Recombinant ADAMTS13 in Congenital Thrombotic Thrombocytopenic Purpura.

BACKGROUND: Congenital thrombotic thrombocytopenic purpura (TTP) results from severe hereditary deficiency of ADAMTS13. The efficacy and safety of recombinant ADAMTS13 and standard therapy (plasma-derived products) administered as routine prophylaxis or on-demand treatment in patients with congenital TTP is not known. METHODS: In this phase 3, open-label, crossover trial, we randomly assigned patients in a 1:1 ratio to two 6-month periods of prophylaxis with recombinant ADAMTS13 (40 IU per kilogram of body weight, administered intravenously) or standard therapy, followed by the alternate treatment; thereafter, all the patients received recombinant ADAMTS13 for an additional 6 months. The trigger for this interim analysis was trial completion by at least 30 patients. The primary outcome was acute TTP events. Manifestations of TTP, safety, and pharmacokinetics were assessed. Patients who had an acute TTP event could receive on-demand treatment. RESULTS: A total of 48 patients underwent randomization; 32 completed the trial. No acute TTP event occurred during prophylaxis with recombinant ADAMTS13, whereas 1 patient had an acute TTP event during prophylaxis with standard therapy (mean annualized event rate, 0.05). Thrombocytopenia was the most frequent TTP manifestation (annualized event rate, 0.74 with recombinant ADAMTS13 and 1.73 with standard therapy). Adverse events occurred in 71% of the patients with recombinant ADAMTS13 and in 84% with standard therapy. Adverse events that were considered by investigators to be related to the trial drug occurred in 9% of the patients with recombinant ADAMTS13 and in 48% with standard therapy. Trial-drug interruption or discontinuation due to adverse events occurred in no patients with recombinant ADAMTS13 and in 8 patients with standard therapy. No neutralizing antibodies developed during recombinant ADAMTS13 treatment. The mean maximum ADAMTS13 activity after recombinant ADAMTS13 treatment was 101%, as compared with 19% after standard therapy. CONCLUSIONS: During prophylaxis with recombinant ADAMTS13 in patients with congenital TTP, ADAMTS13 activity reached approximately 100% of normal levels, adverse events were generally mild or moderate in severity, and TTP events and manifestations were rare. (Funded by Takeda Development Center Americas and Baxalta Innovations; ClinicalTrials.gov number, NCT03393975.).

Unfolding the pathophysiology of congenital thrombotic thrombocytopenic purpura in pregnancy: lessons from a cluster of familial cases.

BACKGROUND: Thrombotic thrombocytopenic purpura (TTP), a rare, potentially life-threatening thrombotic microangiopathy, manifests either as congenital TTP or acquired forms. It is caused by the absence or severe depletion of a disintegrin and metalloproteinase with thrombospondin motifs 13 (ADAMTS13) protease, leading to the accumulation of ultra large von Willebrand factor multimers as well as extensive platelet adhesion and clumping, which can ultimately cause severe secondary end-organ damage. Pregnancy can provoke or exacerbate TTP, leading to maternal and fetal complications. OBJECTIVE: In this report, we focused on pregnancy outcomes in a recently recognized cohort of congenital TTP patients of Bedouin Arab descent in southern Israel who were all homozygous for a novel c.3772delA variant of the ADAMTS13 gene, leading to the clinical manifestations of TTP largely during pregnancy. STUDY DESIGN: All patients presented in this study belong to 2 closely related families of Arab Bedouin descent and were found to be homozygous for a novel ADAMTS13-c.3772delA variant. The cohort consisted of 19 females; 16 of them had congenital TTP and had been pregnant and were thus included. Patient data were collected from electronic medical records. RESULTS: Of note, 13 women from our cohort, who delivered 14 fetuses (owing to 1 twin pregnancy), were diagnosed with congenital TTP following complicated pregnancies, which included recurrent pregnancy loss, stillbirth, early onset preeclampsia (both mild and severe), hemolysis, elevated liver enzymes and low platelet count syndrome, intrauterine growth restriction with abnormal Doppler flow, preterm premature rupture of membranes, and a total perinatal mortality rate of 30.7% (4/13). An additional 3 women, who were diagnosed owing to complications outside of pregnancy and at older ages, experienced TTP during their pregnancies, which occurred before diagnosis. Subsequent pregnancies were treated with fresh frozen plasma leading to a 100% fetal survival rate in the pregnancies that reached fetal viability. All placentas had lesions consistent with maternal vascular underperfusion. However, the severity and frequency of these lesions were lower in the 8 placentas from pregnancies treated with fresh frozen plasma. CONCLUSION: This case series details a distinctive cohort of congenital TTP patients, all homozygous for the same, novel ADAMTS13 variant, who presented with clinical complications during pregnancy and maternal vascular lesions of underperfusion in the placenta. Our findings imply that the variant identified in the ADAMTS13 gene in our cohort may have a specific functional impact on the placenta, and that treatment with fresh frozen plasma during pregnancy ameliorates the course of the disease, leading to a milder phenotype or a normal pregnancy in the majority of cases.

First reported case of congenital thrombotic thrombocytopenic purpura in Taiwan with novel mutation of ADAMTS13 gene.

Congenital thrombotic thrombocytopenic purpura (cTTP) is a rare disease that is defined as biallelic mutations of ADAMTS13 causing persistent absence of ADAMTS13 activity. The confirmed diagnosis requires a genetic study, and cTTP has never been previously reported in Taiwan. Our patient was a 29-year-old Taiwanese woman who presented with severe hyperbilirubinemia at birth. She had severe thrombocytopenia and hemolytic anemia at the age of 1, and another acute TTP event at the age of 7 triggered by an upper airway infection. Regular plasma replacement was started at age 12 based on a presumptive diagnosis of cTTP. Clinical diagnosis of cTTP, with undetectable ADAMTS13 activity and absence of ADAMTS13 inhibitor, was confirmed at age 27. A genetic study showed a previously reported mutation c.1921G to A, inherited from her father, and a maternally inherited, novel mutation at exon 12, c.1435+1dupG, which results in a splicing site change and frame shift. Reports of cTTP from East Asia, except Japan, are scarce. Some prevalent ADAMTS13 mutations are also race or region specific. With this report, we hope to raise awareness among physicians in Taiwan, promote early, proper diagnosis of cTTP, and reveal the true prevalence of cTTP in the Taiwanese population.

Upshaw-Schulman syndrome-associated ADAMTS13 variants possess proteolytic activity at the surface of endothelial cells and in simulated circulation.

ADAMTS13 regulates the hemostatic activity of von Willebrand factor (VWF). Determined by static assays, proteolytic activity <10IU/dL in patient plasma, in absence of ADAMTS13 autoantibodies, indicates Upshaw-Schulman syndrome (USS); the congenital form of Thrombotic Thrombocytopenic Purpura (TTP). We have recently functionally characterized sixteen USS-associated ADAMTS13 missense variants under static conditions. Here, we used two assays under shear flow conditions to analyze the activity of those seven mutants with sufficiently high residual secretion plus two newly identified variants. One assay determines cleavage of VWF strings bound to the surface of endothelial cells. The other, light transmission aggregometry-based assay, mimics degradation of VWF-platelet complexes, which are likely to be present in the circulation during TTP bouts. We found that 100 ng/ml of all variants were able to cleave about 80-90% of VWF strings even though 5 out of 9 exhibited activity ≤1% in the state-of-the-art static assay at the same concentration. These data indicate underestimation of ADAMTS13 activity by the used static assay. In simulated circulation, two variants, with missense mutations in the vicinity of the catalytic domain, exhibited only minor residual activity while all other variants were able to effectively break down VWF-platelet complexes. In both assays, significant proteolytic activity could be observed down to 100 ng/ml ADAMTS13. It is thus intriguing to postulate that most variants would have ample activity if secretion of 10% of normal plasma levels could be achieved.

Congenital thrombotic thrombocytopenic purpura presenting in adulthood with recurrent cerebrovascular events.

Congenital thrombotic thrombocytopenic purpura (cTTP) is a rare, life-threatening disease, characterised by episodes of microangiopathic haemolytic anaemia (MAHA), thrombocytopenia and small vessel thrombosis. We describe a case of cTTP first diagnosed at age 70 years in a female presenting with an acute ischaemic stroke and thrombocytopenia, in whom A Disintegrin And Metalloproteinase with a Thrombospondin type 1 Motif, member 13 (ADAMTS13) levels were <10%, suggestive of thrombotic thrombocytopaenic purpura (TTP). The patient underwent plasma exchange and started rituximab for presumed immune TTP; however, anti-ADAMTS13 antibody titres were negative on two occasions. This, together with a history of pregnancies complicated by presumed disseminated intravascular coagulation, and two previous episodes of sepsis with MAHA, prompted investigation for cTTP, which was confirmed by genetic testing. Despite treatment with infusions of solvent/detergent-treated, virus-inactivated fresh frozen plasma, she has re-presented with further neurological deficit, associated with new infarcts on imaging. cTTP has a varied phenotype which, as demonstrated in this case, can include large vessel occlusion.

Characterization and treatment of congenital thrombotic thrombocytopenic purpura.

Congenital thrombotic thrombocytopenic purpura (cTTP) is an ultra-rare thrombomicroangiopathy caused by an inherited deficiency of a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13). There are limited data on genotype-phenotype correlation; there is no consensus on treatment. We reviewed the largest cohort of cTTP cases, diagnosed in the United Kingdom, over the past 15 years. Seventy-three cases of cTTP were diagnosed, confirmed by genetic analysis. Ninety-three percent were alive at the time of review. Thirty-six percent had homozygous mutations; 64% had compound heterozygous mutations. Two presentation peaks were seen: childhood (median diagnosis age, 3.5 years) and adulthood, typically related to pregnancy (median diagnosis age, 31 years). Genetic mutations differed by age of onset with prespacer mutations more likely to be associated with childhood onset (P = .0011). Sixty-nine percent of adult presentations were associated with pregnancy. Fresh-frozen plasma (FFP) and intermediate purity factor VIII concentrate were used as treatment. Eighty-eight percent of patients with normal blood counts, but with headaches, lethargy, or abdominal pain, reported symptom resolution with prophylactic therapy. The most common currently used regimen of 3-weekly FFP proved insufficient for 70% of patients and weekly or fortnightly infusions were required. Stroke incidence was significantly reduced in patients receiving prophylactic therapy (2% vs 17%; P = .04). Long-term, there is a risk of end-organ damage, seen in 75% of patients with late diagnosis of cTTP. In conclusion, prespacer mutations are associated with earlier development of cTTP symptoms. Prophylactic ADAMTS13 replacement decreases the risk of end-organ damage such as ischemic stroke and resolved previously unrecognized symptoms in patients with nonovert disease.

Risk of diagnostic delay in congenital thrombotic thrombocytopenic purpura.

Essentials Congenital thrombotic thrombocytopenic purpura (cTTP) is a very rare thrombotic microangiopathy. Its rarity and great phenotype heterogeneity may account for misdiagnosis. We report the history of a middle-aged woman with cTTP, misdiagnosed until adulthood. Accurate clinical history is crucial for early diagnosis to prevent long-term sequelae. SUMMARY: Thrombotic thrombocytopenic purpura (TTP) is an acute life-threatening disorder characterized by multiple organ ischemia due to disseminated thrombus formation in the microvasculature. The congenital form of the disease (Upshaw-Schulman syndrome) is related to ADAMTS13 mutations. Adulthood-onset of TTP does not exclude the congenital form of the disease and a diagnostic delay may account for a great morbidity burden in these patients. We describe the case of a middle-aged woman who presented to our attention with a clinical diagnosis of a chronic relapsing form of TTP. The medical history of the patient raised the suspicion of a congenital form of TTP. Phenotype and genotype tests were performed, and clinical diagnosis was confirmed. Upshaw-Schulman syndrome is a rare congenital disease with a great phenotype heterogeneity that can be diagnosed also in adulthood. Accurate clinical history is crucial. Early diagnosis can prevent recurrences and long-term organ damage with long-term sequelae.

Pharmacokinetics of plasma infusion in congenital thrombotic thrombocytopenic purpura.

Essentials Congenital thrombotic thrombocytopenic purpura (TTP) is primarily treated with plasma infusion. We present a pharmacokinetic analysis of ADAMTS-13 in six patients following plasma infusion. A median half-life of 130 h was demonstrated, ranging between 82.6 and 189.5 h. Investigation of interindividual clearance of ADAMTS-13 is necessary to optimize treatment. SUMMARY: Background Congenital thrombotic thrombocytopenic purpura (TTP) is defined by persistent severe deficiency of ADAMTS-13 in the absence of anti-ADAMTS-13 inhibitory antibodies, confirmed by mutational analysis. Replacement of the missing protease prevents disease relapse, primarily using plasma infusion (PI). Objectives, patients and methods There is scant evidence regarding optimal dose and frequency of treatment, which tends to be empirically guided. We present a pharmacokinetic analysis of ADAMTS-13 in six patients with congenital TTP on established regimes following PI. Results We found a median clearance of 25.41 mL h-1 and half-life of 130 h, ranging between 82.6 and 189.5 h (3.4-7.9 days, respectively). All patients reached baseline ADAMTS-13 level within 7-10 days post-plasma. Median ADAMTS-13 activity peak post-PI was 24.05 IU dL-1 . Variation was related to elimination rate, which, in turn, was affected by weight and metabolism, but not to von Willebrand factor antigen or activity levels. Using the pharmacokinetic parameters, we simulated individualized protocols based on PI dose or frequency to target hypothetical optimal plasma levels of ADAMTS-13 of 10 and 50 IU dL-1 , respectively. Results suggest a target trough ADAMTS-13 of 10 IU dL-1 is feasible but 50 IU dL-1 would not be achievable taking into account volume required. Conclusions Further work is needed to compare treatment of congenital TTP with PI vs. recombinant ADAMTS-13. PI may provide longer duration of ADAMTS-13 effect, but is limited by plasma volume required, whereas recombinant therapy can provide a higher ADAMTS-13 peak. We propose that investigation of interindividual clearance of ADAMTS-13 is necessary to optimize treatment and provide the rationale for dose and frequency of prophylaxis.

Relapse of congenital thrombotic thrombocytopenic purpura, after spontaneous remission, in a second-trimester primigravida: case report and review of the literature / Recidiva, após remissão espontânea, de púrpura trombocitopênica trombótica congênita em primigesta no segundo trimestre de gestação: relato de caso e revisão da literatura

ABSTRACT CONTEXT: Thrombotic microangiopathy syndrome or thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) describes distinct diseases sharing common pathological features: microangiopathic hemolytic anemia and thrombocytopenia, without any other apparent cause. CASE REPORT: An 18-year-old second-trimester primigravida presented with a history of fifteen days of intense weakness, followed by diarrhea over the past six days. She reported having had low platelets since childhood, but said that she had never had bleeding or menstrual abnormalities. Laboratory investigation showed anemia with schistocytes, thrombocytopenia and hypohaptoglobulinemia. Red blood cell concentrate and platelet transfusions were performed. The hypothesis of TTP or HUS was put forward and ADAMTS13 enzyme activity was investigated. The patient evolved with increasing platelet counts, even without specific treatment, and she was discharged. One month afterwards, she returned presenting weakness and swollen face and legs, which had developed one day earlier. The ADAMTS13 activity was less than 5%, without presence of autoantibodies. Regarding the two previous admissions (at 9 and 16 years of age), with similar clinical features, there was spontaneous remission on the first occasion and, on the second, the diagnosis of TTP was suspected and plasmapheresis was performed, but ADAMTS13 activity was not investigated. CONCLUSION: To date, this is the only report of congenital TTP with two spontaneous remissions in the literature This report reveals the importance of suspicion of this condition in the presence of microangiopathic hemolytic anemia and thrombocytopenia without any other apparent cause.

RESUMO CONTEXTO: A síndrome de microangiopatia trombótica, ou púrpura trombocitopênica trombótica-síndrome hemolítico urêmica (PTT-SHU), descreve doenças diversas com clínica e achados patológicos comuns: anemia hemolítica microangiopática e trombocitopenia, na ausência de outra causa aparente. RELATO DO CASO: Primigesta de 18 anos no segundo trimestre apresenta-se com quadro de 15 dias de fraqueza intensa seguida por diarreia há seis dias. Relata ter plaquetas baixas desde a infância e nega sangramentos e anormalidades menstruais. Investigação laboratorial identificou anemia com esquizócitos, plaquetopenia e hipo-haptoglobulinemia. Foi realizada transfusão de plaquetas e concentrado de hemácias. A hipótese de PTT ou SHU foi aventada e realizou-se pesquisa da atividade da enzima ADAMTS13. A paciente evoluiu com elevação das plaquetas, mesmo sem tratamento específico, tendo alta. Retornou após um mês da alta com queixa de fraqueza há um dia e inchaço de face e pernas. A atividade da ADAMTS13 foi menor que 5%, sem autoanticorpos. Nas duas internações anteriores (aos 9 e 16 anos), com quadros similares, houve remissão espontânea na primeira internação e, na segunda, o diagnóstico de PTT foi suspeitado e foi realizada plasmaférese, porém sem a pesquisa da atividade da ADAMTS13. CONCLUSÃO: Até esta data, este é único relato de TTP congênita com duas remissões espontâneas na literatura. Este relato revela a importância da suspeição desta patologia na presença de anemia hemolítica microangiopática e trombocitopenia sem outra causa aparente.

Successful kidney transplantation in a patient with congenital thrombotic thrombocytopenic purpura (Upshaw-Schulman syndrome).

BACKGROUND: Congenital thrombotic thrombocytopenic purpura (TTP) may not be recognized until organ failure related to the microvascular thrombosis occurs. Kidney failure may be the initial presenting clinical feature. Kidney transplantation has been contraindicated because of the assumption that the continuing microvascular thrombosis will cause inevitable graft failure. CASE REPORT: We report a 48-year-old nulliparous woman who presented with end-stage kidney disease that was attributed to hypertension. Her past history included a thromboembolic stroke at age 32, for which she was placed on permanent anticoagulation. Immediately after living unrelated-donor kidney transplant, she developed severe hemolysis and acute decline in urine output for which she received red blood cell and platelet transfusions and an infusion of eculizumab (1200 mg). She promptly responded and was discharged on her fifth postoperative day with a serum creatinine level of 1.0 mg/dL. Two weeks later, thrombocytopenia and hemolysis recurred. By this time, undetectable ADAMTS13 activity (<5%) with no demonstrable inhibitor had been reported. She responded rapidly to plasma infusions. Genetic analysis confirmed the diagnosis of congenital TTP, documenting known pathogenic mutations in each of the ADAMTS13 genes. She continued to receive twice-monthly infusions for 4 months. Surveillance kidney biopsies at 6 and 12 months posttransplant demonstrated no evidence of thrombotic microangiopathy or graft rejection. After 2 years of follow-up her creatinine remains stable at 1.0 mg/dL (estimated glomerular filtration rate, 65 mL/min/1.73 m2 ). CONCLUSION: Our experience suggests that kidney transplantation may be an appropriate management for carefully selected patients with congenital TTP who develop end-stage renal disease.

Siblings with congenital thrombotic thrombocytopenic purpura.

Congenital thrombotic thrombocytopenic purpura (TTP) is a rare hereditary deficiency of ADAMTS13 (von Willebrand factor-cleaving protease) characterized by thrombocytopenia and microangiopathic hemolytic anemia. The spectrum of the clinical phenotype is wide, ranging from asymptomatic episodes of thrombocytopenia to life-threatening multiorgan failure. Reportedly, some patients develop isolated thrombocytopenia during childhood. We herein report sibling cases of congenital TTP. An 11-year-old boy with thrombocytopenia accompanied by influenza virus infection was referred to our hospital. He had a history of severe neonatal jaundice. His 15-year-old brother also had recurrent thrombocytopenia with approximately 10 episodes of recurrence since 3 years of age. Their ADAMTS13 activities were low and ADAMTS13 inhibitors were negative, and a gene analysis confirmed the diagnosis of congenital TTP. Notably, congenital TTP should be included in the differential diagnosis, and it is essential to determine the ADAMTS13 activity for pediatric patients with thrombocytopenia of unknown etiology.

Interaction between Multimeric von Willebrand Factor and Complement: A Fresh Look to the Pathophysiology of Microvascular Thrombosis.

von Willebrand factor (VWF), a multimeric protein with a central role in hemostasis, has been shown to interact with complement components. However, results are contrasting and inconclusive. By studying 20 patients with congenital thrombotic thrombocytopenic purpura (cTTP) who cannot cleave VWF multimers because of genetic ADAMTS13 deficiency, we investigated the mechanism through which VWF modulates complement and its pathophysiological implications for human diseases. Using assays of ex vivo serum-induced C3 and C5b-9 deposits on endothelial cells, we documented that in cTTP, complement is activated via the alternative pathway (AP) on the cell surface. This abnormality was corrected by restoring ADAMTS13 activity in cTTP serum, which prevented VWF multimer accumulation on endothelial cells, or by an anti-VWF Ab. In mechanistic studies we found that VWF interacts with C3b through its three type A domains and initiates AP activation, although assembly of active C5 convertase and formation of the terminal complement products C5a and C5b-9 occur only on the VWF-A2 domain. Finally, we documented that in the condition of ADAMTS13 deficiency, VWF-mediated formation of terminal complement products, particularly C5a, alters the endothelial antithrombogenic properties and induces microvascular thrombosis in a perfusion system. Altogether, the results demonstrated that VWF provides a platform for the activation of the AP of complement, which profoundly alters the phenotype of microvascular endothelial cells. These findings link hemostasis-thrombosis with the AP of complement and open new therapeutic perspectives in cTTP and in general in thrombotic and inflammatory disorders associated with endothelium perturbation, VWF release, and complement activation.

Management of thrombotic thrombocytopenic purpura.

Daily therapeutic plasma exchange (TPE) transformed the historically fatal prognosis of acquired, anti-ADAMTS13 antibody-mediated thrombotic thrombocytopenic purpura (TTP), leading to the current overall survival rates of >80%. However, relapses occur in up to 40% of patients and refractory disease with fatal outcomes still occurs, typically within the first days of management. In this context, the introduction of rituximab has been the second major breakthrough in TTP management. Rituximab is now routinely recommended during the acute phase, typically in patients with a suboptimal response to treatment, and increasingly as frontline therapy, with high response rates in the following weeks. In more severe patients, salvage strategies typically include twice daily TPE, pulses of cyclophosphamide, as well as splenectomy in the more desperate cases. In this life-threatening and debilitating disease, relapses can be efficiently prevented in patients with a severe acquired ADAMTS13 deficiency and otherwise in remission with the use of rituximab. In the coming years, the TTP therapeutic landscape should be enriched by original strategies stemming from clinical experience and new agents that are currently being evaluated in large, international, clinical trials. Promising agents under evaluation include caplacizumab (an inhibitor of the glycoprotein-Ib/IX-Von-Willebrand factor axis), N-acetylcysteine, recombinant ADAMTS13, and anti-plasmocyte compounds.

Relapse of congenital thrombotic thrombocytopenic purpura, after spontaneous remission, in a second-trimester primigravida: case report and review of the literature.

CONTEXT: Thrombotic microangiopathy syndrome or thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) describes distinct diseases sharing common pathological features: microangiopathic hemolytic anemia and thrombocytopenia, without any other apparent cause. CASE REPORT: An 18-year-old second-trimester primigravida presented with a history of fifteen days of intense weakness, followed by diarrhea over the past six days. She reported having had low platelets since childhood, but said that she had never had bleeding or menstrual abnormalities. Laboratory investigation showed anemia with schistocytes, thrombocytopenia and hypohaptoglobulinemia. Red blood cell concentrate and platelet transfusions were performed. The hypothesis of TTP or HUS was put forward and ADAMTS13 enzyme activity was investigated. The patient evolved with increasing platelet counts, even without specific treatment, and she was discharged. One month afterwards, she returned presenting weakness and swollen face and legs, which had developed one day earlier. The ADAMTS13 activity was less than 5%, without presence of autoantibodies. Regarding the two previous admissions (at 9 and 16 years of age), with similar clinical features, there was spontaneous remission on the first occasion and, on the second, the diagnosis of TTP was suspected and plasmapheresis was performed, but ADAMTS13 activity was not investigated. CONCLUSION: To date, this is the only report of congenital TTP with two spontaneous remissions in the literature This report reveals the importance of suspicion of this condition in the presence of microangiopathic hemolytic anemia and thrombocytopenia without any other apparent cause.

Severe Hemolysis and Pulmonary Hypertension in a Neonate With Upshaw-Schulman Syndrome.

Pulmonary involvement is extremely rare in thrombotic thrombocytopenic purpura. In this report, we present a girl patient with congenital thrombotic thrombocytopenic purpura, known as Upshaw-Schulman syndrome (USS), complicated with severe hemolysis and pulmonary hypertension (PH). The assay results of a disintegrin-like and metalloprotease with thrombospondin type 1 motifs 13 (ADAMTS13) activity measured by FRETS-VWF73 and ADAMTS13-act-ELISA were different. Hyperbilirubinemia (total bilirubin, 25.3 mg/dL) interfered strongly with the FRETS-VWF73 assay. Plasma levels of ADAMTS13 activity by act-ELISA were <0.5% of normal. The diagnosis of USS was confirmed by ADAMTS13 gene analysis, which showed compound heterozygous mutations of p.G139Vfs*17 and p.I673F. The p.G139Vfs*17 mutation was previously unreported, and its effect in splicing was confirmed by reverse transcription polymerase chain reaction. The patient received oxygen therapy for PH and exchange blood transfusion for severe hemolysis. The PH resolved without specific treatment. Based on these findings, the PH may have been caused by free hemoglobin that scavenged nitrogen oxide or platelet thrombi in the lungs caused by ADAMTS13 deficiency. Thus, severe PH can occur in neonatal patients with USS, and severe hemolysis might result in overestimation of ADAMTS 13 activity. Both possibilities are important for the diagnosis and management of USS.

Síndrome de Upshaw-Schulman. A propósito de un caso condicionado por 3 variantes genómicas / Upshaw-Schulman syndrome. A case based on 3 genomic variants

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Congenital thrombotic thrombocytopenic purpura. / Kongenital trombotisk trombocytopenisk purpura.

BACKGROUND: Congenital thrombotic thrombocytopenic purpura (TTP) is a rare, hereditary disorder. Clinically it presents as episodic microangiopathic haemolytic anaemia and thrombocytopenia with varying degrees of damage to internal organs. The condition may present in neonates, but can also present for the first time in adulthood. The prevalence of congenital TTP is particularly high in Norway, and it is therefore important for Norwegian doctors to be aware of the condition. In this article we review the main characteristics of the disease, including its diagnosis and management, and introduce potential new treatments for the future. METHOD: The article is based on a literature search in PubMed as well as the authors' own research and clinical experience. RESULTS: There was great variation in the severity of congenital TTP: from neonatal mortality to disease-free intervals of several years. Episodes are generally precipitated by a trigger. Acute episodes are treated with plasma infusions, and approximately half of all patients experience frequent episodes and require prophylactic infusions to avoid organ damage. The risk of episodes is greatest in neonates, during pregnancy and in association with infections. INTERPRETATION: There is little research-based evidence regarding long-term prognosis in congenital TTP. There is also a need for guidelines to help identify candidates for prophylactic treatment. An international patient registry would provide useful information and form the basis for better guidelines on the monitoring and treatment of these patients.

Genetic variations in complement factors in patients with congenital thrombotic thrombocytopenic purpura with renal insufficiency.

The congenital form of thrombotic thrombocytopenic purpura (TTP) is caused by genetic mutations in ADAMTS13. Some, but not all, congenital TTP patients manifest renal insufficiency in addition to microangiopathic hemolysis and thrombocytopenia. We included 32 congenital TTP patients in the present study, which was designed to assess whether congenital TTP patients with renal insufficiency have predisposing mutations in complement regulatory genes, as found in many patients with atypical hemolytic uremic syndrome (aHUS). In 13 patients with severe renal insufficiency, six candidate complement or complement regulatory genes were sequenced and 11 missense mutations were identified. One of these missense mutations, C3:p.K155Q mutation, is a rare mutation located in the macroglobulin-like 2 domain of C3, where other mutations predisposing for aHUS cluster. Several of the common missense mutations identified in our study have been reported to increase disease-risk for aHUS, but were not more common in patients with as compared to those without renal insufficiency. Taken together, our results show that the majority of the congenital TTP patients with renal insufficiency studied do not carry rare genetic mutations in complement or complement regulatory genes.