glomerular minor lesion / 中华肾脏病杂志

Objective To analyze cases diagnosed with glomerular minor lesion (GML) by light microscopy and immunofluorescence,uncover their final pathology diagnosis by electron microscopy,and thereby clarify the pathological and clinical meaning of GML.Methods One hundred and forty-eight patients receiving renal biopsy between 2003 and 2008 in Peking Union Medical College Hospital,with diagnosis of GML described by light microscopy and immunofluorescence examination were retrospectively studied.All the clinical data and pathological observation were collected and analyzed,including intact results of electron microscopic examination which were considered as golden standards of pathological diagnosis.Results The 148 patients with GML had heterogenous clinical features,with isolated hematuria as the most common presentation.Electron microscopy revealed various pathological presentations:thin basement membrane nephropathy (TBMN,66.2％),mesangial proliferative glomerulonephritis (MsPGN,20.3％),Alport syndrome (2.7％),membranous nephropathy (MN,3.4％),normal tissue (4.7％).Among GML patients with isolated hematuria,TBMN ranked as the most common pathology (76.9％).Conclusions GML is only an equivocal description of pathological manifestation by light microscopy and immunofluorescence examination.And electron microscopy is necessary to obtain accurate pathology diagnosis for patients undergoing renal biopsies.

A female patient of Fabry disease complicated with thin basement membrane nephropathy and investigation of the kindred / 中华肾脏病杂志

Objective To elucidate the features of clinicopathology and mutation in Fabry disease complicated with thin basement membrane nephropathy (TBMN), and to investigate the kindred. Methods Data of clinicopathology and gene mutation of a female patient of Fabry disease complicated with TBMN admitted to the Department of Nephro]ogy in our hospital were analyzed. Members of her kindred were investigated simultaneously. Results Proband was a 41-year-old Chinese woman who presented syndrome of Fabry disease and TBMN including angiokeratomas, chronic pain, tinnitus, vertigo, left ventricular hypertrophy and nephropathy as proteinuria, microscopic hematuria and hypertension. A percutaneous renal biopsy was performed on the proband, which was consistent with FSGS and vaculization of podocytes by light microscopy.Electron microscopy showed concentric lamellated inclusions in some podocytes. Diffuse thinning of glomerular basement membrane (GBM) with a mean thickness of (216±31) nm was found. The diagnosis of TBMN with suspected Fabry disease was identified. Family screening showed that her daughter had microscopic hematuria, tinnitus and neuropathic pain. One of her sisters only had microscopic hematuria. The activity of α-galacsidase A (α-Gal A )enzyme in the proband and her daughter was 33 units and 75 units respectively (the normal range is 100 to 500 units). They all carried the novel GLA mutation 1208 ins 21 bp and COL4A3 SNP c: 3627G＞A(p:M1209I). While her sister who only had microscopic hematuria just carried the variant of COL4A3 gene-c:3627G ＞A (p:M1209I), and had the normal activity of α-Gal A with no mutation of GLA.Conclusion TBMN should be considered in the patients of Fabry disease with the condition of benign familial hematuria.

Identifi cation of novel variants in the COL4A4 gene in Korean patients with thin basement membrane nephropathy.

Background & objectives: The α4 chain of the type 4 collagen family is an important component of the glomerular basement membrane (GBM) in the kidney. It is encoded by the COL4A4 gene, and mutations of this gene are known to be associated with thin basement membrane nephropathy (TBMN). To better understand the contribution of variants in the COL4A4 gene to TBMN, we investigated the sequence of the complete COL4A4 gene in 45 Korean patients with TBMN. Method: Genomic DNA was obtained from the peripheral blood lymphocytes. For the analysis of the COL4A4 gene, all the exons including splicing sites were amplififi ed by PCR and screened by direct sequencing analysis. Results: Eight novel COL4A4 sequence variants were found in these patients. Two of these variants, G199R and G1606E, were possibly pathogenic variants affecting the phenotype. None of these variants were observed in 286 chromosomes from normal Korean control subjects. In addition, 39 polymorphisms including 7 novel SNPs were identifi ed in this study. Interpretation & conclusion: The frequency of COL4A4 mutations in Korean patients with TBMN is low and the other cases may have mutations in other genes like COL4A3. Screening of the COL4A3 gene and fi nding a novel causative gene for TBMN will help clarify the pathogenesis of this disorder and perhaps for distinguishing TBMN from Alport syndrome.

Mutation analysis of COL4A3/COL4A4 genes in a family with thin basement membrane nephropathy and focal segmental glomerulosclerosis / 中华肾脏病杂志

Objective To elucidate whether focal segmental glomerulosclerosis (FSGS) is a secondary development of the COL4-linked thin basement membrane nephropathy (TBMN) or the primary FSGS produces thin glomerular basement membrane (GBM). Methods The family members presented microscopic hematuria,increasing proteinuria with the years and a dual pathological diagnosis of FSGS and TBMN was made in the proband.DNA linkage analysis at locus 2q36-37 that contains the COL4A3/COL4A4 genes was performed with polymorphic micmsateilite markers D2S434,D2S279,D2S1370,D2S256 and D2S427.Haplotypes were constructed at the COL4A3/COL4A4 loci for affected and unaffected family members.All exons of COL4A3 and COL4A4 genes were screened for mutations in the proband.Mutation screening was also performed for NPHS1,NPHS2,CD2AP,WTI,TRPC6 and ACTN4 to exclude familial FSGS.Mutation or polymorphism found in the family were examined in 50 healthy controls. Results In this family hematuria segregated with the 55224 haplotype at the COL4A3/COL4A4 locus.G to A substitution at nucleotide 1214 resulting in an glycine being replaced by glutamate (G405E) was demonstrated for the first time in cxon 20 of COL4A4 gene.G4OSE was present in all four members of the family with hematuria but not in the seven unaffected family members nor in 50 healthy controls.A novel polymorphism segregating with hematuria (IVS1-4C＞T in exon 2 ofCOL4A3) was also found which was only present in all four affected family members but not in the seven unaffected family members. No mutations were demonstrated in FSGS associated genes,however,a novel SNP (R268Q),which distributed with the disease ineompletely,was described in the NPHS1 gene coding nephrin,the podocyte slit diaphragm protein. Conclusions In this family,FSGS occurres on the basis of TBMN.Maybe the particular COL4A3/COL4A4 mutation and polymorphism work together to develop proteinuria and eventually leading to FSGS.But whether the mutation and the polymorphism segregating with the disease predispose to develop FSGS in TBMN patients is required further study.

The clinicopathological characteristics of thin basement membrane nephropathy with proteinuria in adult / 대한내과학회지

BACKGROUND: Proteinuria is rarely observed in patients who suffer from thin basement membrane nephropathy (TBMN). Our study was performed to evaluate the clinical characteristics and prognosis of TBMN patients with proteinuria. METHODS: We conducted a retrospective study on 231 kidney biopsies. A urine protein level more than 500 mg for the 24-hour urine excretion was considered as significant proteinuria. We studied the clinical characteristics, the pathological findings and the response to treatment of these patients. RESULTS: Ten (4 males and 6 females) of 17 cases of TBMN had significant proteinuria (59%). The mean patient age was 35 years. Six patients had hypertension and 1 patient had nephrotic syndrome. Two patients had proteinuria only, and 8 patients had both hematuria and proteinuria. At the time of biopsy, the amount of urine protein was 1,881 mg per day, and all the patients except one showed normal renal function. The GBM thickness ranged from 201 to 252 nm. Nine patients were treated with angiotensin receptor blocker, and 1 patient suffering from nephrotic syndrome was treated with prednisolone and cyclophosphamide. Marked improvement of the proteinuria (659 mg per day) was observed in 8 patients during the follow-up period. CONCLUSIONS: Thin basement membrane nephropathy is one of the causes of proteinuria. Therefore, reduction of the proteinuria should be considered for treating these patients.

Progress in the study of thin basement membrane nephropathy / 医学研究生学报

Thin basement membrane nephropathy(TBMN) is one of the most common disorders of the kidney,affecting at least 1% of the population.It seems to be a disease of the adult glomerular basement membrane(GBM) type Ⅳ collagen trimer ?3∶?4∶?5.Genetic evidence indicates that autosomal TBMN is caused by heterozygous mutations in either COL4A3 or COL4A4, whereas homozygous or combined heterozygous mutations in the same genes lead to autosomal recessive Alport syndrome.The author summarized the epidemiology,clinical features,renal biopsy,genetics,pathogenesis,diagnosis and therapy of TBMN.

Two Cases of Thin Basement Membrane Nephropathy presented with Minimal Change Nephrotic Syndrome

Thin basement membrane nephropathy(TBMN) is defined histologically as follows: 1) By light rnicroscopy only minor abnormalities are detected in the glomeruli at most minor mesangial widening. 2) By electron microscopy, diffuse thinning of glomerular basement rnembrane is demonstrated. 3) By immunofluorescence, absence of immunoglobulins and complement components is demonstrated. 4) Alport's syndrome and systemic diseases that may affect the glomerular structure have been excluded. TBMN presented frequently with recurrent or persistent microscopic hematuria. Massive proteinuria such as in nephrotic syndrome rarely occurs in TBMN. We reported two cases of TBMN presented with typical minimal change nephrotic syndrome.