Paroxysmal nocturnal hemoglobinuria and the risk of venous thrombosis: review and recommendations for management of the pregnant and nonpregnant patient

Swiss Survey on current practices and opinions on clinical constellations triggering the search for PNH clones

This national survey investigated the current practice in Switzerland by collecting participants' opinions on paroxysmal nocturnal hemoglobinuria (PNH) clone assessment and clinical practice.

Aim

This study aimed to investigate clinical indications prompting PNH clones' assessment and physician's accessibility of a flow cytometry facility, and also to understand clinical attitudes on the follow-up (FU) of patients with PNH clones.

Methods

The survey includes 16 multiple-choice questions related to PNH and targets physicians with a definite level of experience in the topic using two screener questions. Opinion on clinical management was collected using hypothetical clinical situations. Each participant had the option of being contacted to further discuss the survey results. This was an online survey, and 264 physicians were contacted through email once a week for 5 weeks from September 2020.

Results

In total, 64 physicians (24.2%) from 23 institutions participated (81.3% hematologists and 67.2% from university hospitals). All had access to flow cytometry for PNH clone testing, with 76.6% having access within their own institution. The main reasons to assess for PNH clones were unexplained thrombosis and/or hemolysis, and/or aplastic anemia (AA). Patients in FU for PNH clones were more likely to be aplastic anemia (AA) and symptomatic PNH. In total, 61% of the participants investigated PNH clones repetitively during FU in AA/myelodysplastic syndromes patients, even when there was no PNH clone found at diagnosis, and 75% of the participants tested at least once a year during FU. Opinions related to clinical management were scattered.

Conclusion

The need to adhere to guidelines for the assessment, interpretation, and reporting of PNH clones emerges as the most important finding, as well as consensus for the management of less well-defined clinical situations. Even though there are several international guidelines, clear information addressing specific topics such as the type of anticoagulant to use and its duration, as well as the indication for treatment with complement inhibitors in some borderline situations are needed. The analysis and the discussion of this survey provide the basis for understanding the unmet needs of PNH clone assessment and clinical practice in Switzerland.

Pregnancy in paroxysmal nocturnal hemoglobinuria: from survival to life

Background. Pregnancy in paroxysmal nocturnal hemoglobinuria (PNH) patients has historically been a high-risk situation. The combination of chronic complement-mediated hemolysis caused by the disease and physiological activation of the complement system during pregnancy, significantly worsened the prognosis for the life. For a long time, there were no effective methods for the PNH treatment, and pregnancy in patients seemed to be extremely risky, as it significantly increased the risk of life-threatening complications. The advent of targeted therapy with eculizumab turned the prognosis of this disease upside down: patients began not only to survive, but also to live comparable to healthy people. A comparative analysis of the course and outcomes of pregnancy in patients with PNH treated with eculizumab and in patients without targeted therapy was carried out. Aim. The study was to evaluate the course and outcomes of pregnancy in patients with PNH, depending on the therapeutic approach. Materials and methods. We analyzed data from 57 pregnancies in 49 women (31 used eculizumab, 26 with supportive care only) observed at the Kulakov National Medical Research Center for Obstetrics, Gynecology and Perinatology or with remote consultation (23 clinics from 19 cities of Russia). Results. The high probability of pregnancy complications and its adverse outcomes outside of targeted therapy indicates the vital need for its use: all observations were accompanied by complications of varying severity. The course of pregnancy with the eculizumab is generally more favorable: an apparently higher rate of live births and a lower likelihood of complications are registered. Without increasing the incidence of complications, eculizumab significantly improves pregnancy outcomes for both mother and fetus, and does not adversely affect the health of newborns. Conclusion. Thus, eculizumab allows not only to increase the survival rate of patients with PNH, but also to comprehensively improve their quality of life, including the possibility of safe childbirth.

How I treat paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, clonal, complement-mediated hemolytic anemia with protean manifestations. PNH can present as a hemolytic anemia, a form of bone marrow failure, a thrombophilia, or any combination of the above. Terminal complement inhibition is highly effective for treating intravascular hemolysis from PNH and virtually eliminates the risk of thrombosis, but is not effective for treating bone marrow failure. Here, I present a variety of clinical vignettes that highlight the clinical heterogeneity of PNH and the attributes and limitations of the 2 US Food and Drug Administration-approved C5 inhibitors (eculizumab and ravulizumab) to treat PNH. I review the concept of pharmacokinetic and pharmacodynamic breakthrough hemolysis and briefly discuss new complement inhibitors upstream of C5 that are in clinical development. Last, I discuss the rare indications for bone marrow transplantation in patients with PNH.

Pregnancy in Classical Paroxysmal Nocturnal Hemoglobinuria and Aplastic Anemia-Paroxysmal Nocturnal Hemoglobinuria: A High-Risk Constellation

Pregnancies in paroxysmal nocturnal hemoglobinuria (PNH) are associated with increased morbidity and mortality. Retrospective studies suggest that outcome has improved with the advent of the complement inhibitor eculizumab. To substantiate this assumption we analyzed the data from patients treated in our department since 2009. All patients were included in the International PNH registry and followed prospectively. We identified 16 pregnancies in 9 patients with classical PNH, and two pregnancies in two patients with aplastic anemia (AA)-PNH. In classical PNH, 13 pregnancies were supported by eculizumab. Breakthrough hemolysis occurred in six pregnancies, necessitating an increase in the biweekly eculizumab dose from 900 mg to 1,200–1,800 mg. Red blood cell transfusions were given in six and platelet transfusions in two pregnancies. A Budd-Chiari syndrome and cholecystitis complicated the course of two pregnancies. Four of 13 pregnancies supported by eculizumab ended in spontaneous abortion or stillbirth, and one was prematurely terminated because of fetal trisomy 21. None of the three pregnancies not supported by eculizumab had a successful outcome. Half the deliveries were preterm. None of the patients died, and, in all but one patient, the post-partum period was uneventful. Both pregnancies in patients with AA-PNH took a favorable course. Our results confirm low maternal mortality and frequent breakthrough hemolysis in pregnant PNH patients receiving eculizumab. Fetal mortality and the rate of preterm delivery were higher than reported previously, possibly related to the use of registry data that are likely to reduce the risk of publication and recall biases.

A review of the alternative pathway of complement and its relation to HELLP syndrome: is it time to consider HELLP syndrome a disease of the alternative pathway

Complement is a part of the innate immune system with a critical role in host defense. Although essential for survival, when dysregulated or excessively triggered complement activation can cause tissue damage and drive inflammatory and immune disorders. The alternative pathway of complement (APC) is especially important for survival against infection and can be triggered by a variety of settings: infection, trauma, surgery, or pregnancy. This excessive drive of complement manifest distinctive hemolytic diseases like atypical hemolytic uremic syndrome (aHUS) and paroxysmal nocturnal hemoglobinuria (PNH). These diseases share phenotypic similarities to HELLP syndrome: a hypertensive disorder of pregnancy with hemolysis, elevated liver enzymes, and low platelets. In this manuscript, there will be a brief review of complement activation and a description of important regulator proteins. The review will further discuss pregnancy as a major trigger of the alternative pathway, and how diseases of the APC are treated during pregnancy. Finally, the similarities between HELLP syndrome and diseases of the APC will be examined.

The Extended Use of Eculizumab in Pregnancy and Complement Activation⁻Associated Diseases Affecting Maternal, Fetal and Neonatal Kidneys-The Future Is Now?

Excessive complement activation is involved in the pathogenesis of many diseases and the kidney is an organ with particular susceptibility to complement-mediated injury. Apart from paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS), there are several other diseases with clear evidence of complement activation affecting both maternal and fetal kidneys during pregnancy and causing long-term adverse outcomes. Several novel drugs have been recently developed for blocking the complement cascade, including purified plasma proteins, new monoclonal antibodies, recombinant proteins, small molecules, and small interfering RNA agents. Eculizumab, the humanized monoclonal IgG2/4-antibody targeting C5 was approved by the United States Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for treatment of two rare diseases: PNH in 2007 and aHUS in 2011. There is an increasing number of publications of successful use of eculizumab for off-label indications, e.g., in pregnant women with antiphospholipid syndrome, sickle-cell anemia, and HELLP syndrome. These severe diseases are associated with both high maternal and fetal morbidity and mortality rate and substantial prematurity. Eculizumab has considerably improved overall outcome of patients with PNH and aHUS, enabling safe pregnancy for many women. Prolongation of pregnancy and the use of eculizumab, even for only a few weeks, may protect not only maternal renal function, but also alleviate acute and long-term renal consequences of prematurity in offspring.

Eculizumab in pregnancy: a narrative overview

Pregnancy can be a dangerous trigger for patients with paroxysmal nocturnal hemoglobinuria (PNH), atypical hemolytic uremic syndrome (aHUS), or hemolysis, elevated liver enzymes and low platelet (HELLP) syndrome. Due to the possibility of several serious complications, pregnancy is somewhat discouraged in the presence of the above diseases. Eculizumab is a humanized antibody that may dramatically change the clinical course of PNH, aHUS and HELLP syndrome. However, data on the safety of eculizumab in pregnancy are scarce. In this narrative overview, we summarize current evidence on the use of eculizumab during pregnancy in women with PNH, aHUS and HELLP syndrome. Eculizumab is not present in breast milk, and the levels observed in umbilical cord blood samples are not sufficient to affect the concentrations of complement in newborns. Therefore, eculizumab may be regarded as safe in pregnancy. Nonetheless, given that data on eculizumab in pregnancy are limited, it is not possible to completely exclude risks for both mother and fetus in treating PNH, aHUS and HELLP syndrome.

Eculizumab application during pregnancy in a patient with paroxysmal nocturnal hemoglobinuria: A case report with review of the literature

Eculizumab is highly effective in inhibiting complement activation and has successfully shown to prevent complications and to improve quality of life in patients with paroxysmal nocturnal hemoglobinuria (PNH). Its application during pregnancy showed favorable fetal and maternal outcome in the presented case and has proven to be effective without raising safety concerns.

Paroxysmal nocturnal haemoglobinuria

Paroxysmal nocturnal haemoglobinuria (PNH) is a clonal haematopoietic stem cell (HSC) disease that presents with haemolytic anaemia, thrombosis and smooth muscle dystonias, as well as bone marrow failure in some cases. PNH is caused by somatic mutations in PIGA (which encodes phosphatidylinositol N-acetylglucosaminyltransferase subunit A) in one or more HSC clones. The gene product of PIGA is required for the biosynthesis of glycosylphosphatidylinositol (GPI) anchors; thus, PIGA mutations lead to a deficiency of GPI-anchored proteins, such as complement decay-accelerating factor (also known as CD55) and CD59 glycoprotein (CD59), which are both complement inhibitors. Clinical manifestations of PNH occur when a HSC clone carrying somatic PIGA mutations acquires a growth advantage and differentiates, generating mature blood cells that are deficient of GPI-anchored proteins. The loss of CD55 and CD59 renders PNH erythrocytes susceptible to intravascular haemolysis, which can lead to thrombosis and to much of the morbidity and mortality of PNH. The accumulation of anaphylatoxins (such as C5a) from complement activation might also have a role. The natural history of PNH is highly variable, ranging from quiescent to life-threatening. Therapeutic strategies include terminal complement blockade and bone marrow transplantation. Eculizumab, a monoclonal antibody complement inhibitor, is highly effective and the only licensed therapy for PNH.

Management of thrombosis in paroxysmal nocturnal hemoglobinuria: a clinician's guide

Paroxysmal nocturnal haemoglobinuria (PNH), an ultra-orphan disease with a prevalence of 15.9 per million in Europe, is a life-threatening disorder, characterized by haemolysis, bone marrow failure and thrombosis. Patients with PNH prior to the availability of eculizumab had a median survival of between 10 and 22 years, with thrombosis accounting for 22-67% of deaths. 29-44% of patients had at least one thrombosis. This paper provides a clinician's guide to the diagnosis, management and complications of PNH, with an emphasis on thrombosis.

Eculizumab in the management of paroxysmal nocturnal hemoglobinuria: patient selection and special considerations

Paroxysmal nocturnal hemoglobinuria (PNH) is a nonmalignant clonal disorder resulting from somatic mutation in the PIG-A gene leading to a deficiency of the membrane-anchoring molecule glycosylphosphatidylinositol. The lack of expression of two glycosylphosphatidylinositol-anchored proteins involved in the regulation of the complement system renders PNH erythrocytes susceptible to complement-mediated lysis. Clinical manifestations include thromboembolic disease, chronic kidney injury, pulmonary hypertension, smooth muscle dysfunction, and chronic hemolysis. Until recently, treatment was mainly supportive with most patients suffering from significant morbidity and shortened survival compared to age-matched controls. The development of eculizumab, a humanized monoclonal antibody directed against the terminal complement protein C5, has resulted in dramatic improvements of survival and reduction in complications. In this paper, we review some special considerations pertaining to the use of eculizumab for PNH.

Complement Activation in Placental Malaria

Sixty percent of all pregnancies worldwide occur in malaria endemic regions. Pregnant women are at greater risk of malaria infection than their non-pregnant counterparts and have a higher risk of adverse birth outcomes including low birth weight resulting from intrauterine growth restriction and/or preterm birth. The complement system plays an essential role in placental and fetal development as well as the host innate immune response to malaria infection. Excessive or dysregulated complement activation has been associated with the pathobiology of severe malaria and with poor pregnancy outcomes, dependent and independent of infection. Here we review the role of complement in malaria and pregnancy and discuss its part in mediating altered placental angiogenesis, malaria-induced adverse birth outcomes, and disruptions to the in utero environment with possible consequences on fetal neurodevelopment. A detailed understanding of the mechanisms underlying adverse birth outcomes, and the impact of maternal malaria infection on fetal neurodevelopment, may lead to biomarkers to identify at-risk pregnancies and novel therapeutic interventions to prevent these complications.

Successful pregnancy outcome in paroxysmal nocturnal hemoglobinuria (PNH) following escalated eculizumab dosing to control breakthrough hemolysis

Pregnancy in women with paroxysmal nocturnal hemoglobinuria (PNH) is associated with increased maternal and fetal morbidity and mortality. There is limited published experience regarding therapy of PNH during pregnancy. We describe a case of a 30 year old female with hypoplastic myelodysplastic syndrome and PNH. After two years of treatment with eculizumab, she became pregnant. She developed breakthrough hemolysis at 20 weeks gestation. Pharmacokinetic and pharmacodynamic studies demonstrated a subtherapeutic eculizumab level with absence of complement blockade. Escalation of her eculizumab dose successfully controlled hemolysis and restored therapeutic eculizumab level and activity. She delivered a healthy baby at 36 weeks.

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Pregnancy in PNH cause increased maternal and fetal morbidity & mortality.

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Limited published data regarding the use of eculizumab in pregnancy.

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Breakthrough hemolysis in pregnancy despite standard eculizumab administration.

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Escalated dose of eculizumab is required to achieve therapeutic eculizumab levels.

The complement system and adverse pregnancy outcomes

Adverse pregnancy outcomes significantly contribute to morbidity and mortality for mother and child, with lifelong health consequences for both. The innate and adaptive immune system must be regulated to insure survival of the fetal allograft, and the complement system is no exception. An intact complement system optimizes placental development and function and is essential to maintain host defense and fetal survival. Complement regulation is apparent at the placental interface from early pregnancy with some degree of complement activation occurring normally throughout gestation. However, a number of pregnancy complications including early pregnancy loss, fetal growth restriction, hypertensive disorders of pregnancy and preterm birth are associated with excessive or misdirected complement activation, and are more frequent in women with inherited or acquired complement system disorders or complement gene mutations. Clinical studies employing complement biomarkers in plasma and urine implicate dysregulated complement activation in components of each of the adverse pregnancy outcomes. In addition, mechanistic studies in rat and mouse models of adverse pregnancy outcomes address the complement pathways or activation products of importance and allow critical analysis of the pathophysiology. Targeted complement therapeutics are already in use to control adverse pregnancy outcomes in select situations. A clearer understanding of the role of the complement system in both normal pregnancy and complicated or failed pregnancy will allow a rational approach to future therapeutic strategies for manipulating complement with the goal of mitigating adverse pregnancy outcomes, preserving host defense, and improving long term outcomes for both mother and child.

Increased eculizumab requirements during pregnancy in a patient with paroxysmal nocturnal hemoglobinuria: case report and review of the literature

Paroxysmal nocturnal hemoglobinuria (PNH) results from reduced complement regulatory proteins on hematopoietic cells, predisposing patients to intravascular hemolysis, thrombophilia, and cytopenias. Women diagnosed in pregnancy can experience significant maternofetal complications. Trials of eculizumab in PNH excluded pregnant women. Here, we report the first Canadian patient taken through pregnancy on eculizumab.

Paroxysmal nocturnal hemoglobinuria presenting as cerebral venous sinus thrombosis: a case report

Paroxysmal Nocturnal Hemoglobinuria (PNH) is a rare type of acquired hemolytic anemia that is frequently associated with thrombophilia. It may rarely present with cerebral venous sinus thrombosis, which manifests clinically with signs of raised intracranial pressure and requires lifelong anticoagulation therapy. One such rare presentation was seen in a 28 years old male who had history of recurrent episodes of passing red colored urine and this time presented with severe headache. He was diagnosed to have cerebral venous sinus thrombosis and on further workup was found to be suffering from PNH.

Thrombolytic therapy is effective in paroxysmal nocturnal hemoglobinuria: a series of nine patients and a review of the literature

BACKGROUND

Thrombosis is the major risk factor for death in patients with paroxysmal nocturnal hemoglobinuria. Previous case reports indicate that venous thrombosis in patients with paroxysmal nocturnal hemoglobinuria is amenable to thrombolysis.

DESIGN AND METHODS

We reviewed the outcome of thrombolytic therapy for patients with paroxysmal nocturnal hemoglobinuria who had thromboses refractory to anticoagulation at our institutions.

RESULTS

In this study of 41 patients who had at least one thrombotic event, we confirmed a very high incidence of recurrence despite anticoagulation. Nine patients with thrombosis were regarded as eligible for administration of intravenous tissue plasminogen activator, which was effective in reversing thrombi in all of 15 occasions in which it was given. Serious hemorrhagic complications developed in three cases. At last follow-up visit, of the nine patients treated, three had died, and six were in very good to excellent condition in terms of clinical outcome and radiological findings. The only patient in whom thrombolysis may have contributed to a fatal outcome also had complications of "heparin induced thrombocytopenia with thrombosis", which we diagnosed in three additional patients. In our review of the literature, nine out of 15 patients treated with thrombolysis have had a good outcome.

CONCLUSIONS

Although it is associated with a significant but manageable risk of bleeding, systemic thrombolysis is a highly effective treatment for reversing venous thromboses in patients with paroxysmal nocturnal hemoglobinuria.

The pathophysiology of paroxysmal nocturnal hemoglobinuria and treatment with eculizumab

Paroxysmal nocturnal hemoglobinuria is a rare disorder of hemopoietic stem cells. Affected individuals have a triad of clinical associations – intravascular hemolysis, an increased risk of thromboembolism, and bone marrow failure. Most of the symptoms experienced in this disease occur due to the absence of complement regulatory proteins on the surface of the red blood cells. Complement activation is thus not checked and causes destruction of these cells. Eculizumab is a monoclonal antibody treatment which specifically binds to the complement protein C5, preventing its cleavage, and so halts the complement cascade and prevents the formation of the terminal complement proteins. Eculizumab prevents intravascular hemolysis, stabilizes hemoglobin levels, reduces or stops the need for blood transfusions, and improves fatigue and patient quality of life as well as reducing pulmonary hypertension, decreasing the risk of thrombosis and protecting against worsening renal function. It is not a curative therapy but has a great benefit on those with this rare debilitating condition.

Paroxysmal nocturnal hemoglobinuria and pregnancy before the eculizumab era: the French experience

BACKGROUND

Pregnancy in women with paroxysmal nocturnal hemoglobinuria is rare, with few reports on maternal and fetal mortality rates.

DESIGN AND METHODS

A specific questionnaire designed to solicit data on pregnancies in women with paroxysmal nocturnal hemoglobinuria was sent to all members of the French Society of Hematology in January 2008.

RESULTS

We identified 27 pregnancies in 22 women at 10 French Society of Hematology centers between 1978 and 2008. The median age was 21.5 years at diagnosis of paroxysmal nocturnal hemoglobinuria and 27 years at pregnancy. None of these women had received eculizumab during their pregnancy. Maternal complications, consisting mostly of cytopenias requiring transfusions, occurred in 95% of cases. Two cases of severe aplastic anemia (de novo in one case and relapse in the other) were recorded. No thrombotic events occurred during pregnancy, whereas 4 postpartum thromboses (16%) were recorded, 2 of which were fatal (maternal mortality rate 8%). Most patients received antithrombotic prophylaxis during pregnancy and postpartum (n=16; 64%). Delivery was preterm in 29% of cases, and birth weight was less than 3 kg in 53% of cases. Fetal mortality rate was 4%.

CONCLUSIONS

Pregnancy during paroxysmal nocturnal hemoglobinuria is associated with increased maternal and fetal mortality rates (8% and 4%, respectively, in this series). Maternal mortality is related to postpartum thromboses. Prophylactic anticoagulation is recommended during pregnancy and for six weeks postpartum.

How I treat paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare clonal blood disorder that manifests with hemolytic anemia, bone marrow failure, and thrombosis. Many of the clinical manifestations of the disease result from complement-mediated intravascular hemolysis. Allogeneic bone marrow transplantation is the only curative therapy for PNH. Eculizumab, a monoclonal antibody that blocks terminal complement activation, is highly effective in reducing hemolysis, improving quality of life, and reducing the risk for thrombosis in PNH patients. Insights into the relevance of detecting PNH cells in PNH and other bone marrow failure disorders are highlighted, and indications for treating PNH patients with bone marrow transplantation and eculizumab are explored.

Microvascular thrombosis in the hepatic vein of a patient with paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by complement-mediated hemolysis, venous thrombosis, and bone marrow failure. In May 2003, a 33-year-old man was admitted to a hospital with right hypochondralgia and fever. He had a history of aplastic anemia. The patient's diagnosis of diffuse microvessel thrombosis in the hepatic vein due to an unknown cause was derived from the findings of a contrast-enhanced computed tomography examination of the abdominal region, angiographic evaluation of abdominal vessels, and pathohistologic examination of a liver biopsy sample. The patient was subsequently treated with warfarin. The abdominal pain and fever continued, however, and anemia gradually appeared. In April 2004, the patient was referred to our hospital to examine the cause of the thrombosis. On admission, slight anemia and a low serum haptoglobin level were observed. A flow cytometry evaluation of CD55 and/or CD59, CD59, and CD48 expression in erythrocytes, granulocytes, and monocytes, respectively, showed that the respective proportions of negative populations were 5.6%, 97.1%, and 96.2%. The patient then received a diagnosis of aplastic anemia/PNH syndrome, which had caused the hemolytic anemia and thrombosis, although no hemoglobinuria had been observed during his clinical course. This patient is, to our knowledge, the first reported case of a PNH patient with thrombosis present only in hepatic microvessels and not in hepatic large vessels, in spite of the presence of few hemolytic events.

Paroxysmal nocturnal hemoglobinuria in a girl with hemolysis and "hematuria"

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare disorder of unknown frequency. In its classic form, PNH is characterized by hemolysis accompanied by nocturnal hemoglobinuria. The clinical course is unpredictable and may vary from severe hemolysis and recurrent venous thrombosis to latent periods with milder symptoms. We report a 15-year-old girl with hemolytic episodes, abdominal pain, and passage of dark urine. Hemoglobinuria was demonstrated by a "blood"-positive dipstick test in the absence of red blood cells in the urinary sediment. The diagnosis of PNH was confirmed by flow cytometry.

Clinical manifestations of paroxysmal nocturnal hemoglobinuria: present state and future problems

The clinical pathology of paroxysmal nocturnal hemoglobinuria (PNH) involves 3 complications: hemolytic anemia, thrombosis, and hematopoietic deficiency. The first 2 are clearly the result of the cellular defect in PNH, the lack of proteins anchored to the membrane by the glycosylphosphatidylinositol anchor. The hemolytic anemia results in syndromes primarily related to the fact that the hemolysis is extracellular. Thrombosis is most significant in veins within the abdomen, although a number of other thrombotic syndromes have been described. The hematopoietic deficiency may be the same as that in aplastic anemia, a closely related disorder, and may not be due to the primary biochemical defect. The relationship to aplastic anemia suggests a nomenclature that emphasizes the predominant clinical manifestations in a patient. This relationship does not explain cases that appear to be related to myelodysplastic syndromes or the transition of some cases of PNH to leukemia. Treatment, except for bone marrow transplantation, remains noncurative and in need of improvement.

Paroxysmal nocturnal hemoglobinuria in pregnancy

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hemolytic anemia in which a defect of glycophosphatidylinositol (GPI)-anchored proteins in the cell membrane of bone marrow stem cells leads to increased sensitivity of the red cells to complement, causing intravascular hemolysis and hemoglobinuria. Other clinical features of this disease are cytopenia and an increased frequency of thrombotic events. We report a case of a pregnant woman with PNH on high-dosage anticoagulation therapy, the follow-up during the pregnancy, the delivery and the postpartum period. The obstetric literature on women with PNH is reviewed, the maternal and fetal risks are evaluated and the management of pregnancies and deliveries in such patients are discussed. During the pregnancy our patient was hypertransfused and used anticoagulation treatment. A healthy child was delivered in week 37 by cesarean section because of premature rupture of the membranes, unsuccessful induction and intrauterine infection. Because of bleeding problems a hysterectomy also had to be performed. In the postpartum period the patient developed her second episode of a liver vein thrombosis. She recovered gradually and 18 months after the delivery her disease is now in a stable phase. The literature shows a high maternal morbidity and mortality among pregnant PNH patients. Fetal wastage and prematurity rate are also high. Pregnancy in patients with PNH represents a high-risk situation for both the mother and the child and should not be recommended. A pregnant PNH woman should be followed closely by both obstetricians and hematologists.