Search

X-linked Alport syndrome (AS) is a heritable disorder which is associated with mutations in the type IV collagen α5(IV) chain gene (COL4AS) located on chromosome X. Following renal transplantation, an average of 6% of male AS patients develop anti-GBM nephritis. We studied the specificity of the antibodies against type IV collagen in the serum of a patient with COL4A5 partial deletion. The specificity of these alloantibodies was determined against collagenasedigested GBM, as well as against recombinant noncollagenous (NCl) domains of the type IV collagen α1(IV)—α6(IV) chains expressed in Escherichia coli. Immunoblotting and ELISA demonstrated that these antibodies bound specifically to the NCl domain of α5(IV) collagen. There was no binding to the NCl domain of the other chains, including the Goodpasture antigen. Competitive ELISA confirmed the results obtained by ELISA and immunoblotting. This patient developed alloantibodies directed against antigens present in the grafted kidney, but absent from his Alport kidney. The pathogenesis of post-transplantation glomerulonephritis in the Alport patient studied is thus similar to that of Goodpasture syndrome, with the exception that the pathogenic antibodies are targeted to another α chain of type IV collagen. [ABSTRACT FROM PUBLISHER]

Alport-type hereditary nephritis is a familial disorder which results in progressive renal insufficiency and sensorineural hearing loss. It is thought to result from a biochemical defect affecting basement membranes. To study this further, non-collagenous components of type IV collagen were prepared from the glomerular basement membrane (GBM) by collagenase digestion from three male patients with hereditary nephritis. The normal Goodpasture antigenicity of the 28 and 26 kD monomers and 54 and 50 kD dimers which may be isolated from the GBM was absent on one-dimensional immunoblots. Two-dimensional electrophoresis and immunoblotting studies showed absence of Goodpasture antigenicity of these molecular weight components as well as all cationic monomeric and dimeric spots. It is concluded that the expression of the Goodpasture antigen is altered in basement membranes of hereditary nephritis patients. The altered antigenicity thus acts as a marker for the underlying abnormality. [ABSTRACT FROM PUBLISHER]

Introduction: Since 2016, kidney transplantation in patients with atypical hemolytic uremic syndrome (aHUS) in the Netherlands is performed without eculizumab prophylaxis. Eculizumab is given in case of posttransplant aHUS recurrence. Eculizumab therapy is monitored in the CUREiHUS study., Methods: All participating kidney transplant patients who received eculizumab therapy for a suspected posttransplant aHUS recurrence were evaluated. Overall recurrence rate was monitored prospectively at Radboud University Medical Center., Results: In the period from January 2016 until October 2020, we included 15 (12 females, 3 males; median age 42 years, range 24-66 years) patients with suspected aHUS recurrence after kidney transplantation in this study. The time interval to recurrence showed a bimodal distribution. Seven patients presented early after transplantation (median 3 months, range 0.3-8.8 months), with typical aHUS features: rapid loss of estimated glomerular filtration rate (eGFR) and laboratory signs of thrombotic microangiopathy (TMA). Eight patients presented late (median 46 months, range 18-69 months) after transplantation. Of these, only 3 patients had systemic TMA, whereas 5 patients presented with slowly deteriorating eGFR without systemic TMA. Treatment with eculizumab resulted in improvement or stabilization of eGFR in 14 patients. Eculizumab discontinuation was tried in 7 patients; however, it was successful only in 3. At the end of the follow-up (median 29 months, range 3-54 months after start of eculizumab), 6 patients had eGFR <30 ml/min per 1.73 m 2 . Graft loss had occurred in 3 of them. Overall, aHUS recurrence rate without eculizumab prophylaxis was 23%., Conclusions: Rescue treatment of posttransplant aHUS recurrence is effective; however, some patients suffer from irreversible loss of kidney function, likely caused by delayed diagnosis and treatment and/or too aggressive discontinuation of eculizumab. Physicians should be aware that recurrence of aHUS can present without evidence of systemic TMA., (© 2023 International Society of Nephrology. Published by Elsevier Inc.)

Defective control of the alternative route of the complement system is an important cause of the non-diarrhoea haemolytic uraemic syndrome (HUS). On the endothelial surface, mutations in HF1, MCP and IF predispose to development ofHUS. Uncontrolled complement activation on the surface of endothelial cells will damage these cells extensively. Plasmapheresis can be an effective, although temporary, treatment for mutations in HF1 and IF. HUS frequently recurs after renal transplantation in patients with HF1 or IF mutations but not in patients with a mutation of MCP. These genetic defects can be detected by routine diagnostics.

Dermatan sulfate (DS) is a member of the glycosaminoglycan (GAG) family and is primarily located in the extracellular matrix. Using a modified phage display procedure, we selected 2 different antibodies against DS of which one antibody, LKN1, was specific for DS. LKN1 was especially reactive with 4/2,4-di-O-sulfated DS, and did not react with other classes of GAGs including chondroitin sulfate and heparan sulfate. Immunohistochemical analysis of kidney, skin and tendon showed a typical fibrillar staining pattern, co-localizing with type I collagen. Staining was abolished by specific enzymatic digestion of DS. Immunoelectron microscopy confirmed the association of the DS epitope with collagen fibrils. The location of DS did not follow the main banding period of collagen, which is in line with the current concept that the core protein rather than the DS moiety of DS-proteoglycans specifically binds to collagen fibrils. This unique anti-DS antibody and the availability of its coding DNA may be instrumental in studies of the structure and function of DS.

In a 17-year-old woman with absent sexual development and a congenital nephrotic syndrome leading to renal failure, the Denys-Drash syndrome was diagnosed after development of an ovarian dysgerminoma. The Denys-Drash syndrome is characterised by the triad: progressive nephropathy due to diffuse mesangial sclerosis, male pseudo-hermaphroditism (XY karyotype with ambiguous or female genital organs) and an increased risk of developing Wilms' tumour and gonadoblastoma. The syndrome is generally caused by a genetic defect in the Wilms' tumour suppressor 1 gene (WT1 gene). A WT1 mutation and XY karyotype were also found in this patient. The WT1 gene encodes a transcription factor playing an important role in renal and genital development. The diagnosis of Denys-Drash syndrome had important consequences for the follow-up and treatment of the patient. The second gonad and the native kidneys were removed due to the increased risk of malignancy. Moreover, the finding of a XY karyotype could result in serious psychic problems. Physicians responsible for the health of adults are confronted more and more often with the consequences of childhood diseases. This case illustrates the necessity to inform such physicians about previously untreatable genetic diseases of childhood so that the adequate medical management of these patients can be guaranteed.

Background: Familial forms of steroid-resistant nephrotic syndrome with the histologic findings of focal-segmental glomerulosclerosis have frequently a genetic basis. For the non-familial forms this is still unresolved., Patients and Methods: Ten children with non-familial steroid-resistant nephrotic syndrome along with focal-segmental glomerulosclerosis were tested for mutations in the WT-1 and NPHS2 genes., Results: In 1 patient, a mutation in intron 9 of the WT-1 gene and in 1 patient a heterozygous NPHS2 mutation could be detected. Both abnormalities are important for the treatment modalities and prognosis., Conclusion: Additional studies will have to provide a solid basis for the recommendation of mutation analysis in non-familial steroid-resistant focal-segmental glomerulosclerosis.

Complex I is the first and largest enzyme of the oxidative phosphorylation system. It consists of at least 43 subunits. Recent studies have shown that the NDUFS4 subunit of complex I contributes to the activation of the complex through cAMP dependent phosphorylation of a conserved site (RVS) located at the C-terminal region of this protein. This report focuses on the NDUFS4 subunit. Summarized is the current knowledge of this subunit, from gene structure to function and pathology.