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Background: The cause of chronic kidney disease (CKD) remains unknown in ∼20% of patients with kidney failure. Massively parallel sequencing (MPS) can be a valuable diagnostic tool in patients with unexplained CKD, with a diagnostic yield of 12%-56%. Here, we report the use of MPS to establish a genetic diagnosis in a 24-year-old index patient who presented with hypertension, nephrotic-range proteinuria and kidney failure of unknown origin. Additionally, we describe a second family with the same mutation presenting with early-onset CKD., Results: In Family 1, MPS identified a known pathogenic variant in GLA (p.Ile319Thr), and plasma globotriaosylsphingosine and α-galactosidase A activity were compatible with the diagnosis of Fabry disease (FD). Segregation analysis identified three other family members carrying the same pathogenic variant who had mild or absent kidney phenotypes. One family member was offered enzyme therapy. While FD could not be established with certainty as the cause of kidney failure in the index patient, no alternative explanation was found. In Family 2, the index patient had severe glomerulosclerosis and a kidney biopsy compatible with FD at the age of 30 years, along with cardiac involvement and a history of acroparesthesia since childhood, in keeping with a more classical Fabry phenotype., Conclusion: These findings highlight the large phenotypic heterogeneity associated with GLA mutations in FD and underline several important implications of MPS in the work-up of patients with unexplained kidney failure., Competing Interests: N.V.A.M.K. reports a grant from Health Holland. L.V. reports consulting fees (all to employer) from Sanofi Genzyme. M.H.d.B. reports honoraria (all to employer) from Amgen, AstraZeneca, Bayer, Kyowa Kirin Pharma, Pharmacosmos, Sanofi Genzyme and Vifor Pharma, and grants from Sanofi Genzyme and Health Holland (grant numbers RVO/6320 and IMAGEN/LSHM20009). The other authors declare no competing interest., (© The Author(s) 2022. Published by Oxford University Press on behalf of the ERA.)

Background and Objectives: Cyclophosphamide has been the mainstay of treatment of ANCA-associated vasculitis. However, cyclophosphamide has unfavorable side effects and alternatives are needed. Evidence suggests that mycophenolate mofetil can induce sustained remission in nonlife-threatening disease. The purpose of this study was to compare the efficacy and safety of mycophenolate mofetil versus cyclophosphamide for the induction treatment of nonlife-threatening relapses of proteinase 3-ANCA- and myeloperoxidase-ANCA-associated vasculitis., Design, Setting, Participants, & Measurements: We conducted a multicenter randomized, controlled trial. Participants with a first or second relapse of ANCA-associated vasculitis were randomized to induction treatment with cyclophosphamide or mycophenolate mofetil both in combination with glucocorticoids. Maintenance therapy consisted of azathioprine in both arms. Primary outcome was remission at 6 months, and secondary outcomes included disease-free survival at 2 and 4 years., Results: Eighty-four participants were enrolled, of whom 41 received mycophenolate mofetil and 43 received cyclophosphamide. Eighty-nine percent of participants were proteinase 3-ANCA positive. At 6 months, 27 (66%) mycophenolate mofetil-treated participants versus 35 (81%) cyclophosphamide-treated participants were in remission ( P =0.11). Disease-free survival rates at 2 and 4 years were 61% and 39% for cyclophosphamide, respectively, and 43% and 32% for mycophenolate mofetil, respectively (at 4 years, log rank test, P =0.17)., Conclusions: We did not demonstrate mycophenolate mofetil to be similarly effective as cyclophosphamide in inducing remission of relapsed ANCA-associated vasculitis. However, mycophenolate mofetil might be an alternative to cyclophosphamide for the treatment of selected patients with nonlife-threatening relapses., (Copyright © 2019 by the American Society of Nephrology.)

Background: Cytoplasmic anti-neutrophil cytoplasmic antibody (C-ANCA) positivity at remission has been associated with an increased relapse rate in patients with proteinase 3 anti-neutrophil cytoplasmic antibody-associated vasculitis (PR3-AAV) after a switch to azathioprine maintenance therapy. We therefore hypothesized that extended azathioprine maintenance therapy could reduce the incidence of relapse in this setting., Methods: Patients newly diagnosed with PR3-AAV at 12 centres in The Netherlands during 2003-11 who received a standardized induction regimen consisting of oral cyclophosphamide and corticosteroids were enrolled (n = 131). Patients were randomized to standard or extended azathioprine maintenance therapy when C-ANCA was positive at the time of stable remission. Standard maintenance treatment consisted of azathioprine (1.5-2.0 mg/kg) until 1 year after diagnosis and subsequent tapering to 25 mg every 3 months. Extended azathioprine maintenance therapy (1.5-2.0 mg/kg) was continued until 4 years after diagnosis and tapered thereafter. The primary endpoint was relapse-free survival at 4 years after diagnosis., Results: In patients with PR3-AAV who were C-ANCA positive at the time of stable remission, relapse-free survival at 4 years after diagnosis did not differ significantly between standard azathioprine (n = 24) and extended azathioprine (n = 21) maintenance therapy (P = 0.40). There was also no significant difference in relapse-free survival between patients receiving standard azathioprine (n = 106) versus extended azathioprine maintenance therapy (n = 21; P = 0.94). In addition, there was no difference in the relapse rate between patients with PR3-AAV who were C-ANCA positive (n = 45) at the time of remission versus patients who became C-ANCA negative at the time of remission (n = 82; P = 0.62)., Conclusions: This randomized trial suggests that extended azathioprine maintenance therapy has only a limited effect on the prevention of relapse in patients with PR3-AAV at 4 years after diagnosis. Moreover, positive C-ANCA status at stable remission was not associated with an increased rate of relapse., Trial Registration: ClinicalTrials.gov NCT 00128895., (© The Author 2016. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.)