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Functional characterization of 105 Factor H variants associated with atypical HUS: lessons for variant classification. Blood 2021; 138:2185-2201. [PMID: 34189567 PMCID: PMC8641096 DOI: 10.1182/blood.2021012037] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 06/08/2021] [Indexed: 11/20/2022] Open
Abstract
Atypical hemolytic uremic syndrome (aHUS) is a life-threatening thrombotic microangiopathy that can progress, when untreated, to end-stage renal disease. Most frequently, aHUS is caused by complement dysregulation due to pathogenic variants in genes that encode complement components and regulators. Amongst these genes, the Factor H (FH) gene, CFH, presents with the highest frequency (15-20%) of variants and is associated with the poorest prognosis. Correct classification of CFH variants as pathogenic or benign is essential to clinical care but remains challenging owing to the dearth of functional studies. As a result, significant numbers of variants are reported as variants of uncertain significance. To address this knowledge gap, we expressed and functionally characterized 105 aHUS-associated FH variants. All FH variants were categorized as pathogenic or benign, and for each, we fully documented the nature of the pathogenicity. Twenty-six previously characterized FH variants were used as controls to validate and confirm the robustness of the functional assays used. Of the remaining 79 uncharacterized variants, only 29 (36.7%) alter FH in vitro expression or function and are therefore proposed to be pathogenic. We show that rarity in control databases is not informative for variant classification, and we identify important limitations in applying prediction algorithms to FH variants. Based on structural and functional data, we suggest ways to circumvent these difficulties and thereby improve variant classification. Our work highlights the need for functional assays to interpret FH variants accurately if clinical care of patients with aHUS is to be individualized and optimized.
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Zhang Y, Keenan A, Dai DF, May KS, Anderson EE, Lindorfer MA, Henrich JB, Pitcher GR, Taylor RP, Smith RJ. C3(H2O) prevents rescue of complement-mediated C3 glomerulopathy in Cfh-/- Cfd-/- mice. JCI Insight 2020; 5:135758. [PMID: 32376801 DOI: 10.1172/jci.insight.135758] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 04/01/2020] [Indexed: 11/17/2022] Open
Abstract
Therapeutic complement inhibition is a major focus for novel drug development. Of upstream targets, factor D (FD) is appealing because it circulates in plasma at low concentrations and has a single function: to cleave factor B to generate C3 convertase of the alternative pathway (AP). Mice with a targeted deletion of factor H (FH; Cfh-/- mice) develop C3 glomerulopathy (C3G) due to uncontrolled AP activity. To assess the impact of FD inhibition, we studied Cfh-/- Cfd-/- mice. We show that C3G in Cfh-/- mice is not rescued by removing FD. We used serum from Cfh-/- Cfd-/- mice to demonstrate that residual AP function occurs even when both FD and FH are missing and that hemolytic activity is present due to the action of C3(H2O). We propose that uncontrolled tick-over leads to slow activation of the AP in Cfh-/- Cfd-/- mice and that a minimal threshold of FH is necessary if tissue deposition of C3 is to be prevented. The FD/FH ratio dictates serum C3 level and renal C3b deposition. In C3G patients with chronic renal disease, the FD/FH ratio correlates inversely with C3 and C5 serum levels, suggesting that continuous AP control may be difficult to achieve by targeting FD.
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Affiliation(s)
- Yuzhou Zhang
- Molecular Otolaryngology and Renal Research Laboratories, and
| | - Adam Keenan
- Molecular Otolaryngology and Renal Research Laboratories, and
| | - Dao-Fu Dai
- Department of Pathology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Kristofer S May
- Molecular Otolaryngology and Renal Research Laboratories, and
| | | | - Margaret A Lindorfer
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - John B Henrich
- Molecular Otolaryngology and Renal Research Laboratories, and
| | | | - Ronald P Taylor
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia, USA
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3
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Cavero T, Alonso M. Where are we with haemolytic uremic syndrome? Med Clin (Barc) 2018; 151:329-335. [PMID: 29699703 DOI: 10.1016/j.medcli.2018.02.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 02/06/2018] [Accepted: 02/07/2018] [Indexed: 12/30/2022]
Abstract
Haemolytic uremic syndrome (HUS) is characterised by microangiopathic haemolytic anaemia with acute kidney injury. It is currently classified into two main categories: Shiga-toxin producing E. coli-hemolytic uremic syndrome (STEC-HUS) and atypical haemolytic uremic syndrome (aHUS). Endothelial cell damage is the common pathway in HUS to developing thrombotic microangiopathy. Atypical HUS includes primary, secondary and aHUS due to metabolic diseases. In the majority of aHUS cases, hyperactivity of the alternative complement pathway plays a central role. Therefore, treatment is based on complement inhibitors like eculizumab, a drug that has revolutionised the natural history of the disease. Relapses are frequent after kidney transplant and thus confer a poor prognosis.
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Affiliation(s)
- Teresa Cavero
- Servicio de Nefrología, Hospital 12 de Octubre, Madrid, España.
| | - Marina Alonso
- Servicio de Anatomía Patológica, Hospital 12 de Octubre, Madrid, España
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Salwa-Żurawska W, Żurawski J, Woźniak A, Bortkiewicz E, Burchardt P, Kwiatkowski P, Seget M, Tabaczewski P. Hemolytic-uremic syndrome: Findings of post-acute renal failure in light and electron microscopy. Ultrastruct Pathol 2017; 41:227-233. [PMID: 28296538 DOI: 10.1080/01913123.2017.1292436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The blood count test results of six patients (five male adolescents and one female adult) who were diagnosed with the hemolytic-uremic syndrome are presented. Certain diverse lesions and especially, their different intensity, were observed. They were referred to the clinical process and the time from syndrome occurrence to biopsy.
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Affiliation(s)
- Wiesława Salwa-Żurawska
- a University of Medical Sciences Poznan , Department of Clinical Pathology , Poznań , Poland
| | - Jakub Żurawski
- b University of Medical Sciences Poznan, Department of Biology and Environmental Protection , Division of Immunobiochemistry , Poznań , Poland
| | - Aldona Woźniak
- a University of Medical Sciences Poznan , Department of Clinical Pathology , Poznań , Poland
| | - Elżbieta Bortkiewicz
- c University of Medical Sciences Poznan , Department of Pediatric Cardiology , Poznań , Poland
| | - Paweł Burchardt
- d University of Medical Sciences Poznan , Department of Biology and Environmental Protection , Poznań , Poland
| | | | - Monika Seget
- a University of Medical Sciences Poznan , Department of Clinical Pathology , Poznań , Poland
| | - Piotr Tabaczewski
- b University of Medical Sciences Poznan, Department of Biology and Environmental Protection , Division of Immunobiochemistry , Poznań , Poland.,f University of Miami Miller School of Medicine , Division of Hospital Medicine , Miami , FL, USA
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5
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Cho HJ, Kim JO, Huh JY, Park Y, Kim MG, Oh D. A case of atypical hemolytic uremic syndrome associated with the c.1273C>T mutation in the complement C3 gene. Blood Res 2016; 51:210-213. [PMID: 27722136 PMCID: PMC5054257 DOI: 10.5045/br.2016.51.3.210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 08/21/2015] [Accepted: 09/10/2015] [Indexed: 11/19/2022] Open
Affiliation(s)
- Hye Jeong Cho
- Department of Internal Medicine, School of Medicine, CHA University, Seongnam, Korea
| | - Jung O Kim
- Institute for Clinical Research, Korea University College of Medicine, Seoul, Korea
| | - Ji Young Huh
- Laboratory Medicine, School of Medicine, CHA University, Seongnam, Korea
| | - Yong Park
- Department of Internal Medicine, Korea University College of Medicine, Seoul, Korea
| | - Myung-Gyu Kim
- Department of Internal Medicine, Korea University College of Medicine, Seoul, Korea
| | - Doyeun Oh
- Department of Internal Medicine, School of Medicine, CHA University, Seongnam, Korea
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Cheong HI, Jo SK, Yoon SS, Cho H, Kim JS, Kim YO, Koo JR, Park Y, Park YS, Shin JI, Yoo KH, Oh D. Clinical Practice Guidelines for the Management of Atypical Hemolytic Uremic Syndrome in Korea. J Korean Med Sci 2016; 31:1516-28. [PMID: 27550478 PMCID: PMC4999392 DOI: 10.3346/jkms.2016.31.10.1516] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 07/10/2016] [Indexed: 12/19/2022] Open
Abstract
Atypical hemolytic uremic syndrome (aHUS) is a rare syndrome characterized by micro-angiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. The major pathogenesis of aHUS involves dysregulation of the complement system. Eculizumab, which blocks complement C5 activation, has recently been proven as an effective agent. Delayed diagnosis and treatment of aHUS can cause death or end-stage renal disease. Therefore, a diagnosis that differentiates aHUS from other forms of thrombotic microangiopathy is very important for appropriate management. These guidelines aim to offer recommendations for the diagnosis and treatment of patients with aHUS in Korea. The guidelines have largely been adopted from the current guidelines due to the lack of evidence concerning the Korean population.
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Affiliation(s)
- Hae Il Cheong
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea
- Research Coordination Center for Rare Diseases, Seoul National University Hospital, Seoul, Korea
| | - Sang Kyung Jo
- Division of Nephrology, Department of Internal Medicine, Korea University School of Medicine, Seoul, Korea
| | - Sung Soo Yoon
- Department of Internal Medicine, Seoul National University, Seoul, Korea
| | - Heeyeon Cho
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jin Seok Kim
- Division of Hematology, Department of Internal Medicine, Yonsei University College of Medicine, Severance Hospital, Seoul, Korea
| | - Young Ok Kim
- Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Uijeongbu, Korea
| | - Ja Ryong Koo
- Division of Nephrology, Dongtan Sacred Heart Hospital, Hallym University Medical Center, Hwaseong, Korea
| | - Yong Park
- Division of Hematology, Department of Internal Medicine, Korea University School of Medicine, Seoul, Korea
| | - Young Seo Park
- Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea
| | - Jae Il Shin
- Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Kee Hwan Yoo
- Department of Pediatrics, Korea University Guro Hospital, Seoul, Korea
| | - Doyeun Oh
- Department of Internal Medicine, School of Medicine, CHA University, Seongnam, Korea.
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8
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9
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Cho H. Complement regulation: physiology and disease relevance. KOREAN JOURNAL OF PEDIATRICS 2015; 58:239-44. [PMID: 26300937 PMCID: PMC4543182 DOI: 10.3345/kjp.2015.58.7.239] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 05/27/2015] [Indexed: 01/21/2023]
Abstract
The complement system is part of the innate immune response and as such defends against invading pathogens, removes immune complexes and damaged self-cells, aids organ regeneration, confers neuroprotection, and engages with the adaptive immune response via T and B cells. Complement activation can either benefit or harm the host organism; thus, the complement system must maintain a balance between activation on foreign or modified self surfaces and inhibition on intact host cells. Complement regulators are essential for maintaining this balance and are classified as soluble regulators, such as factor H, and membrane-bound regulators. Defective complement regulators can damage the host cell and result in the accumulation of immunological debris. Moreover, defective regulators are associated with several autoimmune diseases such as atypical hemolytic uremic syndrome, dense deposit disease, age-related macular degeneration, and systemic lupus erythematosus. Therefore, understanding the molecular mechanisms by which the complement system is regulated is important for the development of novel therapies for complement-associated diseases.
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Affiliation(s)
- Heeyeon Cho
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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10
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Lee JM, Park YS, Lee JH, Park SJ, Shin JI, Park YH, Yoo KH, Cho MH, Kim SY, Kim SH, Namgoong MK, Lee SJ, Lee JH, Cho HY, Han KH, Kang HG, Ha IS, Bae JS, Kim NKD, Park WY, Cheong HI. Atypical hemolytic uremic syndrome: Korean pediatric series. Pediatr Int 2015; 57:431-8. [PMID: 25443527 DOI: 10.1111/ped.12549] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 11/19/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND Atypical hemolytic uremic syndrome (aHUS) is a rare disease with a genetic predisposition. Few studies have evaluated the disease in the Asian population. We studied a Korean pediatric cohort to delineate the clinical characteristics and genotypes. METHODS A multicenter cohort of 51 Korean children with aHUS was screened for mutations using targeted exome sequencing covering 46 complement related genes. Anti-complement-factor-H autoantibody (anti-CFH) titers were measured. Multiplex ligation-dependent probe amplification assay was performed to detect deletions in the complement factor-H related protein genes (CFHR) in the patients as well as in 100 healthy Korean controls. We grouped the patients according to etiology and compared the clinical features using Mann-Whitney U-test and chi-squared test. RESULTS Fifteen patients (group A, 29.7%) had anti-CFH, and mutations were detected in 11 (group B, 21.6%), including one with combined mutations. The remaining 25 (group C, 49.0%) were negative for both. The prevalence of anti-CFH was higher than the worldwide level. Group A had a higher onset age than group B, although the difference was not significant. Group B had the worst renal outcome. Gene frequencies of homozygous CFHR1 deletion were 73.3%, 2.7% and 1% in group A, group B + C and the control, respectively. CONCLUSIONS The incidence of anti-CFH in the present Korean aHUS cohort was high. Clinical outcomes largely conformed to the previous reports. Although the sample size was limited, this cohort provides a reassessment of clinicogenetic features of aHUS in Korean children.
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Affiliation(s)
- Jiwon M Lee
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea
| | - Young Seo Park
- Department of Pediatrics, Asan Medical Center, University of Ulsan, Seoul, Korea
| | - Joo Hoon Lee
- Department of Pediatrics, Asan Medical Center, University of Ulsan, Seoul, Korea
| | - Se Jin Park
- Department of Pediatrics, Ajou University School of Medicine, Suwon, Korea
| | - Jae Il Shin
- Department of Pediatrics, Severance Children's Hospital, Yonsei University, Seoul, Korea
| | - Yong-Hoon Park
- Department of Pediatrics, Yeungnam University College of Medicine, Daegu, Korea
| | - Kee Hwan Yoo
- Department of Pediatrics, Korea University Guro Hospital, Seoul, Korea
| | - Min Hyun Cho
- Department of Pediatrics, Kyungpook National University Hospital, Daegu, Korea
| | - Su-Young Kim
- Department of Pediatrics, Pusan National University Children's Hospital, Yangsan, Korea
| | - Seong Heon Kim
- Department of Pediatrics, Pusan National University Children's Hospital, Yangsan, Korea
| | - Mee Kyung Namgoong
- Department of Pediatrics, Wonju College of Medicine, Yonsei University, Wonju, Korea
| | - Seung Joo Lee
- Department of Pediatrics, Ehwa University Mokdong Hospital, Seoul, Korea
| | - Jun Ho Lee
- Department of Pediatrics, Bundang CHA Hospital, Seongnam, Korea
| | - Hee Yeon Cho
- Department of Pediatrics, Samsung Medical Center, Seoul, Korea
| | - Kyoung Hee Han
- Department of Pediatrics, Jeju University Hospital, Jeju, Korea
| | - Hee Gyung Kang
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea.,Research Coordination Center for Rare Diseases, Seoul National University Hospital, Seoul, Korea
| | - Il Soo Ha
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea
| | - Jun-Seok Bae
- Samsung Genome Institute, Samsung Medical Center, Seoul, Korea.,Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, Korea
| | - Nayoung K D Kim
- Samsung Genome Institute, Samsung Medical Center, Seoul, Korea
| | - Woong-Yang Park
- Samsung Genome Institute, Samsung Medical Center, Seoul, Korea.,Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Hae Il Cheong
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea.,Research Coordination Center for Rare Diseases, Seoul National University Hospital, Seoul, Korea.,Kidney Research Institute, Medical Research Center, Seoul National University College of Medicine, Seoul, Korea
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11
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Rafiq A, Tariq H, Abbas N, Shenoy R. Atypical hemolytic-uremic syndrome: a case report and literature review. AMERICAN JOURNAL OF CASE REPORTS 2015; 16:109-14. [PMID: 25708146 PMCID: PMC4341946 DOI: 10.12659/ajcr.892907] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Patient: Female, 59 Final Diagnosis: Atyipcal hemolytic uremic syndrome Symptoms: Delirium • headache Medication: — Clinical Procedure: — Specialty: Hematology
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Affiliation(s)
- Arsalan Rafiq
- Department of Internal Medicine, Bronx Lebanon Hospital Center, Bronx, NY, USA
| | - Hassan Tariq
- Department of Internal Medicine, Bronx Lebanon Hospital Center, Bronx, NY, USA
| | - Naeem Abbas
- Department of Internal Medicine, Bronx Lebanon Hospital Center, Bronx, NY, USA
| | - Roopalekha Shenoy
- Department of Internal Medicine, Bronx Lebanon Hospital Center, Bronx, NY, USA
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12
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Abstract
Hemolytic uremic syndrome (HUS) is defined by the triad of mechanical hemolytic anemia, thrombocytopenia and renal impairment. Atypical HUS (aHUS) defines non Shiga-toxin-HUS and even if some authors include secondary aHUS due to Streptococcus pneumoniae or other causes, aHUS designates a primary disease due to a disorder in complement alternative pathway regulation. Atypical HUS represents 5 -10% of HUS in children, but the majority of HUS in adults. The incidence of complement-aHUS is not known precisely. However, more than 1000 aHUS patients investigated for complement abnormalities have been reported. Onset is from the neonatal period to the adult age. Most patients present with hemolytic anemia, thrombocytopenia and renal failure and 20% have extra renal manifestations. Two to 10% die and one third progress to end-stage renal failure at first episode. Half of patients have relapses. Mutations in the genes encoding complement regulatory proteins factor H, membrane cofactor protein (MCP), factor I or thrombomodulin have been demonstrated in 20-30%, 5-15%, 4-10% and 3-5% of patients respectively, and mutations in the genes of C3 convertase proteins, C3 and factor B, in 2-10% and 1-4%. In addition, 6-10% of patients have anti-factor H antibodies. Diagnosis of aHUS relies on 1) No associated disease 2) No criteria for Shigatoxin-HUS (stool culture and PCR for Shiga-toxins; serology for anti-lipopolysaccharides antibodies) 3) No criteria for thrombotic thrombocytopenic purpura (serum ADAMTS 13 activity > 10%). Investigation of the complement system is required (C3, C4, factor H and factor I plasma concentration, MCP expression on leukocytes and anti-factor H antibodies; genetic screening to identify risk factors). The disease is familial in approximately 20% of pedigrees, with an autosomal recessive or dominant mode of transmission. As penetrance of the disease is 50%, genetic counseling is difficult. Plasmatherapy has been first line treatment until presently, without unquestionable demonstration of efficiency. There is a high risk of post-transplant recurrence, except in MCP-HUS. Case reports and two phase II trials show an impressive efficacy of the complement C5 blocker eculizumab, suggesting it will be the next standard of care. Except for patients treated by intensive plasmatherapy or eculizumab, the worst prognosis is in factor H-HUS, as mortality can reach 20% and 50% of survivors do not recover renal function. Half of factor I-HUS progress to end-stage renal failure. Conversely, most patients with MCP-HUS have preserved renal function. Anti-factor H antibodies-HUS has favourable outcome if treated early.
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Affiliation(s)
- Chantal Loirat
- Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Université Paris VII, Pediatric Nephrology Department, Paris, France.
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13
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Abstract
Hemolytic uremic syndrome (HUS) is defined by the triad of mechanical hemolytic anemia, thrombocytopenia and renal impairment. Atypical HUS (aHUS) defines non Shiga-toxin-HUS and even if some authors include secondary aHUS due to Streptococcus pneumoniae or other causes, aHUS designates a primary disease due to a disorder in complement alternative pathway regulation. Atypical HUS represents 5 -10% of HUS in children, but the majority of HUS in adults. The incidence of complement-aHUS is not known precisely. However, more than 1000 aHUS patients investigated for complement abnormalities have been reported. Onset is from the neonatal period to the adult age. Most patients present with hemolytic anemia, thrombocytopenia and renal failure and 20% have extra renal manifestations. Two to 10% die and one third progress to end-stage renal failure at first episode. Half of patients have relapses. Mutations in the genes encoding complement regulatory proteins factor H, membrane cofactor protein (MCP), factor I or thrombomodulin have been demonstrated in 20-30%, 5-15%, 4-10% and 3-5% of patients respectively, and mutations in the genes of C3 convertase proteins, C3 and factor B, in 2-10% and 1-4%. In addition, 6-10% of patients have anti-factor H antibodies. Diagnosis of aHUS relies on 1) No associated disease 2) No criteria for Shigatoxin-HUS (stool culture and PCR for Shiga-toxins; serology for anti-lipopolysaccharides antibodies) 3) No criteria for thrombotic thrombocytopenic purpura (serum ADAMTS 13 activity > 10%). Investigation of the complement system is required (C3, C4, factor H and factor I plasma concentration, MCP expression on leukocytes and anti-factor H antibodies; genetic screening to identify risk factors). The disease is familial in approximately 20% of pedigrees, with an autosomal recessive or dominant mode of transmission. As penetrance of the disease is 50%, genetic counseling is difficult. Plasmatherapy has been first line treatment until presently, without unquestionable demonstration of efficiency. There is a high risk of post-transplant recurrence, except in MCP-HUS. Case reports and two phase II trials show an impressive efficacy of the complement C5 blocker eculizumab, suggesting it will be the next standard of care. Except for patients treated by intensive plasmatherapy or eculizumab, the worst prognosis is in factor H-HUS, as mortality can reach 20% and 50% of survivors do not recover renal function. Half of factor I-HUS progress to end-stage renal failure. Conversely, most patients with MCP-HUS have preserved renal function. Anti-factor H antibodies-HUS has favourable outcome if treated early.
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14
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Jung S, Kang ES, Ki CS, Kim DW, Paik KH, Chang YS. Successful therapeutic plasma exchange in a 3.2-kg body weight neonate with atypical hemolytic uremic syndrome. J Clin Apher 2011; 26:162-5. [DOI: 10.1002/jca.20283] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Accepted: 12/25/2010] [Indexed: 12/22/2022]
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15
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Waters AM, Licht C. aHUS caused by complement dysregulation: new therapies on the horizon. Pediatr Nephrol 2011; 26:41-57. [PMID: 20556434 PMCID: PMC2991208 DOI: 10.1007/s00467-010-1556-4] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Revised: 04/23/2010] [Accepted: 04/26/2010] [Indexed: 12/19/2022]
Abstract
Atypical hemolytic uremic syndrome (aHUS) is a heterogeneous disease that is caused by defective complement regulation in over 50% of cases. Mutations have been identified in genes encoding both complement regulators [complement factor H (CFH), complement factor I (CFI), complement factor H-related proteins (CFHR), and membrane cofactor protein (MCP)], as well as complement activators [complement factor B (CFB) and C3]. More recently, mutations have also been identified in thrombomodulin (THBD), an anticoagulant glycoprotein that plays a role in the inactivation of C3a and C5a. Inhibitory autoantibodies to CFH account for an additional 5-10% of cases and can occur in isolation or in association with mutations in CFH, CFI, CFHR 1, 3, 4, and MCP. Plasma therapies are considered the mainstay of therapy in aHUS secondary to defective complement regulation and may be administered as plasma infusions or plasma exchange. However, in certain cases, despite initiation of plasma therapy, renal function continues to deteriorate with progression to end-stage renal disease and renal transplantation. Recently, eculizumab, a humanized monoclonal antibody against C5, has been described as an effective therapeutic strategy in the management of refractory aHUS that has failed to respond to plasma therapy. Clinical trials are now underway to further evaluate the efficacy of eculizumab in the management of both plasma-sensitive and plasma-resistant aHUS.
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Affiliation(s)
- Aoife M. Waters
- Department of Nephrology, Great Ormond Street Hospital, London, WC1N 3JH UK ,University College London, Institute of Child Health, London, UK
| | - Christoph Licht
- Division of Nephrology, Hospital for Sick Children, Toronto, ON Canada ,Department of Paediatrics, University of Toronto, Toronto, ON Canada
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16
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Noris M, Remuzzi G. Genetics and Genetic Testing in Hemolytic Uremic Syndrome/Thrombotic Thrombocytopenic Purpura. Semin Nephrol 2010; 30:395-408. [DOI: 10.1016/j.semnephrol.2010.06.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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17
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Fakhouri F, de Jorge EG, Brune F, Azam P, Cook HT, Pickering MC. Treatment with human complement factor H rapidly reverses renal complement deposition in factor H-deficient mice. Kidney Int 2010; 78:279-86. [PMID: 20445496 DOI: 10.1038/ki.2010.132] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Total deficiency of complement factor H (CFH) is associated with dense deposit disease and atypical hemolytic uremic syndrome. CFH is the major regulator of the alternative pathway of complement activation and its complete deficiency results in uncontrolled C3 activation through this pathway and secondary C3 deficiency. Plasma infusion, as a source of CFH, has been used with variable success to treat renal disease associated with its deficiency. However, the risks of volume and protein overload limit this therapeutic approach. In this study, we investigated the efficacy of a purified human CFH (hCFH) preparation in Cfh-gene knockout mice. These mice spontaneously develop both secondary plasma C3 deficiency and a renal abnormality characterized by massive accumulation of C3 along the glomerular basement membrane. The renal lesion is analogous to human dense deposit disease. Treatment of knockout mice with hCFH resulted in rapid normalization of plasma C3 levels and resolution of the glomerular basement membrane C3 deposition. Long-term treatment of mice with hCFH was not possible because of the development of an immune response against hCFH. Hence, we suggest that hCFH can be an effective alternative therapy to plasma infusions in patients with renal disease associated with CFH deficiency.
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18
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Severe atypical HUS caused by CFH S1191L--case presentation and review of treatment options. Pediatr Nephrol 2010; 25:97-104. [PMID: 19856002 DOI: 10.1007/s00467-009-1306-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 08/10/2009] [Accepted: 08/11/2009] [Indexed: 02/04/2023]
Abstract
Atypical hemolytic uremic syndrome (aHUS) has been associated with defective regulation of the alternative complement pathway. Although the use of plasma therapy is recommended, there is little consensus on the optimal treatment regimen. The outcome in many cases remains poor despite an improvement in our understanding of the pathology of aHUS. We have followed a female patient with aHUS associated with heterozygous complement Factor H (CFH) mutation (S1191L) over a period of 15 years. She has been plasma dependent since infancy and has subsequently progressed to end stage kidney disease (ESKD) requiring dialysis treatment. Despite ESKD she still depends on regular plasma infusions to prevent thrombocytopenia. The long-term treatment plan for this patient is challenging. Renal transplantation in patients with the S1191L mutation of the CFH gene carries a high risk of failure due to recurrence of aHUS in the renal graft. Thus, the only available curative treatment seems to be combined liver-kidney transplantation, covered by intensive plasma therapy, which comes with a high risk of morbidity and mortality. Antibodies against key activating components of the complement cascade may provide a promising alternative therapeutic strategy in the future. Eculizumab, a monoclonal humanized anti-C5 antibody, has recently been shown to be effective and well-tolerated in patients with paroxysmal nocturnal hemoglobinuria by preventing complement-mediated lysis of affected erythrocytes. Treatment of our patient with eculizumab is supported by recent reports on its successful use in two (pediatric and adult) patients with complement-based aHUS.
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Affiliation(s)
- Marina Noris
- Clinical Research Center for Rare Diseases Aldo e Cele Daccò, Mario Negri Institute for Pharmacological Research, Bergamo, Italy
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20
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Sethi SK, Marie-Agnes DD, Thaker N, Hari P, Bagga A. Hemolytic uremic syndrome due to homozygous factor H deficiency. Clin Exp Nephrol 2009; 13:526-530. [PMID: 19568827 DOI: 10.1007/s10157-009-0205-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2009] [Accepted: 06/01/2009] [Indexed: 10/20/2022]
Abstract
The majority of complement factor H mutations associated with atypical hemolytic uremic syndrome (HUS) are heterozygous. Homozygous mutations causing atypical hemolytic uremic syndrome are rare. We report a 7-month-old boy with HUS, severe hypocomplementemia (low C3 and normal C4 levels), and extremely low circulating levels of factor H. Genetic analysis showed homozygous 4 bp deletion in the gene encoding factor H in the patient, with his parents being carriers. The patient showed progression to end-stage renal disease and is presently on chronic ambulatory peritoneal dialysis.
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Affiliation(s)
- Sidharth Kumar Sethi
- Division of Pediatric Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
| | - Dragon-Durey Marie-Agnes
- Laboratoire d'Immunologie, Hôpital Européen Georges Pompidou, Université Paris Descartes, Paris, France
| | - Neelam Thaker
- Division of Pediatric Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
| | - Pankaj Hari
- Division of Pediatric Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
| | - Arvind Bagga
- Division of Pediatric Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India.
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Watt T, Warshaw B, Katzenstein HM. Atypical hemolytic uremic syndrome responsive to steroids and intravenous immune globulin. Pediatr Blood Cancer 2009; 53:90-1. [PMID: 19301397 DOI: 10.1002/pbc.21951] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Atypical hemolytic uremic syndrome remains a challenge to diagnose and treat, with significant acute morbidity and risk for progression to end stage renal disease. Treatment strategies center on plasma exchange but do not necessarily affect the progression of disease. We report the case of a patient with atypical HUS resulting from a mutation in the complement pathway who responded to treatment with steroids and IVIG, therefore avoiding transfusion or plasma exchange.
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Affiliation(s)
- Tanya Watt
- Aflac Cancer Center and Blood Disorders Service, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, Georgia, USA
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22
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The spectrum of phenotypes caused by variants in the CFH gene. Mol Immunol 2009; 46:1573-94. [PMID: 19297022 DOI: 10.1016/j.molimm.2009.02.013] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Revised: 02/09/2009] [Accepted: 02/11/2009] [Indexed: 12/24/2022]
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Ariceta G, Besbas N, Johnson S, Karpman D, Landau D, Licht C, Loirat C, Pecoraro C, Taylor CM, Van de Kar N, Vandewalle J, Zimmerhackl LB. Guideline for the investigation and initial therapy of diarrhea-negative hemolytic uremic syndrome. Pediatr Nephrol 2009; 24:687-96. [PMID: 18800230 DOI: 10.1007/s00467-008-0964-1] [Citation(s) in RCA: 216] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Revised: 03/13/2008] [Accepted: 03/14/2008] [Indexed: 12/13/2022]
Abstract
This guideline for the investigation and initial treatment of atypical hemolytic uremic syndrome (HUS) is intended to offer an approach based on opinion, as evidence is lacking. It builds on the current ability to identify the etiology of specific diagnostic sub-groups of HUS. HUS in children is mostly due to infection, enterohemorrhagic Escherichia coli (EHEC), Shigella dysenteriae type 1 in some geographic regions, and invasive Streptococcus pneumoniae. These sub-groups are relatively straightforward to diagnose. Their management, which is outside the remit of this guideline, is related to control of infection where that is necessary and supportive measures for the anemia and acute renal failure. A thorough investigation of the remainder of childhood HUS cases, commonly referred to as "atypical" HUS, will reveal a risk factor for the syndrome in approximately 60% of cases. Disorders of complement regulation are, numerically, the most important. The outcome for children with atypical HUS is poor, and, because of the rarity of these disorders, clinical experience is scanty. Some cases of complement dysfunction appear to respond to plasma therapy. The therapeutic part of this guideline is the consensus of the contributing authors and is based on limited information from uncontrolled studies. The guideline proposes urgent and empirical plasmapheresis replacement with whole plasma fraction for the first month after diagnosis. This should only be undertaken in specialized pediatric nephrology centers where appropriate medical and nursing skills are available. The guideline includes defined terminology and audit points so that the early clinical effectiveness of the strategy can be evaluated.
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Abstract
About 60% of non-Stx-associated aHUS are due to the defect of protection of endothelial cells from complement activation, secondary to mutations in the genes of CFH, MCP, IF, BF, or C3. In addition, 10% of patients have anti-CFH antibodies. While the risk of post-transplant recurrence is less than 1% in Stx-HUS patients, it is approximately 80% in CFH or IF-mutated patients, 20% in MCP-mutated patients, and 30% in patients with no mutation. Patients with anti-CFH antibodies probably also are at risk of recurrence. While MCP-mutated patients can reasonably go to transplantation, recent reports suggest that plasmatherapy started before surgery and maintained life-long may prevent recurrence in CFH-mutated patients. Four successful liver-kidney transplantation utilizing plasmatherapy in CFH-mutated children have been reported recently. In summary, the risk of post-transplant recurrence can now be approached according to genotype. Therefore, aHUS patients should undergo complement determination, screening for anti-CFH antibodies, and genotyping before transplantation. Kidney or kidney + liver transplantation with concomitant plasmatherapy need to be evaluated by prospective trials in patients with hereditary complement abnormalities.
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Affiliation(s)
- Chantal Loirat
- Assistance Publique, Hôpitaux de Paris, Hôpital Robert Debré, Université Paris, Faculté de Médecine Denis Diderot, Service de Néphrologie, Paris, France.
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Pickering MC, Cook HT. Translational mini-review series on complement factor H: renal diseases associated with complement factor H: novel insights from humans and animals. Clin Exp Immunol 2008; 151:210-30. [PMID: 18190458 PMCID: PMC2276951 DOI: 10.1111/j.1365-2249.2007.03574.x] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/13/2007] [Indexed: 01/28/2023] Open
Abstract
Factor H is the major regulatory protein of the alternative pathway of complement activation. Abnormalities in factor H have been associated with renal disease, namely glomerulonephritis with C3 deposition including membranoproliferative glomerulonephritis (MPGN) and the atypical haemolytic uraemic syndrome (aHUS). Furthermore, a common factor H polymorphism has been identified as a risk factor for the development of age-related macular degeneration. These associations suggest that alternative pathway dysregulation is a common feature in the pathogenesis of these conditions. However, with respect to factor H-associated renal disease, it is now clear that distinct molecular defects in the protein underlie the pathogenesis of glomerulonephritis and HUS. In this paper we review the associations between human factor H dysfunction and renal disease and explore how observations in both spontaneous and engineered animal models of factor H dysfunction have contributed to our understanding of the pathogenesis of factor H-related renal disease.
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Affiliation(s)
- M C Pickering
- Molecular Genetics and Rheumatology Section, Faculty of Medicine, Imperial College, Hammersmith Campus, London, UK.
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Davin JC, Strain L, Goodship THJ. Plasma therapy in atypical haemolytic uremic syndrome: lessons from a family with a factor H mutation. Pediatr Nephrol 2008; 23:1517-21. [PMID: 18483746 PMCID: PMC2459233 DOI: 10.1007/s00467-008-0833-y] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Revised: 02/13/2008] [Accepted: 03/06/2008] [Indexed: 11/23/2022]
Abstract
Whilst randomised control trials are undoubtedly the best way to demonstrate whether plasma exchange or infusion alone is the best first-line treatment for patients with atypical haemolytic uremic syndrome (aHUS), individual case reports can provide valuable information. To that effect, we have had the unique opportunity to follow over a 10-year period three sisters with aHUS associated with a factor H mutation (CFH). Two of the sisters are monozygotic twins. A similar natural evolution and response to treatment would be expected for the three patients, as they all presented with the same at-risk polymorphisms for CFH and CD46 and no identifiable mutation in either CD46 or CFI. Our report of different modalities of treatment of the initial episode and of three transplantations and relapses in the transplant in two of them, strongly suggest that intensive plasma exchange, both acutely and prophylactically, can maintain the long-term function of both native kidneys and allografts. In our experience, the success of plasma therapy is dependent on the use of plasma exchange as opposed to plasma infusion alone, the prolongation of daily plasma exchange after normalisation of haematological parameters followed by prophylactic plasma exchange, the use of prophylactic plasma exchange prior to transplantation and the use of prophylactic plasma exchange at least once a week posttransplant with immediate intensification of treatment if there are any signs of recurrence.
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Affiliation(s)
- Jean Claude Davin
- Pediatric Nephrology, Emma Children's Hospital/ Academic Medical Centre, 9 Meibergdreef, 1105, Amsterdam Z-O, The Netherlands.
| | - Lisa Strain
- grid.1006.70000000104627212Institute of Human Genetics, University of Newcastle Upon Tyne, Newcastle Upon Tyne, UK
| | - Tim H. J. Goodship
- grid.1006.70000000104627212Institute of Human Genetics, University of Newcastle Upon Tyne, Newcastle Upon Tyne, UK
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Loirat C, Noris M, Fremeaux-Bacchi V. Complement and the atypical hemolytic uremic syndrome in children. Pediatr Nephrol 2008; 23:1957-72. [PMID: 18594873 PMCID: PMC6904381 DOI: 10.1007/s00467-008-0872-4] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 04/22/2008] [Accepted: 04/22/2008] [Indexed: 12/20/2022]
Abstract
Over the past decade, atypical hemolytic uremic syndrome (aHUS) has been demonstrated to be a disorder of the regulation of the complement alternative pathway. Among approximately 200 children with the disease, reported in the literature, 50% had mutations of the complement regulatory proteins factor H, membrane cofactor protein (MCP) or factor I. Mutations in factor B and C3 have also been reported recently. In addition, 10% of children have factor H dysfunction due to anti-factor H antibodies. Early age at onset appears as characteristic of factor H and factor I mutated patients, while MCP-associated HUS is not observed before age 1 year. Low C3 level may occur in patients with factor H and factor I mutation, while C3 level is generally normal in MCP-mutated patients. Normal plasma factor H and factor I levels do not preclude the presence of a mutation in these genes. The worst prognosis is for factor H-mutated patients, as 60% die or reach end-stage renal disease (ESRD) within the first year after onset of the disease. Patients with mutations in MCP have a relapsing course, but no patient has ever reached ESRD in the first year of the disease. Half of the patients with factor I mutations have a rapid evolution to ESRD, but half recover. Early intensive plasmatherapy appears to have a beneficial effect, except in MCP-mutated patients. There is a high risk of graft loss for HUS recurrence or thrombosis in all groups except the MCP-mutated group. Recent success of liver-kidney transplantation combined with plasmatherapy opens this option for patients with mutations of factors synthesized in the liver. New therapies such as factor H concentrate or complement inhibitors offer hope for the future.
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Affiliation(s)
- Chantal Loirat
- Hôpitaux de Paris, Université Paris 7, Hôpital Robert Debré, Pediatric Nephrology, Paris, France.
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Noris M, Remuzzi G. Translational mini-review series on complement factor H: therapies of renal diseases associated with complement factor H abnormalities: atypical haemolytic uraemic syndrome and membranoproliferative glomerulonephritis. Clin Exp Immunol 2007; 151:199-209. [PMID: 18070148 DOI: 10.1111/j.1365-2249.2007.03558.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Genetic and acquired abnormalities in complement factor H (CFH) have been associated with two different human renal diseases: haemolytic uraemic syndrome and membrano proliferative glomerulonephritis. The new genetic and pathogenetic findings in these diseases and their clinical implications for the management and cure of patients are reviewed in this paper.
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Affiliation(s)
- M Noris
- Clinical Research Center for Rare Diseases Aldo e Cele Daccò, Mario Negri Institute for Pharmacological Research, Villa Camozzi - Ranica (BG), Italy.
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Biran V, Fau S, Jamal T, Veinberg F, Renolleau S, Gold F, Bensman A, Ulinski T. Perinatal asphyxia may present with features of neonatal atypical hemolytic uremic syndrome. Pediatr Nephrol 2007; 22:2129-32. [PMID: 17674053 DOI: 10.1007/s00467-007-0570-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2007] [Revised: 06/20/2007] [Accepted: 06/25/2007] [Indexed: 12/24/2022]
Abstract
Hemolytic uremic syndrome (HUS) is the consequence of platelet consumption at sites of endothelial injury. Perinatal asphyxia (PA) may cause renal failure after birth and can be associated with disseminated intravascular coagulopathy (DIC) with platelet consumption. No biological investigation permits us to distinguish clearly between neonatal HUS and DIC. We report on three neonates with renal failure due to different degrees of PA. They presented biological features compatible with HUS, such as fragmentocytes ( approximately 2%), thrombopenia (<50,000/mm(3)), and anemia (<8 g/dl). One patient required peritoneal dialysis. Haptoglobin was undetectable for all three patients. Factor H and factor I, as well as components of the complement system (C3 and C4) and ADAMTS13 activity, were decreased. Two patients received daily fresh frozen plasma infusions over the first 4 weeks. Renal function improved in two patients; one patient had chronic renal failure. No neurological sequelae were noted. All blood parameters suggestive of thrombotic microangiopathy (TMA) were normal on days 12, 30, and 60. We hypothesize that endothelial cell damage concomitant with PA may lead to a vicious circle that results in consumption of platelets and plasma factors involved in hemostasis and/or fibrinolysis. In conclusion, PA, DIC and HUS are difficult to distinguish, and endothelial cell damage may be their common pathophysiological pathway.
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Affiliation(s)
- Valérie Biran
- Department of Neonatology, Hôpital Trousseau, AP-HP, University of Paris VI, Paris, France
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Recurrence of haemolytic uraemic syndrome after renal transplantation. Curr Opin Organ Transplant 2007. [DOI: 10.1097/mot.0b013e3282ef3d64] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Jokiranta TS, Zipfel PF, Fremeaux-Bacchi V, Taylor CM, Goodship TJH, Noris M. Where next with atypical hemolytic uremic syndrome? Mol Immunol 2007; 44:3889-900. [PMID: 17768107 DOI: 10.1016/j.molimm.2007.06.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Indexed: 12/21/2022]
Abstract
Hemolytic uremic syndrome (HUS) is a systemic disease characterized by damage to endothelial cells, erythrocytes and kidney glomeruli. A "typical" form of HUS follows gastrointestinal infection with enterohemorrhagic E. coli (e.g. O157:H7). Atypical HUS (aHUS) is not associated with gastrointestinal infections but is sporadic or familial in nature. Approximately 50% of aHUS cases are associated with a mutation in one or more genes coding for proteins involved in regulation or activation of the alternative pathway of complement. The link between the disease and the mutations shows the important balance of the alternative pathway between activation and regulation on host cell surfaces. It also demonstrates the power of this pathway in destroying cellular targets in general. In this review we discuss the current knowledge on pathogenesis, classification, diagnostics and management of this disease. We indicate a comprehensive diagnostic approach for aHUS based on the latest knowledge on complement dysregulation to gain both immediate and future patient benefit by assisting in choosing more appropriate therapy for each patient. We also indicate directions in which therapy of aHUS might improve and indicate the need to re-think the terminology and categorisation of the HUS-like diseases so that any advantage in the understanding of complement regulatory problems can be applied to patients accurately.
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Affiliation(s)
- T Sakari Jokiranta
- Department of Bacteriology and Immunology, Haartman Institute and HUSLAB, University of Helsinki and Helsinki University Central Hospital, FIN-00290 Helsinki, Finland.
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