Frequency and pathohistological characteristics of focal segmental glomerulosclerosis combined with thin basement membranes nephropathy

Mutacije gena odgovornih za sintezu α3, α4 i α5 lanaca kolagena IV uzrokuju spektar poremećaja, od nefropatije tankih glomerularnih bazalnih membrana (TBMN) do X vezanih i autosomnih oblika Alportovog sindroma (AS). Kod određenog broja pacijenata s TBMN-om se primijetilo da s vremenom bolest progredira u kronično bubrežno zatajenje (CRF) uslijed nastanka fokalne segmentalne glomeruloskleroze (FSGS). Zbog toga sve više raste interes za istraživanje povezanosti FSGS-a i navedenih mutacija. Kako je TBMN autosomno dominantni poremećaj uzrokovan mutacijom gena za α3 i/ili α4 lance kolagena IV, nije jasno jesu li neke druge mutacije na istim genima odgovorne za sekundarnu pojavu FSGS-a kod pacijenata s TBMN-om ili se radi o nekoj drugoj, za sada nepoznatoj, mutaciji drugih gena. U sklopu projekta ''Genotip-fenotip korelacija u Alportovom sindromu i nefropatiji tankih glomerularnih bazalnih membrana'', provedeno je retrospektivno istraživanje 30 pacijenata s dijagnozom FSGS-a i nalazom TBMN-a na elektronskoj mikroskopiji (EM). Cilj ovog istraživanja bio je utvrditi prisutnost poremećaja ekspresije α3, α4 i α5 lanaca kolagena IV na imunohistokemiji kod pacijenata s dijagnozom FSGS-a i TBMN-a. S obzirom da su svi analizirani uzorci imali uredne obrasce imunohistokemijskog bojanja lanaca kolagena IV, ne možemo imunohistokemijski utvrditi da je u analiziranim slučajevima FSGS posljedica mutacija gena za lance kolagena IV. Tome u prilog ide i činjenica da niti u jednom slučaju nije bilo pozitivne obiteljske anamneze za AS ili TBMN. Stoga je u analiziranih pacijenata potrebno provesti dodatno genetsko testiranje na mutacije za α3, α4 i α5 lance kolagena IV, što je i idući cilj spomenutog projekta.Recent research shows that mutations of genes indispensable for collagen IV chains synthesis cause a spectrum of disease, ranging from thin basement membrane nephropathy (TBMN) to X-linked and autosomal forms of Alport's syndrome (AS). It was noticed that some patients with TBMN at later age progress to chronic renal failure (CRF) due to the development of focal segmental glomerulosclerosis (FSGS). Therefore the interest in researching the association between FSGS and listed mutations is growing. Since TBMN is an autosomal dominant disorder caused by mutations of genes for α3 and α4 chains of collagen IV, it is not clarified wheter secondary development of FSGS in patients with TBMN is caused by some other mutations of those genes or some other, yet unknow, mutation of other genes. As part of the project ''Genotype-Phenotype correlation in Alport's syndrome and thin basement membrane nephropathy'', we performed a retrospective research of 30 patients with diagnosis of FSGS and finding of TBMN on electron microscopy (EM). The aim of this study is to affirm the irregular expression of α3, α4 and α5 chains of collagen IV on imunohistochemistry in patients with diagnosis of FSGS and TBMN. Since all samples have neat patterns of immunohistochemical staining of collagen IV chains, it cannot be established with certainty that in all cases was FSGS the result of mutations of genes for collagen IV chains. This is also supported by the fact that in none of the cases was family history positive for AS or TBMN. Therefore, the additional genetic testing for mutations of genes for α3, α4 and α5 chains of collagen IV is also required, which is the next step of the mentioned project

Clinical and pathohistological characteristics of Alport spectrum disorder caused by COL4A4 mutation c.193-2A>C: a case series

Aim To present the pathohistological and clinical charac - teristics of five Croatian families with Alport spectrum dis - orders caused by splice acceptor pathogenic variant c.193- 2A>C in COL4A4 at the genomic position chr2:227985866. Methods The study enrolled five probands with kidney bi - opsy analysis and five family members. Mutation screening was performed with Illumina MiSeq platform. The patho - genic variant was confirmed with standard dye-terminator sequencing. Results The only homozygous patient, aged two, had pro - teinuria and hematuria with preserved kidney function and no extrarenal manifestations. This patient had chang - es characteristic for Alport syndrome observed on elec - tron microscopy of the kidney biopsy. In the heterozygous group, six patients had hematuria, four biopsied probands had proteinuria, and only one had moderately reduced kidney function. Heterozygous probands had variable kid - ney biopsy findings. Three patients had thin glomerular basement membrane nephropathy visible on electron mi - croscopy and focal segmental glomerulosclerosis on light microscopy, two of them with focal lamellation on elec - tron microscopy. One heterozygous patient had changes characteristic for Alport syndrome on electron microscopy without focal segmental glomerulosclerosis. Conclusion The homozygous patient had hematuria and proteinuria with preserved kidney function. The heterozy - gous patients presented with reasonably mild clinical phe - notype and variable pathohistological findings

Clinical and histopathological characteristics of COL4A3 c.2881+1G>A variant causing Alport spectrum disorders in Croatian population

Alport syndrome (AS) and thin basement membrane nephropathy (TBMN) are part of the spectrum of kidney disorders caused by pathogenic variants in α3, α4, or α5 chains of the collagen type IV, the major structural component of the glomerular basement membrane (GBM). Using targeted next-generation sequencing (NGS), 34 AS/TBMN patients (58.8% male) from 12 unrelated families were found positive for heterozygous c.2881+1G>A variant of the COL4A3gene, that is considered disease-causing. All patients were from the continental or island part of Croatia. Clinical, laboratory, and histopathological data collected from the medical records were analyzed and compared to understand the clinical course and prognosis of the affected patients. At the time of biopsy or first clinical evaluation, the mean age was 31 years (median: 35 years; range: 1 – 72 years). Hematuria was present in 33 patients (97.1%) and 19 (55.9%) patients had proteinuria. There were 6 (17.6%) patients with hearing loss, 4 (11.8%) with ocular lesions, and 11 (32.4%) with hypertension. Twenty-three (67.6%) patients had proteinuria at follow-up, and 5 (14.7%) patients with the median age of 48 years (range: 27-55) progressed to kidney failure, started dialysis, or underwent kidney transplantation. Of the 13 patients who underwent kidney biopsy, 4 (30.8%) developed focal segmental glomerulosclerosis (FSGS), and 8 (66.7%) showed lamellation of the GBM, including all patients with FSGS. It is essential to conduct a detailed analysis of each collagen type IV genetic variant to optimize the prognosis and therapeutic approach for affected patients

Characteristics of patients with thin basement membrane nephropathy combined with focal segmental glomerulosclerosis

Svrha rada: Svrha ovog istraživanja je bila provesti sekvenciranje gena COL4A3, COL4A4 i COL4A5 NGS metodom u bolesnika s TBMN-om sa ili bez FSGS-a, a potom analizirati prikupljene genske, kliničke i histološke podatke i provesti genotip-fenotip korelaciju. Ispitanici i metode: Bolesnici su identificirani pretragom registra bubrežnih biopsija Odjela za nefropatologiju i elektronsku mikroskopiju Kliničke bolnice Dubrava te podijeljeni u dvije skupine: 1. bolesnici s TBMN-om i 2. bolesnici s FSGS-om i TBMN-om. Nakon identifikacije prikupljeni su svi dostupni klinički i patohistološki podaci, provedeno je mjerenje debljine GBM, a bolesnicima je uzet uzorak krvi za NGS. Dobiveni rezultati i prikupljeni podaci su analizirani te je provedena genotip-fenotip korelacija. Rezultati: Sekvenciranjem je u 52 % bolesnika nađena patogena varijanta, a u 10 % VUS. Bolesnici s FSGS-om i TBMN-om u odnosu na bolesnike samo s TBMN-om imaju statistički značajno izraženije kliničke simptome i znakove, morfološke promjene te komorbiditete. Nije nađena statistički značajna razlika u patogenosti i tipu varijante između skupine bolesnika s FSGS-om i TBMN-om i skupine s TBMN-om. Zaključak: Bolesnici s FSGS-om i TBMN-om u odnosu na bolesnike samo s TBMN-om imaju izraženije kliničke simptome i morfološke promjene na bioptičkim uzorcima.Objective: The aim of this research was to perform sequencing of the COL4A3, COL4A4 and COL4A5 genes with NGS in patients with TBMN with or without FSGS, then to analyze the genetic, clinical and pathohistological data and perform genotype-phenotype correlation. Patients and methods: The patients were identified by searching the kidney biopsy register of the Department of Nephropathology and Electron Microscopy of Dubrava University Hospital and divided into two groups: 1. patients with TBMN and 2. patients with FSGS and TBMN. Patients' clinical and pathohistological data were collected, GBM thickness was measured, and a blood sample was taken for NGS. The results and collected data were analyzed and genotype-phenotype correlation was performed. Results: Sequencing detected a pathogenic variant in 52 % and VUS in 10 % of patients. Patients with FSGS and TBMN compared to patients with only TBMN have significantly more pronounced clinical symptoms and signs, morphological changes and comorbidities. No statistically significant difference was found in pathogenicity and variant type between the group of patients with FSGS and TBMN and the group with TBMN. Conclusion: Patients with FSGS and TBMN have more severe clinical course and morphological changes on biopsy samples than patients with only TBMN

Characteristics of patients with thin basement membrane nephropathy combined with focal segmental glomerulosclerosis

Svrha rada: Svrha ovog istraživanja je bila provesti sekvenciranje gena COL4A3, COL4A4 i COL4A5 NGS metodom u bolesnika s TBMN-om sa ili bez FSGS-a, a potom analizirati prikupljene genske, kliničke i histološke podatke i provesti genotip-fenotip korelaciju. Ispitanici i metode: Bolesnici su identificirani pretragom registra bubrežnih biopsija Odjela za nefropatologiju i elektronsku mikroskopiju Kliničke bolnice Dubrava te podijeljeni u dvije skupine: 1. bolesnici s TBMN-om i 2. bolesnici s FSGS-om i TBMN-om. Nakon identifikacije prikupljeni su svi dostupni klinički i patohistološki podaci, provedeno je mjerenje debljine GBM, a bolesnicima je uzet uzorak krvi za NGS. Dobiveni rezultati i prikupljeni podaci su analizirani te je provedena genotip-fenotip korelacija. Rezultati: Sekvenciranjem je u 52 % bolesnika nađena patogena varijanta, a u 10 % VUS. Bolesnici s FSGS-om i TBMN-om u odnosu na bolesnike samo s TBMN-om imaju statistički značajno izraženije kliničke simptome i znakove, morfološke promjene te komorbiditete. Nije nađena statistički značajna razlika u patogenosti i tipu varijante između skupine bolesnika s FSGS-om i TBMN-om i skupine s TBMN-om. Zaključak: Bolesnici s FSGS-om i TBMN-om u odnosu na bolesnike samo s TBMN-om imaju izraženije kliničke simptome i morfološke promjene na bioptičkim uzorcima.Objective: The aim of this research was to perform sequencing of the COL4A3, COL4A4 and COL4A5 genes with NGS in patients with TBMN with or without FSGS, then to analyze the genetic, clinical and pathohistological data and perform genotype-phenotype correlation. Patients and methods: The patients were identified by searching the kidney biopsy register of the Department of Nephropathology and Electron Microscopy of Dubrava University Hospital and divided into two groups: 1. patients with TBMN and 2. patients with FSGS and TBMN. Patients' clinical and pathohistological data were collected, GBM thickness was measured, and a blood sample was taken for NGS. The results and collected data were analyzed and genotype-phenotype correlation was performed. Results: Sequencing detected a pathogenic variant in 52 % and VUS in 10 % of patients. Patients with FSGS and TBMN compared to patients with only TBMN have significantly more pronounced clinical symptoms and signs, morphological changes and comorbidities. No statistically significant difference was found in pathogenicity and variant type between the group of patients with FSGS and TBMN and the group with TBMN. Conclusion: Patients with FSGS and TBMN have more severe clinical course and morphological changes on biopsy samples than patients with only TBMN

Frequency and pathohistological characteristics of focal segmental glomerulosclerosis combined with thin basement membranes nephropathy

Mutacije gena odgovornih za sintezu α3, α4 i α5 lanaca kolagena IV uzrokuju spektar poremećaja, od nefropatije tankih glomerularnih bazalnih membrana (TBMN) do X vezanih i autosomnih oblika Alportovog sindroma (AS). Kod određenog broja pacijenata s TBMN-om se primijetilo da s vremenom bolest progredira u kronično bubrežno zatajenje (CRF) uslijed nastanka fokalne segmentalne glomeruloskleroze (FSGS). Zbog toga sve više raste interes za istraživanje povezanosti FSGS-a i navedenih mutacija. Kako je TBMN autosomno dominantni poremećaj uzrokovan mutacijom gena za α3 i/ili α4 lance kolagena IV, nije jasno jesu li neke druge mutacije na istim genima odgovorne za sekundarnu pojavu FSGS-a kod pacijenata s TBMN-om ili se radi o nekoj drugoj, za sada nepoznatoj, mutaciji drugih gena. U sklopu projekta ''Genotip-fenotip korelacija u Alportovom sindromu i nefropatiji tankih glomerularnih bazalnih membrana'', provedeno je retrospektivno istraživanje 30 pacijenata s dijagnozom FSGS-a i nalazom TBMN-a na elektronskoj mikroskopiji (EM). Cilj ovog istraživanja bio je utvrditi prisutnost poremećaja ekspresije α3, α4 i α5 lanaca kolagena IV na imunohistokemiji kod pacijenata s dijagnozom FSGS-a i TBMN-a. S obzirom da su svi analizirani uzorci imali uredne obrasce imunohistokemijskog bojanja lanaca kolagena IV, ne možemo imunohistokemijski utvrditi da je u analiziranim slučajevima FSGS posljedica mutacija gena za lance kolagena IV. Tome u prilog ide i činjenica da niti u jednom slučaju nije bilo pozitivne obiteljske anamneze za AS ili TBMN. Stoga je u analiziranih pacijenata potrebno provesti dodatno genetsko testiranje na mutacije za α3, α4 i α5 lance kolagena IV, što je i idući cilj spomenutog projekta.Recent research shows that mutations of genes indispensable for collagen IV chains synthesis cause a spectrum of disease, ranging from thin basement membrane nephropathy (TBMN) to X-linked and autosomal forms of Alport's syndrome (AS). It was noticed that some patients with TBMN at later age progress to chronic renal failure (CRF) due to the development of focal segmental glomerulosclerosis (FSGS). Therefore the interest in researching the association between FSGS and listed mutations is growing. Since TBMN is an autosomal dominant disorder caused by mutations of genes for α3 and α4 chains of collagen IV, it is not clarified wheter secondary development of FSGS in patients with TBMN is caused by some other mutations of those genes or some other, yet unknow, mutation of other genes. As part of the project ''Genotype-Phenotype correlation in Alport's syndrome and thin basement membrane nephropathy'', we performed a retrospective research of 30 patients with diagnosis of FSGS and finding of TBMN on electron microscopy (EM). The aim of this study is to affirm the irregular expression of α3, α4 and α5 chains of collagen IV on imunohistochemistry in patients with diagnosis of FSGS and TBMN. Since all samples have neat patterns of immunohistochemical staining of collagen IV chains, it cannot be established with certainty that in all cases was FSGS the result of mutations of genes for collagen IV chains. This is also supported by the fact that in none of the cases was family history positive for AS or TBMN. Therefore, the additional genetic testing for mutations of genes for α3, α4 and α5 chains of collagen IV is also required, which is the next step of the mentioned project

Characteristics of patients with thin basement membrane nephropathy combined with focal segmental glomerulosclerosis

Svrha rada: Svrha ovog istraživanja je bila provesti sekvenciranje gena COL4A3, COL4A4 i COL4A5 NGS metodom u bolesnika s TBMN-om sa ili bez FSGS-a, a potom analizirati prikupljene genske, kliničke i histološke podatke i provesti genotip-fenotip korelaciju. Ispitanici i metode: Bolesnici su identificirani pretragom registra bubrežnih biopsija Odjela za nefropatologiju i elektronsku mikroskopiju Kliničke bolnice Dubrava te podijeljeni u dvije skupine: 1. bolesnici s TBMN-om i 2. bolesnici s FSGS-om i TBMN-om. Nakon identifikacije prikupljeni su svi dostupni klinički i patohistološki podaci, provedeno je mjerenje debljine GBM, a bolesnicima je uzet uzorak krvi za NGS. Dobiveni rezultati i prikupljeni podaci su analizirani te je provedena genotip-fenotip korelacija. Rezultati: Sekvenciranjem je u 52 % bolesnika nađena patogena varijanta, a u 10 % VUS. Bolesnici s FSGS-om i TBMN-om u odnosu na bolesnike samo s TBMN-om imaju statistički značajno izraženije kliničke simptome i znakove, morfološke promjene te komorbiditete. Nije nađena statistički značajna razlika u patogenosti i tipu varijante između skupine bolesnika s FSGS-om i TBMN-om i skupine s TBMN-om. Zaključak: Bolesnici s FSGS-om i TBMN-om u odnosu na bolesnike samo s TBMN-om imaju izraženije kliničke simptome i morfološke promjene na bioptičkim uzorcima.Objective: The aim of this research was to perform sequencing of the COL4A3, COL4A4 and COL4A5 genes with NGS in patients with TBMN with or without FSGS, then to analyze the genetic, clinical and pathohistological data and perform genotype-phenotype correlation. Patients and methods: The patients were identified by searching the kidney biopsy register of the Department of Nephropathology and Electron Microscopy of Dubrava University Hospital and divided into two groups: 1. patients with TBMN and 2. patients with FSGS and TBMN. Patients' clinical and pathohistological data were collected, GBM thickness was measured, and a blood sample was taken for NGS. The results and collected data were analyzed and genotype-phenotype correlation was performed. Results: Sequencing detected a pathogenic variant in 52 % and VUS in 10 % of patients. Patients with FSGS and TBMN compared to patients with only TBMN have significantly more pronounced clinical symptoms and signs, morphological changes and comorbidities. No statistically significant difference was found in pathogenicity and variant type between the group of patients with FSGS and TBMN and the group with TBMN. Conclusion: Patients with FSGS and TBMN have more severe clinical course and morphological changes on biopsy samples than patients with only TBMN

Immune-mediated diseases after coronavirus disease 2019 vaccination: rare but important complication

Since the beginning of mass vaccination against coronavirus disease 2019 (COVID-19), vaccine-linked immune-mediated diseases have been increasingly reported. The development of these diseases after COVID-19 vaccination may be attributed to the mechanisms of molecular mimicry and cross-reactivity between the viral spike protein and self-antigens. The most frequent vaccine-linked glomerular disease is immunoglobulin A nephropathy (IgAN). Cutaneous vasculitis has also been reported after COVID-19 vaccination. In both diseases, deposition of immune complexes activates the inflammatory response with end-organ damage. We report on a case of de novo IgAN in a young man and a case of severe cutaneous vasculitis in a 68-year-old woman, both after the second dose of Pfizer-BioNTech COVID-19 vaccine. Neither of the patients had a history of autoimmunity or adverse reactions to vaccines. The temporal association between vaccination and disease development in the absence of other possible intercurrent inciting events suggests a causal mechanism, although coincidental co-occurrence cannot be excluded. In both cases, immunosuppressive treatment was warranted to stop disease progression and to partially or completely resolve the disease. A timely reaction is needed if new-onset signs of an immune-mediated disease appear after vaccination

Clinical Significance of Zero-Time Renal Transplant Biopsies and Thin Glomerular Basement Membranes in Zero-Time Renal Transplant Biopsies

Cilj. Ispitati morfološke karakteristike nultih biopsija bubrega analiziranih na Odjelu za nefropatologiju i elektronsku mikroskopiju Kliničke bolnice Dubrava, Zagreb. ----- Materijali i metode. Retrospektivno pretraživanje podataka provedeno je za razdoblje od 2006. do 2018. godine. Analizirano je ukupno 316 nultih biopsija bubrega. Debljina glomerularne bazalne membrane (GBM) ponovno je izmjerena u 84 nulte i 80 protokolarnih biopsija istih pacijenata 12 mjeseci nakon transplantacije. ----- Rezultati i zaključak. Akutno tubularno oštećenje bilo je prisutno u 90% nultih biopsija, a u 17% biopsija pronađena je glomerularna patologija, od toga je najčešći entitet bio tanke bazalne mebrane (TBM ) (13%). Kronične promjene presatka procijenjene su prema Banff klasifikaciji. Većina slučajeva pokazala je Banff skorove ci0 (82,6%) i ct0 (65,1%). Banff skorovi cv2 i cv3 bili su prisutni u 13%, a ah2 i ah3 u 36,4% uzoraka. Među 84 ponovno izmjerenih nultih biopsija TBM su bile prisutne u 26 pacijenata (31%). Nije bilo razlika između Banff skorova i kliničkih parametara 12 mjeseci nakon transplantacije između primatelja s TBM i primatelja s normalnom debljinom GBM. Nulte biopsije bubrega su iznimno važne za procjenu presatka i usporedbu s kasnijim protokolarnim biopsijama. Kako bi se utvrdio dugoročni značaj TBM -a na preživljavanje presatka potrebna su dodatna istraživanja.Aim. To investigate morphological findings of zero-time biopsies analyzed at the Department of Nephropathology and Electron Microscopy, Dubrava University Hospital, Zagreb. ----- Materials and methods. The retrospective search of data was performed for the period from 2006 to 2018. A total of 316 zero-time renal biopsies were analyzed. Glomerular basement membrane (GBM) thickness was remeasured in 84 zero-time biopsies and 80 protocol biopsies of the same patients 12 months after transplantation. ----- Results and conclusion. The acute tubular injury was present in 90% and glomerular pathology in 17% of zero-time biopsies, with thin basement membranes (TBM ) being the most common entity (13%). Chronic graft changes were evaluated according to Banff classification. Most cases showed Banff scores ci0 (82.6%) and ct0 (65.1%). Banff scores cv2 and cv3 were present in 13% and ah2 and ah3 in 36.4% of specimens. Among 84 remeasured zero-time samples, TBM was present in 26 patients (31%). There were no differences between Banff scores and clinical parameters 12 months after transplantation between recipients with TBM and recipients with normal GBM thickness. Zero-time renal biopsy is of great importance for allograft assessment and comparison with consecutive biopsies. Further investigation is needed to determine the long-term significance of TBM on graft survival

Resistant and Relapsing Collapsing Glomerulopathy Successfully Treated with Rituximab—A Case Report

Collapsing glomerulopathy (CG) or collapsing focal segmental glomerulosclerosis (cFSGS) is an aggressive disease with a high tendency of progression to end-stage renal disease due to common resistance to conventional immunosuppressants. Rituximab (RTX), a monoclonal antibody against CD20 B cells, showed some benefit in the treatment of CG. We are reporting about female patients with an idiopathic form of CG presenting with nephrotic syndrome (NS) and renal insufficiency resistant to several immunosuppressive agents such as steroids (ST), calcineurin inhibitors (CNI), and cyclophosphamide (CYC). This multidrug-resistant disease responded to RTX with complete remission. Forty-four months after initial RTX administration, a relapse of CG with severe NS and acute renal insufficiency occurred. Repeated application of RTX led to complete remission again. To the best of our knowledge, we are reporting the first case of the relapsing multidrug-resistant form of CG, which responded to RTX. Current data about the treatment of CG with RTX is lacking and is based on rare case reports and small case series. Thus, our report can contribute to determining the role of RTX in the treatment of CG