Abdullah H Almalki, Laila F Sadagah, Mohammed Qureshi, Hatim Maghrabi, Abdulrahman Algain, Ahmed Alsaeed CASE REPORT 243 November 6, 2017|Volume 6|Issue 6| WJN|www.wjgnet.com Atypical hemolytic-uremic syndrome due to complement factor I mutation World Journal of Nephrology WJN Submit a Manuscript: http://www.f6publishing.com DOI: 10.5527/wjn.v6.i6.243 World J Nephrol 2017 November 6; 6(6): 243-250 ISSN 2220-6124 (online) Abdullah H Almalki, Laila F Sadagah, Mohammed Qureshi, Hatim Maghrabi, Abdulrahman Algain, Ahmed Alsaeed, King Abdulaziz Medical City, Ministry of National Guard, Jeddah 21423, Saudi Arabia Abdullah H Almalki, Hatim Maghrabi, Ahmed Alsaeed, King Saud Bin Abdulaziz University for Health Sciences, Ministry of National Guard, Jeddah 21423, Saudi Arabia ORCID number: Abdullah H Almalki (0000-0003-1885-3709); Laila F Sadagah (0000-0002-0133-8615); Mohammed Qureshi (0000-0002-8855-6585); Hatim Maghrabi (0000-0002-0074-2245); Abdulrahman Algain (0000-0002-9886-4477); Ahmed Alsaeed (0000-0003-1711-7031). Author contributions: Almalki AH carried out literature search, wrote the abstract and discussion, and revised and aligned the whole manuscript; Sadagah LF conducted independent literature search and wrote the background; Algain A collected clinical information and wrote the initial case description; Qureshi M revised all collected clinical information and wrote the fnal case description and the draft of the abstract; Maghrabi H prepared the slides, provided histological description, and aided in writing the case description; Alsaeed A carried out independent search on hematologic literature and revised and edited the discussion; all authors read and approved the fnal manuscript. Institutional review board statement: This case report was exempt from the Institutional Review Board standards at King Abdulaziz International Medical Research Centre. Informed consent statement: The patient involved in this study gave written informed consent authorizing the use and disclosure of her clinical data. Confict-of-interest statement: All authors have no confict of interest to declare. Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/ licenses/by-nc/4.0/ Manuscript source: Unsolicited manuscript Correspondence to: Abdullah H Almalki, Section Head, Department of Medicine, King Abdulaziz Medical City, Western Region, PO Box 9515, Jeddah 21423, Saudi Arabia. malkia02@ngha.med.sa Telephone: +966-12-2266666 Fax: +966-2-2266200 Received: June 27, 2017 Peer-review started: June 28, 2017 First decision: September 4, 2017 Revised: September 12, 2017 Accepted: November 1, 2017 Article in press: November 1, 2017 Published online: November 6, 2017 Abstract Atypical hemolytic-uremic syndrome (aHUS) is a rare disease of complement dysregulation leading to thrombotic microangiopathy (TMA). Renal involvement and progression to end-stage renal disease are common in untreated patients. We report a 52-year- old female patient who presented with severe acute kidney injury, microangiopathic hemolytic anemia, and thrombocytopenia. She was managed with steroid, plasma exchange, and dialysis. Kidney biopsy shows TMA and renal cortical necrosis. Genetic analysis reveals heterozygous complement factor Ⅰ (CFI) mutation. Eculizumab was initiated after 3 mo of presentation, continued for 9 mo, and stopped because of sustained hematologic remission, steady renal function, and cost issues. Despite this, the patient continued to be in hematologic remission and showed signs of renal recovery, and peritoneal dialysis was stopped 32 mo