Exome Sequencing Identifies Glycosylation Defects As a Probable Cause of Immune Thrombotic Thrombocytopenic Purpura

Background: Immune thrombotic thrombocytopenic purpura (iTTP) is a potentially fatal syndrome, resulting primarily from autoantibodies against ADAMTS13. However, the mechanism underlying the autoantibody formation and the contribution of other genomic alterations to the pathogenesis of iTTP are largely unknown. Methods: Whole exome sequencing (WES) and bioinformatic analyses were performed to determine the genetic variations in 40 patients with iTTP who had ADAMTS13 activity <10 IU/dL and a positive inhibitor or an elevated anti-ADAMTS13 IgG in concordance with clinical presentations of severe thrombocytopenia and microangiopathic hemolytic anemia with various degrees of organ injury. WES was also performed at the same time in fifteen age-, gender-, and ethnicity- matched individuals who did not have a history of iTTP or other hematological disorders as controls. Results: WES identified variants or mutations in the genes involving in glycosylation, including O-linked glycosylation, to be the major pathway affected in patients with iTTP. We propose that the altered glycosylation may be responsible for the development of autoantibodies against ADAMTS13 which impair the proteolytic cleavage of von Willebrand factor, accelerate the clearance of ADAMTS13 from circulation, and result in severe thrombocytopenia platelets in patients with iTTP. We also identified defects in ankyrin repeat containing protein ANKRD36C, a protein with hitherto unknown function, as the most statistically significant genomic alterations associated with iTTP (p < 10-5). Moreover, candidate gene analysis revealed that various genes involving in hemostasis, complement activation, platelet function and signaling pathway, and inflammation were all affected in patients with iTTP, which may contribute to the onset, progress, severity, and long-term outcome of iTTP. Finally, we also identified two patient subgroups where the disease mechanism might be different. Conclusion: Our findings provide novel insight into the pathogenic mechanism underlying ADAMTS13 autoantibody production and the potential contribution of other genetic abnormalities in modifying the iTTP clinical presentations in the individuals with severe deficiency of plasma ADAMTS13 activity. Disclosures Zheng: Alexion: Speakers Bureau; Ablynx/Sanofi: Consultancy, Speakers Bureau; Shire/Takeda: Research Funding; Clotsolution: Other: Co-Founder.

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Exome Sequencing Identifies Glycosylation Defects as a Probable Cause of Immune-Mediated Thrombotic Thrombocytopenic Purpura

American Journal of Clinical Pathology ◽

10.1093/ajcp/aqz112.037 ◽

2019 ◽

Vol 152 (Supplement_1) ◽

pp. S19-S20

Author(s):

Malay Kumar Basu ◽

Elizabeth Staley ◽

Konstantine Halkidis ◽

Jingrui (Jean) Sui ◽

Nicole K Kocher ◽

...

Keyword(s):

Exome Sequencing ◽

Thrombotic Thrombocytopenic Purpura ◽

Potential Contribution ◽

Healthy Controls ◽

Adamts13 Activity ◽

Autoantibody Production ◽

Thrombocytopenic Purpura ◽

Long Term Outcome ◽

Immune Mediated ◽

Severe Deficiency

Abstract Background Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a potentially fatal syndrome, resulting from autoantibodies against ADAMTS13. However, the mechanism underlying autoantibody formation is not known. Neither is known about the other genetic abnormality in the setting of severe deficiency of plasma ADAMTS13 activity. Methods Whole-exome sequencing (WES) was performed in 40 patients with iTTP who had plasma ADAMTS13 activity <10% and a positive inhibitor or elevated anti-ADAMTS13 IgG. Fifteen age- and ethnicity-matched subjects who never had iTTP were recruited as healthy controls. Results WES identified mutations in the genes involved in glycosylation, including O-linked glycosylation to be the major pathway affected in patients with iTTP. Mass spectrometry confirmed the changes in plasma levels of various glycoproteins in patients with acute iTTP when compared with those in the healthy controls. The altered glycosylation in glycoproteins may be responsible for the development of autoantibodies, susceptibility of von Willebrand factor to proteolysis by ADAMTS13, and the clearance of platelets in iTTP patients. Moreover, candidate gene analysis revealed that various genes involving in hemostasis, complement activation, platelet number and function, and inflammation were all affected in patients with iTTP, which may contribute to the onset, progress, severity, and long-term outcome of iTTP. Conclusions Our findings provide novel insight into a pathogenic mechanism underlying autoantibody production and the potential contribution of other genetic abnormalities in pathogenesis of iTTP in the individuals with severe deficiency of plasma ADAMTS13 activity. Future Direction Further studies are warranted to determine the specific glycosylation patterns of various plasma and cellular proteins in patients with iTTP and to determine the synergistic role of various gene mutations and severe ADAMTS13 deficiency in the pathogenesis of iTTP.

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Retrospective Analysis of Patients Afflicted with Thrombotic Thrombocytopenic Purpura: A Single Institutional Experience.

Blood ◽

10.1182/blood.v120.21.2200.2200 ◽

2012 ◽

Vol 120 (21) ◽

pp. 2200-2200

Author(s):

Manali K. Kamdar ◽

Phillip Chae ◽

Maria Javaid ◽

Negin Mesaghian ◽

Kevin O'Brien ◽

...

Keyword(s):

Retrospective Analysis ◽

Thrombotic Thrombocytopenic Purpura ◽

Blood Group ◽

Conflicts Of Interest ◽

Severe Thrombocytopenia ◽

Adamts13 Activity ◽

Thrombocytopenic Purpura ◽

Congenital Deficiency ◽

Predominant Symptom ◽

Threatening Condition

Abstract Abstract 2200 Introduction: Thrombotic Thrombocytopenic Purpura (TTP) is an acute life threatening condition characterized by thrombocytopenia, microangiopathic hemolytic anemia, with or without renal failure or neurologic abnormalities, and without another cause for thrombotic microangiopathy. The majority of cases of TTP are associated with a low ADAMTS13 activity which results from antibody to this enzyme. A minority of patients have TTP secondary to congenital deficiency of this enzyme. The mainstay of therapy for TTP is plasmapheresis (PEX) which has increased survival in affected patients from 10% to more than 75%. While TTP is considered as an uncommon disorder, at our institution we suspected that the diagnosis was made more commonly. Therefore we set out to perform a retrospective analysis of cases of TTP to evaluate cases diagnosed over the past 10 years. Methods: We performed a retrospective analysis of all cases of microangiopathy undergoing pheresis at our institution for presumed TTP from May 2007 to April 2012. A total of 112 patients had PEX initiated for presumed TTP however 11 of these were later determined to have some other etiology causing the constellation of symptoms and PEX was discontinued. The remaining 101 patients were entered into a database and further analyzed. Demographically, we captured patients from 30 of the 100 North Carolina counties because 3 other institutions in our state perform plasma exchange for TTP. ADAMTS13 activity and inhibitor levels were measured in 69 out of 101 patients. In our registry there were 80 patients with Idiopathic TTP and 21 patients with secondary TTP. Patients with idiopathic TTP were further divided based on the ADAMTS13 activity. Results: Discussion: Our analysis demonstrated that TTP was more common in females, African American population with a median age group in the mid forties with neurological symptoms being the predominant symptom of presentation. While hematocrit was higher in patients with idiopathic TTP these patients were noted to have increased incidence of ADAMTS13 levels less than 10% with inhibitors as compared to those with secondary TTP. Idiopathic TTP patients had more incidence of multiple relapses and required more Rituximab in addition to PEX. We compared our results with the results published from the Oklahoma registry. Similar to the Oklahoma registry results patients with ADAMTS13 levels less than 10% had more severe thrombocytopenia, renal dysfunction, required more sessions of PEX, had higher relapses and percentage of death compared to patients with idiopathic TTP with ADAMTS13 levels more than 10%. Patients with ADAMTS13 less than 10% required more Rituximab during first diagnosis of idiopathic TTP. In this group blood group A+ was seen more often whereas blood group O+ was prevalent in the group with ADAMTS more than 10%. Comparison amidst these groups brought out similarities between two distinct registries in the US. Our registry is another large registry of patients similar to the Oklahoma TTP registry. While many similarities are seen with the Oklahoma group there were a few differences as cited above. Disclosures: No relevant conflicts of interest to declare.

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Factors Associated with Mortality in Patients Experiencing First Episodes of Acquired Thrombotic Thrombocytopenic Purpura (aTTP). Results of the Spanish TTP Registry

Blood ◽

10.1182/blood-2019-122665 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1082-1082

Author(s):

Julio del Rio-Garma ◽

Sabela Bobillo ◽

Javier De La Rubia ◽

Maria Cristina Pascual Izquierdo ◽

Faustino García-Candel ◽

...

Keyword(s):

Thrombotic Thrombocytopenic Purpura ◽

Laboratory Data ◽

Complete Information ◽

Biological Factor ◽

First Episode ◽

Severe Thrombocytopenia ◽

Adamts13 Activity ◽

International Consensus ◽

Thrombocytopenic Purpura ◽

The Impact

Introduction: Acquired thrombotic thrombocytopenic purpura (aTTP) is a rare, but life-threatening, hematological disorder characterized by severe thrombocytopenia, hemolytic microangiopathic anemia, and frequent organ damage. The underlying pathophysiology of aTTP is a functional deficiency of plasma ADAMTS13 activity caused by antibodies directed against the ADAMTS13 protease. Despite plasma exchange (PEX) and immunosuppression with corticosteroids, and, more recently, rituximab, which achieve remission in most patients with aTTP, 10-20% of patients are refractory to treatment and die as a result of disease progression. Most of such deaths occur during first episodes of aTTP, as subsequent relapses tend to be milder. These patients would probably benefit from new therapies aimed at temporarily halting the microvascular thrombosis. This study was aimed at identifying predictive factors of mortality during a first episode of aTTP. Methods: We searched the Spanish TTP Registry (REPTT, Registro Español de la Purpura Trombocitopénica Trombótica) for patients with a clinical diagnosis of TTP (n = 345) with ADAMTS13 activity <10%, and anti-ADAMTS13 inhibitors in plasma (n = 143). Among these, we selected 103 patients with complete information on their first episode of aTTP. The patients were diagnosed between 2004 and 2018, and all were treated with daily PEX and corticosteroids. Additional treatments (rituximab, vincristine, etc.) were used at the discretion of the attending hematologist. Clinical and laboratory data of the episodes were analyzed at diagnosis and during the course of the treatment. The impact of refractoriness, exacerbations (as defined by the international consensus; DOI: 10.1111/jth.13571) and platelet transfusions on mortality was also studied. Results: The 103 patients examined suffered a total of 111 episodes of aTTP (103 with a first episode and 8 with a relapse). Eight deaths (7.7%) took place during an initial episode of aTTP and none during relapses. The time elapsed from the diagnosis to the events of death ranged from a few hours to 36 days (Figure). One patient died before starting the treatment. In the multivariate analysis, stupor or coma at diagnosis was the only clinical and biological factor associated with mortality, as 6 out of 18 patients with stupor or coma died vs. 2 out of 85 without these symptoms (OR: 21.95% CI: 4-114; p = 0.001). Persistently low platelet counts during PEX (i.e. refractoriness) were also strong predictors of subsequent mortality, with a platelet count <20 x109/L after 6 PEX procedures yielding the highest positive and negative values (Table). Exacerbation of aTTP while on treatment occurred in 44 of the 95 patients, all of whom eventually achieved remission with no events of death. Patients with exacerbations required a higher number of PEX procedures to achieve clinical remission (23, IQR: 19-31 vs. 12, IQR: 8-16; p <0.001) and were more likely to receive rituximab (39% vs. 9%; p = 0.001). Platelets were transfused into 16 patients, including 2 patients who died a few days later and 14 survivors. Conclusions: Stupor or coma at diagnosis and lack of response to PEX by the 6th-7th day in patients experiencing first episodes of aTTP are strong predictors of mortality. These patients are candidates for new treatments aimed at controlling the microvascular thrombotic phenomena until effective immunosuppression is achieved. Disease exacerbation does not seem to increase mortality but requires a more intensive treatment. Disclosures De La Rubia: Celgene Corporation: Consultancy; AbbVie: Consultancy; AMGEN: Consultancy; Janssen: Consultancy; Takeda: Consultancy. Pascual Izquierdo:Novartis: Consultancy; Sanofi: Consultancy.

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Complement Activation May Trigger the Onset of Thrombotic Thrombocytopenic Purpura in Patients with Severe ADAMTS13 Deficiency

Blood ◽

10.1182/blood.v124.21.600.600 ◽

2014 ◽

Vol 124 (21) ◽

pp. 600-600 ◽

Cited By ~ 2

Author(s):

Xiao-Hui Hu ◽

Jialing Bao ◽

Yoshiyasu Ueda ◽

Takashi Miwa ◽

Wenchao Song ◽

...

Keyword(s):

Thrombotic Thrombocytopenic Purpura ◽

Complement Activation ◽

Factor H ◽

Severe Thrombocytopenia ◽

Complement Factor ◽

Healthy Controls ◽

Adamts13 Activity ◽

Activation Markers ◽

Thrombocytopenic Purpura ◽

Adamts13 Deficiency

Abstract Thrombotic thrombocytopenic purpura (TTP), a potential fatal syndrome, is often associated with severe deficiency of plasma ADAMTS13 activity, either resulting from ADAMTS13 mutations or acquired anti-ADAMTS13 autoantibodies that inhibit plasma ADAMTS13 activity. Patients with severe ADAMTS13 do not always have TTP signs and symptoms, which often occur following infections or inflammatory responses. The mechanism of TTP flare is not fully understood. In the present study, complement activation markers (iC3b, C5b, Bb, and C4b) were determined by enzyme-linked absorbent assays (ELISA) in the initial plasmas (prior to plasma exchange) of 20 patients with acquired TTP with severe ADAMTS13 deficiency (less than 20% of normal) and plasmas from 20 healthy controls. Of 20 TTP patients, 19 exhibited positive inhibitor in the 50:50 mixing study. Plasma levels of iC3b (1,000 ± 1,062 ng/ml), sC5b-9 (1,342±867 ng/ml), and Bb (38.2±47.7 ng/ml), as well as C4b (74.3±49.5 ng/ml) in acquired TTP patients were significantly higher than those in healthy controls (p value less than 0.01) These results indicate that complement activation in both classic and alternative pathways is a common phenomenon in patients with acquired autoimmune TTP. To demonstrate the causative effect of complement activation in TTP, we turned to our Adamts13 null mice. C57BL/6 (Adamts13-/-) mice are resistant to the development of spontaneous and Shigatoxin-induced TTP syndrome. When injected with a murine specific monoclonal antibody against complement factor H (CFH) (800 micro grams/mouse), which inhibits binding of circulating CFH to endothelial cells and C3b, Adamts13-/- mice (C57BL/6) developed more severe thrombocytopenia and anemia than wild type mice did within 6 days without additional challenge. However, renal insufficiency manifested by the increase of plasma BUN concentration was similar in both groups (Fig. 1). These results indicate that complement activation through an alternative pathway, following antibody-mediated inhibition of CFH or other complement regulatory components, may trigger the onset of TTP in light of severe ADAMTS13 deficiency. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

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Clinical and Outcomes Findings for Thrombotic Thrombocytopenic Purpura among 467 Persons with Severely Versus Not Severely Deficient ADAMTS-13 Levels.

Blood ◽

10.1182/blood.v110.11.2088.2088 ◽

2007 ◽

Vol 110 (11) ◽

pp. 2088-2088 ◽

Cited By ~ 3

Author(s):

Charles L. Bennett ◽

Thanh Ha Luu ◽

Anaadriana Zakarija ◽

Hau C. Kwaan ◽

Nicholas Bandarenko ◽

...

Keyword(s):

Thrombotic Thrombocytopenic Purpura ◽

Neutralizing Antibodies ◽

Clinical Laboratory ◽

Survival Rates ◽

Outcome Data ◽

Severe Thrombocytopenia ◽

Activity Levels ◽

Adamts13 Activity ◽

Thrombocytopenic Purpura ◽

Adamts13 Deficiency

Abstract Background: Thrombotic thrombocytopenic purpura (TTP) is a rare disorder that presents with microangiopathic hemolytic anemia and thrombocytopenia, fevers, renal insufficiency and neurologic features. We reviewed clinical, laboratory, and outcome data for TTP cases with severely deficient versus non-severely deficient ADAMTS13 activity levels. Methods: Mean and median data were from the Surveillance, Epidemiology and Risk Factors for TTP (SERF-TTP) study group for idiopathic TTP cases, the Canadian Apheresis Group (CAG), and five published series (Zheng 2004, Raife 2004, Vesely 2003 (Oklahoma TTP-HUS Registry), Matsumoto 2004 (Japan Referral Center), Bennett 2007). Results: Compared to TTP cases with near-normal ADAMTS13 activity levels (n= 282), TTP cases with severe ADAMTS13-deficiency (n=185) were more likely to have severe thrombocytopenia, normal renal function and neutralizing ADAMTS13 antibodies. Severe ADAMTS13 deficient TTP cases have better overall survival after therapeutic plasma exchange (TPE) but are more likely to relapse. TTP patients with severe ADAMTS13 deficiency were primarily categorized as idiopathic or ticlopidine-associated, while TTP patients with non-severely deficient ADAMTS13 activity levels were frequently categorized as idiopathic, secondary to drugs (clopidogrel, quinine), stem cell transplantation, or cancer. Conclusions: Severe ADAMTS13 deficiency is most commonly idiopathic, has better survival following TPE, and a 35–40% spontaneous relapse rate. By contrast, non-ADAMTS13 deficient TTP cases are usually associated with an underlying disorder or external insults. Amongst this cohort, four series have 47–62% survival rates and three series, which contain mostly idiopathic cases, have 83–90% survival rates following TPE. From this, we propose that TTP may occur by three possible mechanism; ADAMTS13-deficient (antibody-mediated), an immunologic mediated pathway independent of ADAMTS13 (i.e. quinine) that is responsive to TPE, and endothelial injury related TTP that is unresponsive to TPE. Platelet count mean (x10^9/L) Creatinine mean (mg/dl) ADAMTS13 neutralizing antibodies (%) Survival % Relapse % * <15% ADAMTS13 activity cutoff Severe ADAMTS13 Deficiency (<10–15%) SERF-TTP (n=30) 19 1.3 83 97 41 Zheng (n=16) 19 1.6 44 81 38 Bennett (n=26) 15 85 Oklahoma (n=18) 12 1.8 94 81 38 Raife (n=50) * 13 1.2 92 35 Japan (n=34) 35 91 Canada (n=11) 16 2.4 82 Not Severely Deficient ADAMTS13 Activity (> 15%) SERF-TTP (n=22) 57 3.9 35 90 0 Raife (n=57) * 44 2.7 83 9 Canada (n=17) 57 4.1 88 Zheng (n=13) 40 3.0 0 54 Bennett (n=13) 62 Japan (n=66) 9 62 Oklahoma (n=94 ) 23 47 3

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The remarkable diversity of thrombotic thrombocytopenic purpura: a perspective

Blood Advances ◽

10.1182/bloodadvances.2018018432 ◽

2018 ◽

Vol 2 (12) ◽

pp. 1510-1516 ◽

Cited By ~ 8

Author(s):

James N. George

Keyword(s):

Thrombotic Thrombocytopenic Purpura ◽

Immunosuppressive Treatment ◽

Severe Thrombocytopenia ◽

Adamts13 Activity ◽

Long Term Outcomes ◽

Thrombocytopenic Purpura ◽

Adamts13 Deficiency ◽

Few Data ◽

Autoimmune Etiology

Abstract Understanding the autoimmune etiology of acquired thrombotic thrombocytopenic purpura (TTP) has provided precision for the diagnosis and a rationale for immunosuppressive treatment. These advances have also allowed recognition of the remarkable clinical diversities of patients’ initial presentations and their long-term outcomes. These diversities are illustrated by the stories of patients from the Oklahoma TTP Registry. The initial presentation of TTP may be the discovery of unexpected severe thrombocytopenia in a patient with minimal or no symptoms. The patient may remain asymptomatic throughout treatment or may die suddenly before treatment can be started. ADAMTS13 activity may be reported as normal in a patient with characteristic clinical features of TTP, or the unexpected report of ADAMTS13 deficiency in a patient with another established disorder may lead to the discovery of TTP. ADAMTS13 activity during clinical remission is unpredictable. ADAMTS13 activity may recover and remain normal, it may remain severely deficient for many years, or it may become normal only many years after recovery. Our treatment of initial episodes and management of patients after recovery and during remission continue to change. The addition of rituximab to the treatment of acute episodes and preemptive rituximab for patients with severe ADAMTS13 deficiency during remission are reported to prevent relapse. Because TTP is uncommon, there are few data to guide these changes. Therefore our patients’ stories are profoundly influential. Their stories are the foundation of our experience, and our experience is the guide for our decisions.

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Monitoring of ADAMTS13 in Patients with Thrombotic Thrombocytopenic Purpura: Prediction of Response to Therapy, Risk of Relapse, and Long- Term Outcome.

Blood ◽

10.1182/blood.v112.11.2291.2291 ◽

2008 ◽

Vol 112 (11) ◽

pp. 2291-2291 ◽

Cited By ~ 2

Author(s):

Paul Knoebl ◽

Silvia Koder ◽

Peter Schellongowski ◽

Peter Distelmaier ◽

Peter Quehenberger ◽

...

Keyword(s):

Plasma Exchange ◽

Thrombotic Thrombocytopenic Purpura ◽

Clinical Signs ◽

Response To Therapy ◽

First Episode ◽

Adamts13 Activity ◽

Term Outcome ◽

Thrombocytopenic Purpura ◽

Long Term Outcome ◽

Risk Of Relapse

Abstract A severely reduced ADAMTS13 activity due to inhibitory autoantibodies is a key feature of acquired thrombotic thrombocytopenic purpura (TTP), leading to the persistence of ultralarge VWF multimers, platelet aggregation and disturbance of microcirculation. We followed 39 patients (8 male, 31 female, mean age 38 years) with clinical signs of TTP over a period between 5 days to 16 years and observed a total of 53 episodes of TTP. ADAMTS13 was measured with a collagen-binding assay and the FRETS-VWF73 based Technozym ADAMTS-13 assay (activity and antigen, respectively). ADAMTS13 inhibitor was measured with a modified Bethesda method with both the above mentioned assays, and with the Technozym ADAMTS-13 INH ELISA. Thirty-one patients had autoimmune TTP, and 47 episodes of TTP were analyzed in these patients. In all acute episodes, ADAMTS13 activity was below the detection limit (<0.05 U/ml), but ADAMTS13:Ag levels were below 0.1 U/ml only in 55% of the episodes. Anti-ADAMTS13 antibodies were detected in all episodes. Treatment consisted of plasma exchange (89% of the episodes), immunoadsorption (6%), steroids (70%), rituximab (15%), splenectomy (11%), aspirin (74%). Median time to platelet count normalization was 20 days (range 4–91 days), not related to the ADAMTS13-inhibitor titer. Platelet counts, LDH levels, and reticulocyte counts were better predictors of treatment response. Plasma exchange did not directly influence ADAMTS13 levels or clear the inhibitors. Three patients died during the first episode (myocardial infarction), one in 2nd relapse. ADAMTS13 activity increased >0.2 U/ml in 66% of the episodes (after median 160 days). In the remaining cases anti-ADAMTS13 antibodies persisted during remissions for up to 2 years. In 3 cases the antibody reoccurred after initial normalization of ADAMTS13 activity, and clinical relapses followed. In total, 21 relapses were observed after a median of 46 months (range 1– 87), all associated with low ADAMTS13 levels. Rituximab was given in 7 cases of relapsing TTP and resulted in complete, durable clearance of the antibodies in 100%. Determination of ADAMTS13-related parameters is useful to distinguish between autoimmune, hereditary, and secondary forms of TTP and to choose an appropriate therapy. It is also useful to predict the risk of relapse in patients with TTP in remission.

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Thrombotic Thrombocytopenic Purpura: Pathophysiology, Diagnosis, and Management

Journal of Clinical Medicine ◽

10.3390/jcm10030536 ◽

2021 ◽

Vol 10 (3) ◽

pp. 536

Author(s):

Senthil Sukumar ◽

Bernhard Lämmle ◽

Spero R. Cataland

Keyword(s):

Thrombotic Thrombocytopenic Purpura ◽

Initial Therapy ◽

Fresh Frozen Plasma ◽

Organ Injury ◽

Severe Thrombocytopenia ◽

Front Line ◽

Thrombocytopenic Purpura ◽

Fresh Frozen ◽

Biallelic Mutations ◽

Line Setting

Thrombotic thrombocytopenic purpura (TTP) is a rare thrombotic microangiopathy characterized by microangiopathic hemolytic anemia, severe thrombocytopenia, and ischemic end organ injury due to microvascular platelet-rich thrombi. TTP results from a severe deficiency of the specific von Willebrand factor (VWF)-cleaving protease, ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 repeats, member 13). ADAMTS13 deficiency is most commonly acquired due to anti-ADAMTS13 autoantibodies. It can also be inherited in the congenital form as a result of biallelic mutations in the ADAMTS13 gene. In adults, the condition is most often immune-mediated (iTTP) whereas congenital TTP (cTTP) is often detected in childhood or during pregnancy. iTTP occurs more often in women and is potentially lethal without prompt recognition and treatment. Front-line therapy includes daily plasma exchange with fresh frozen plasma replacement and immunosuppression with corticosteroids. Immunosuppression targeting ADAMTS13 autoantibodies with the humanized anti-CD20 monoclonal antibody rituximab is frequently added to the initial therapy. If available, anti-VWF therapy with caplacizumab is also added to the front-line setting. While it is hypothesized that refractory TTP will be less common in the era of caplacizumab, in relapsed or refractory cases cyclosporine A, N-acetylcysteine, bortezomib, cyclophosphamide, vincristine, or splenectomy can be considered. Novel agents, such as recombinant ADAMTS13, are also currently under investigation and show promise for the treatment of TTP. Long-term follow-up after the acute episode is critical to monitor for relapse and to diagnose and manage chronic sequelae of this disease.

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The occurrence of thrombotic thrombocytopenic purpura during treatment of HCV with direct-acting antiviral agents

african journal of gastroenterology and hepatology ◽

10.52378/kxkq8987 ◽

2018 ◽

Vol 1 (1) ◽

pp. 1-9

Author(s):

Amr Hanafy ◽

◽

Waseem Seleem ◽

Salem Mohamed ◽

Keyword(s):

Thrombotic Thrombocytopenic Purpura ◽

Hemolytic Anemia ◽

Peripheral Blood Smear ◽

Hcv Infection ◽

Severe Thrombocytopenia ◽

Direct Acting Antivirals ◽

Thrombocytopenic Purpura ◽

Direct Acting Antiviral ◽

Chronic Hcv ◽

Direct Acting

Background and aim Experts have reported thrombocytopenia linked to chronic liver disease in up to 70% in patients with advanced fibrosis and portal hypertension. Thrombotic thrombocytopenic purpura (TTP) occurrence with HCV infection is a rare and life-threatening event. We aimed to investigate the cause of disturbed conscious level, acute hemolytic anemia, and severe thrombocytopenia in a male patient with chronic HCV and under treatment with direct-acting antivirals. Case report: Development of severe thrombocytopenia, acute hemolytic anemia, neurological symptoms in the form of fits and coma in a 32- year- old man with chronic HCV infection after one week of treatment with direct-acting antivirals (sofosbuvir 400mg PO daily, and daclatasvir 60 mg PO daily). Brain CT was normal, with a negative Coombs test and the presence of schistocytes in the peripheral blood smear. The patient presentation was suggestive of thrombotic thrombocytopenic purpura (TTP). Conclusion: This is a case of TTP after one week of direct-acting antiviral drugs despite the safety profile of these medications. Studying the pathophysiology of TTP after DAAs needs more clarifications.

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Rituximab as pre-emptive treatment in patients with thrombotic thrombocytopenic purpura and evidence of anti-ADAMTS13 autoantibodies

Thrombosis and Haemostasis ◽

10.1160/th07-12-0753 ◽

2009 ◽

Vol 101 (02) ◽

pp. 233-238 ◽

Cited By ~ 62

Author(s):

Sara Gastoldi ◽

Erica Daina ◽

Daniela Belotti ◽

Enrico Pogliani ◽

Paolo Perseghin ◽

...

Keyword(s):

Thrombotic Thrombocytopenic Purpura ◽

Therapeutic Option ◽

Severe Disease ◽

Renal Involvement ◽

First Episode ◽

High Morbidity ◽

Sustained Remission ◽

Adamts13 Activity ◽

Thrombocytopenic Purpura ◽

Haemolytic Anemia

SummaryThrombotic thrombocytopenic purpura (TTP) is a rare and severe disease characterized by thrombocytopenia, microangiopathic haemolytic anemia, neurological and renal involvement associated with deficiency of the von Willebrand factor-cleaving protease, ADAMTS13. Persistence of high titers of anti-ADAMTS13 autoantibodies predisposes to relapsing TTP. Since relapses are associated with high morbidity and mortality rates, the optimal therapeutic option should be a pre-emptive treatment able to deplete anti-ADAMTS13 autoantibodies and avoid relapses. Five patients who presented with persistence of undetectable ADAMTS13 activity and high titers of autoantibodies, were treated with rituximab as pre-emptive therapy during remission. Four of them were affected by relapsing TTP and one was treated after the first episode. ADAMTS13 activity ranging from 15% to 75% with disappearance of inhibitors was achieved after three months in all patients, and persisted >20% without inhibitors at six months. In three patients disease-free status is still ongoing after 29, 24 and six months, respectively. Relapses were documented in two patients during follow-up: in one patient remission lasted 51 months; while in the other patient relapse occurred after 13 months. Results demonstrated that rituximab used as pre-emptive treatment may be effective in maintaining a sustained remission in patients with anti-ADAMTS13 antibodies in whom other treatments failed to limit the production of inhibitors, and suggests that re-treatment with rituximab should be considered when ADAMTS13 activity decreases and inhibitors reappear into the circulation, to avoid a new relapse.

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