Severe Pyruvate Kinase Deficiency Research Articles

293 - Lentiviral-Mediated Gene Therapy for Severe Pyruvate Kinase Deficiency: Results from an Ongoing Global Phase 1 Study

293 - Lentiviral-Mediated Gene Therapy for Severe Pyruvate Kinase Deficiency: Results from an Ongoing Global Phase 1 Study

Lentiviral-mediated Gene Therapy for Adults and Children with Severe Pyruvate Kinase Deficiency: Results from an Ongoing Global Phase 1 Study

Lentiviral-mediated Gene Therapy for Adults and Children with Severe Pyruvate Kinase Deficiency: Results from an Ongoing Global Phase 1 Study

Pyruvate kinase deficiency: A rare cause of hemolytic anemia: A case report from North-Eastern India

Pyruvate kinase, liver and RBC (PKLR) gene located on chromosome 1q21 encodes erythrocyte pyruvate kinase enzyme. Pyruvate kinase conveys the concluding tread of the glycolytic pathway, along with production of the 50% red cell total adenosine triphosphate. Pyruvate kinase deficiency (PKD) is a rare autosomal recessive disorder causing congenital non-spherocytic hemolytic anemia (CNSH). Biallelic pathogenic variation in the PKLR gene is responsible for PKD. It is the most common glycolytic defect resulting in CNSH. This case report highlights different pathogenic variants in PKLR gene detected in a patient having severe PKD.

Lentiviral Mediated Gene Therapy for Pyruvate Kinase Deficiency: Interim Results of a Global Phase 1 Study for Adult and Pediatric Patients

▪Background: Pyruvate kinase deficiency (PKD) is a rare inherited hemolytic anemia caused by mutations in the PKLR gene resulting in decreased red cell pyruvate kinase activity and impaired erythrocyte metabolism. Manifestations include anemia, reticulocytosis, splenomegaly and iron overload, and may be life-threatening in severely affected individuals. PKD represents a significant unmet medical need as current treatments are palliative and limited to blood transfusions, chelation therapy, and splenectomy which are associated with significant side effects. Preclinical studies in a clinically relevant PKD murine model have demonstrated that infusion of gene-modified Lin− bone marrow (BM) cells may ameliorate PKD phenotype. Based on compelling preclinical data, a global Phase 1 clinical trial RP-L301-0119 (NCT04105166) is underway to evaluate the feasibility and safety of lentiviral mediated gene therapy in adult and pediatric subjects with severe PKD.Methods: Six adult and pediatric patients with severe PKD (defined as severe and/or transfusion-dependent anemia despite prior splenectomy) will be enrolled. Peripheral blood (PB) hematopoietic stem cells (HSCs) are collected on 2 consecutive days via apheresis after mobilization with granulocyte-colony stimulating factor (G-CSF) and plerixafor. HSCs are enriched, transduced with PGK-coRPK-WPRE lentiviral vector (LV), and cryopreserved. Following release testing of the investigational product (IP), RP-L301, myeloablative therapeutic drug monitoring (TDM) busulfan is administered over 4 days. RP-L301 is then thawed and infused. Patients are followed for safety assessments, including replication competent lentivirus (RCL) and insertion site analysis (ISA), and for efficacy parameters including PB and BM genetic correction, decrease in transfusion requirements, clinically significant improvement in anemia, and reduction of hemolysis for 2 years post-infusion.Results: As of May 2021, 2 adult patients with severe anemia have received RP-L301. Patient 1 (age 31 years) received 3.9x106 CD34+ cells/kg with mean vector copy number (VCN) of 2.73. Patient 2 (age 47 years) received 2.4x106 CD34+ cells/kg with mean VCN of 2.08. Despite baseline hemoglobin (Hb) levels in the 7.0-7.5 g/dL range, both patients displayed normal-range hemoglobin (Hb), improved hemolysis markers, and have required no red blood cell transfusions post-engraftment at 9- and 6- months follow-up. Both report improved quality of life. PB mononuclear cell VCNs for both patients were >2.0 at last evaluated timepoint (6- and 3-months post-treatment, respectively). No serious adverse events have been attributed to RP-L301. Updated safety and efficacy data will be presented.Conclusions: Hematopoietic stem cell mobilization using G-CSF and plerixafor is feasible and effective in adult PKD patients. RP-L301 was successfully manufactured to meet the required specifications for the Phase 1 clinical study and administered without short-term infusion related complications. Efficacy was demonstrated by normalized Hb associated with engraftment confirmed by PB and BM VCN. DisclosuresShah: OrchardTherapeutics: Membership on an entity's Board of Directors or advisory committees, Other: Dr. Shah currently serves on the medical advisory board for Orchard Therapeutics . Navarro: Rocket Pharmaceuticals, Inc.: Current equity holder in publicly-traded company, Other: Dr. Navarro has licensed medicinal products and receives research funding and equity from Rocket Pharmaceuticals, Inc., Patents & Royalties, Research Funding. Sevilla: Miltenyi: Consultancy; Novartis: Consultancy; Amgen: Consultancy; Rocket Pharmaceuticals, Inc.: Consultancy, Other: J.Sevilla is an inventor on patents on lentiviral vectors filed by CIEMAT, CIBERER and Fundación Jiménez Díaz, and may be entitled to receive financial benefits from the licensing of such patents.; SOBI: Consultancy. Glader: Agios: Consultancy. Quintana Bustamante: Rocket Pharmaceuticals, Inc.: Current equity holder in publicly-traded company. Beard: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Law: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Zeini: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Choi: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Nicoletti: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Rao: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Bueren: Rocket Pharmaceuticals, Inc.: Consultancy, Other: J.Bueren is an inventor on patents on lentiviral vectors filed by CIEMAT, CIBERER and Fundación Jiménez Díaz, may be entitled to receive financial benefits from the licensing of such patents and receives funding for research., Patents & Royalties, Research Funding. Schwartz: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Segovia: Rocket Pharmaceuticals, Inc.: Consultancy, Research Funding.

Lentiviral Mediated Gene Therapy for Pyruvate Kinase Deficiency: A Global Phase 1 Study for Adult and Pediatric Patients

Introduction: Pyruvate Kinase Deficiency (PKD) is a rare inherited hemolytic anemia that is caused by mutations in the PKLR gene leading to decreased red cell pyruvate kinase (RPK) activity and impaired erythrocyte metabolism. The disorder is characterized by anemia, reticulocytosis, splenomegaly and iron overload, and may be life-threatening in severely affected individuals. PKD represents a significant unmet medical need as current therapies are palliative and limited to chronic blood transfusions, iron chelation therapy, and splenectomy. The side effects of these supportive treatments include iron overload, end-organ damage and increased infection risks. AG-348, an allosteric activator of RPK, is under evaluation in clinical trials, predominantly in less severely-afflicted transfusion-independent patients. Allogeneic hematopoietic stem cell transplantation (HSCT) has been performed in selected cases and resulted in transfusion independence, suggesting that the disorder may be reversed when an adequate level of hematopoietic stem and progenitor cells (HSPCs) harboring a corrected PKLR gene engraft in the bone marrow (BM). The therapeutic efficacy of allogeneic transplant is limited by the availability of a suitable donor and transplant-associated toxicities. Preclinical studies conducted in a clinically relevant PKD murine model have demonstrated the safety and efficacy of Lin- BM cells transduced with the therapeutic lentiviral vector, PGK-coRPK-WPRE, in ameliorating the PKD phenotype. More specifically, transplantation of transduced cells resulted in increased erythrocyte survival, decreased reticulocytosis, and improvement in the secondary manifestations of hemolytic anemia, including splenomegaly and hepatic iron overload. Based on compelling preclinical data, a global Phase 1 clinical trial RP-L301-0119 (clinicaltrials.gov#NCT04105166) is underway to evaluate the feasibility and safety of lentiviral mediated gene therapy in adults and pediatric subjects with severe PKD. Methods: 6 subjects with severe PKD (defined as having a history of severe and/or transfusion-dependent anemia despite prior splenectomy) will be enrolled in the Phase 1 study; the first 2 subjects will be adults (age ≥18-<50 years), followed by 2 older pediatric subjects (age ≥12-17 years) once initial safety has been established. Subsequently, 2 younger pediatric subjects (age ≥8-11 years) will be enrolled. Peripheral blood (PB) hematopoietic stem cells are collected on two consecutive days via apheresis after mobilization with granulocyte-colony stimulating factor (G-CSF) and plerixafor. CD34+ HSPCs are enriched, transduced with PGK-coRPK-WPRE lentiviral vector (LV), and cryopreserved. Following final release testing of the investigational product (IP), RP-L301, myeloablative conditioning with therapeutic drug monitoring (TDM)-guided busulfan is administered over 4 days. RP-L301 is then thawed and infused. Patients are followed for safety assessments, including replication competent lentivirus (RCL) and insertion site analysis (ISA), and for efficacy parameters including PB and BM genetic correction, decrease in transfusion requirements, clinically significant improvement in anemia, and reduction of hemolysis. Results: An adult female PKD subject (age 31 years) with significant anemia and transfusion requirement has received treatment as of July 2020. Mobilization and apheresis procedures were performed successfully and busulfan conditioning was administered at the target area under the curve (AUC). IP consisted of 3.9×106 CD34+ cells/kg body weight, with a mean vector copy number (VCN) of 2.73. Safety and preliminary efficacy results will be available at the time of presentation. Conclusions: Efficacy in pre-clinical models indicates promising potential for clinical gene therapy in severe PKDHematopoietic stem cell mobilization using G-CSF and plerixafor appears feasible and effective in adult PKD patientsIP was successfully manufactured to meet the required specifications for the Phase 1 clinical study and administered without short-term infusion related complications Disclosures Navarro: Rocket Pharmaceuticals, Inc.: Current equity holder in publicly-traded company, Other: SN has licensed medicinal products and receives research funding and equity from Rocket Pharmaceuticals, Inc., Patents & Royalties, Research Funding. Sevilla:Rocket Pharmaceuticals, Inc.: Consultancy, Current equity holder in publicly-traded company. Glader:Agios Pharmaceuticals, Inc.: Consultancy. Beard:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Law:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Zeini:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Choi:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Nicoletti:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Bueren:Rocket Pharmaceuticals, Inc.: Consultancy, Current equity holder in publicly-traded company, Other: Consultant for Rocket Pharmaceuticals, Inc. and has licensed medicinal products and receives research funding and equity from this company., Patents & Royalties, Research Funding. Rao:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Schwartz:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Segovia:Rocket Pharmaceuticals, Inc.: Consultancy, Current equity holder in publicly-traded company, Other: Consultant for Rocket Pharmaceuticals, Inc. and has licensed medicinal products and receives research funding and equity from the Company., Patents & Royalties, Research Funding.

Correction of the Energetic Defects in Pyruvate Kinase Deficiency through Genome Editing in Hematopoietic Stem and Progenitor Cells

Pyruvate kinase deficiency (PKD) is an autosomal recessive disorder caused by mutations in the PKLR gene that lead to a reduction of the erythroid pyruvate kinase (RPK) protein activity, which causes an energetic imbalance in PKD erythroid cells. This disease is associated with reticulocytosis, splenomegaly and iron overload, and may be life-threatening in severely affected patients. In selected cases, allogeneic Hematopoietic Stem Cell Transplantation has been shown to correct the disorder. Therefore, autologous HSCT of genetically corrected cells will offer a durable and curative therapeutic option. In fact, a global Phase I clinical trial (clinicaltrials.gov #NCT04105166) is underway to evaluate the feasibility and safety of lentiviral mediated gene therapy with severe PKD. Looking for a guided integration of the exogenous therapeutic DNA sequences, herein we conducted a gene editing approach to correct PKD in human Hematopoietic Stem Cells (HSCs). We developed a knock-in approach to insert either a TurboGFP expression cassette or a promotor-less therapeutic codon optimized RPK cDNA (coRPK) at the genomic starting site of the PKLR gene, a gene editing strategy that will correct most of the mutations present in PKD patients. This gene editing approach combines RNP nucleofection and adeno-associated viral vector (AAV6) mediated delivery of homologous donors. In order to assess the safety of the proposed gene editing approach, we performed GUIDE-Seq and rhAmpSeqTM analyses of different single guide RNAs targeting the PKLR starting site. We found PKLR sgRNAs that showed a high targeting efficiency, up to 40% targeted hematopoietic progenitors (in vitro semisolid colony forming units) and a safety profile, with no off-targets detected above threshold values (0.1%) and in the absence of cellular toxicity, when applied to healthy cord blood CD34+ (CB-CD34+) cells. These gene-edited CB-CD34+ cells engrafted efficiently in both primary and secondary immunodeficient NSG recipient mice, demonstrating the gene editing in long-term hematopoietic repopulating HSCs. Furthermore, we evaluated the therapeutic potential of this gene editing strategy to restore the energetic imbalance in erythroid cells derived from PKD patients. CD34+ cells from 4 different PKD patients, were purified, nucleofected with PKLR sgRNA and transduced with AAV-coRPK donor. In vitro differentiated erythroid cells derived from edited PKD CD34+ expressed coRPK mRNA and restored their energetic defect up to normal values obtained in in vitro differentiated erythroid cells from healthy donor cells. Moreover, gene edited mobilized Peripheral Blood CD34+ (mPB-CD34+) cells from a PKD patient engrafted efficiently in immunodeficient NBSGW mice, having human cells that showed the specific integration of coRPK donor 2 months post-transplant. Overall, these results demonstrate the feasibility and safety of PKLR gene editing in human HSPCs and, therefore, its potential clinical application for the treatment of PKD patients. Disclosures Dever: Integral Medicines: Current Employment. Turk:Integrated DNA Technologies, Inc. (IDT): Current Employment, Current equity holder in publicly-traded company. Bianchi:Agios Pharmaceuticals: Other: Scientific Advisor. Behlke:Integrated DNA Technologies, Inc. (IDT): Current Employment, Current equity holder in publicly-traded company. Bueren:Rocket Pharmaceuticals, Inc.: Consultancy, Current equity holder in publicly-traded company, Other: Consultant for Rocket Pharmaceuticals, Inc. and has licensed medicinal products and receives research funding and equity from this company., Patents & Royalties, Research Funding. Segovia:Rocket Pharmaceuticals, Inc.: Consultancy, Current equity holder in publicly-traded company, Other: Consultant for Rocket Pharmaceuticals, Inc. and has licensed medicinal products and receives research funding and equity from the Company., Patents & Royalties, Research Funding.

Successful allogeneic bone marrow transplantation using immunosuppressive conditioning regimen for a patient with red blood cell transfusiondependent pyruvate kinase deficiency anemia.

Pyruvate kinase deficiency (PKD) is the rare glycolytic enzyme defect causing hemolytic anemia. Treatments are mainly red cell transfusion and/or splenectomy, leading to iron overload. Allogeneic bone marrow transplantation (BMT) is alternatively curative treatment for severe PKD. The intensity of conditioning is often controversial because of higher risk of graft failure and organ damage. Here, we present a transfusion-dependent PKD patient undergoing BMT from an HLA-identical sibling using intensively immunosuppressive conditioning regimen. This report suggests that BMT using immunosuppressive conditioning regimen may be a feasible and effective treatment for patients with severe PKD with iron overload. We suggest the timing of the transplantation at an earlier age in severe PKD predicted from gene mutation is preferred before cumulative damage of transfusion.

Characterization of the Severe Phenotype of Pyruvate Kinase Deficiency

Background: Pyruvate kinase deficiency (PKD) is the most common cause of chronic hereditary non-spherocytic hemolytic anemia. The spectrum of disease in PKD is broad, ranging from an incidentally discovered mild anemia to a severe transfusion-dependent anemia. Splenectomy partially ameliorates the anemia and reduces the transfusion burden in the majority of patients. Because hemoglobin poorly correlates with symptoms in PKD, transfusion requirements are typically used clinically to classify disease severity with those who are regularly transfused despite splenectomy recognized as the most severely affected subgroup. Aim: To compare demographics, complications, and laboratory results between the most severely-affected PKD patients (those that are splenectomized and regularly transfused) with non-regularly transfused splenectomized PKD patients. Methods: After ethics committee approval, patients were enrolled on the PKD Natural History Study, a prospective 30 site international study. All patients had molecularly confirmed PKD. Only splenectomized patients were included in the analysis. Transfusion frequency was observed over a 3-year period. Patients were divided into two groups based on transfusion frequency: the severe phenotype group was defined as those who receive regular transfusions (≥6 discrete red cell transfusion episodes per year) and the control group did not receive regular transfusions. Phenotype stability over the 3-year period was also assessed. Results: 154 splenectomized patients with PKD were included: 30 patients in the severe PKD phenotype group and 124 patients in the comparison PKD group. Results of the analysis comparing the two groups are described in the Table. Severely affected patients were more likely to be female (77% versus 51%, p=0.013), older at the time of splenectomy (median age: 5 versus 3.6, p=0.011), have iron overload (93% vs. 51%, p<0.0001), have received chelation therapy (90% vs. 42%, p<0.0001), and had more lifetime transfusions (median: 77 versus 15, p<0.0001). Rates of other PKD complications including pulmonary hypertension, extramedullary hematopoiesis, liver cirrhosis, endocrinopathy, and bone fracture appear similar between the two groups. Laboratory values, including hemoglobin, total bilirubin, normalized PK enzyme activity, and median absolute reticulocyte count appear similar between the two groups. The underlying genetic mutation patterns (missense mutations versus non-missense mutations) were also similar between the groups. Phenotype stability over time was highly variable: of the patients with a severe phenotype at enrollment, 62% had a severe phenotype during the first follow-up year and 39% had a severe phenotype at the second follow-up year. Conclusions: Patients with PKD who are regularly transfused despite splenectomy appeared to have similar rates of PKD-associated complications (except for iron overload) and similar relevant laboratory values and genotypes when compared to those who are not regularly transfused after splenectomy. The similarity observed between severe phenotype patients and comparison patients with PKD may result from a protective effect of transfusion (e.g. reduction of bone fractures and extramedullary hematopoiesis) or could suggest transfusion-dependence is an artificial signifier of disease severity, reflective of provider practices and patient symptoms rather than an actual distinct phenotype. Transfusion requirements in severe PKD appear to fluctuate significantly over time. Disclosures Al-Samkari: Dova: Consultancy, Research Funding; Agios: Consultancy, Research Funding; Moderna: Consultancy. van Beers:RR Mechatronics: Research Funding; Agios Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Research Funding. Barcellini:Agios: Consultancy, Other: Advisory board; Apellis: Consultancy; Incyte: Consultancy, Other: Advisory board; Bioverativ: Consultancy, Other: Advisory board; Novartis: Research Funding, Speakers Bureau; Alexion: Consultancy, Research Funding, Speakers Bureau. Eber:Agios Pharmaceuticals, Inc.: Consultancy. Glader:Agios Pharmaceuticals, Inc: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Chonat:Alexion: Other: advisory board; Agios Pharmaceuticals, Inc.: Other: advisory board. Kuo:Pfizer: Consultancy; Novartis: Consultancy, Honoraria; Celgene: Consultancy; Agios: Consultancy; Alexion: Consultancy, Honoraria; Apellis: Consultancy; Bioverativ: Other: Data Safety Monitoring Board; Bluebird Bio: Consultancy. Despotovic:Dova: Honoraria; Novartis: Research Funding; Amgen: Research Funding. Kwiatkowski:Celgene: Consultancy; Terumo: Research Funding; Apopharma: Research Funding; bluebird bio, Inc.: Consultancy, Research Funding; Agios: Consultancy; Imara: Consultancy; Novartis: Research Funding. Thompson:Baxalta: Research Funding; Novartis: Consultancy, Research Funding; bluebird bio, Inc.: Consultancy, Research Funding; Celgene: Consultancy, Research Funding. Ravindranath:Agios Pharmaceuticals, Inc.: Other: I am site PI on several Agios-sponsored studies, Research Funding. Rothman:Pfizer: Consultancy, Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Agios: Honoraria, Research Funding. Verhovsek:Sickle Cell Awareness Group of Ontario: Membership on an entity's Board of Directors or advisory committees; Sickle Cell Disease Association of Canada: Membership on an entity's Board of Directors or advisory committees, Research Funding; Canadian Haemoglobinopathy Association: Membership on an entity's Board of Directors or advisory committees; Vertex: Consultancy. Kunz:Novartis: Membership on an entity's Board of Directors or advisory committees. Sheth:CRSPR/Vertex: Other: Clinical Trial Steering committee; Apopharma: Other: Clinical trial DSMB; Celgene: Consultancy. London:United Therapeutics: Consultancy; ArQule, Inc: Consultancy. Grace:Novartis: Research Funding; Agios Pharmaceuticals, Inc: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Siblings with severe pyruvate kinase deficiency and a complex genotype.

Siblings presented as neonates with severe jaundice and transfusion-dependent hemolytic anemia. Next-generation sequencing revealed both to have three heterozygous mutations in the gene encoding erythrocyte pyruvate kinase (PKLR), plus a heterozygous splice mutation in the beta-spectrin gene (SPTB). In addition, both have a different 5th mutation in a gene encoding other erythrocyte membrane proteins. The asymptomatic parents and all three asymptomatic siblings have different sets of these mutations. © 2016 Wiley Periodicals, Inc.

Etiology and Management of Splenic Infarction and Splenic Vein Thrombosis: Unusual Causes of Abdominal Pain in Sickle Cell Trait Patient

AbstractAbstract 4775Abdominal pain is a common complaint among all ages of patients. Splenic infarction and splenic vein thrombosis are rare causes of abdominal pain, usually presenting as left-sided abdominal pain associated with fever, nausea or vomiting, and elevated white blood cell count. CT scan is currently the preferred diagnostic test. Once the diagnosis is identified, the etiology of splenic infarction and/or splenic vein thrombosis should be elicited.Retrospective chart review was conducted in all the patients admitted to our hospital from 2000 till now. Four cases of splenic infarction and/or splenic vein thrombosis were identified (4 males, average age of 45 years, range from 38 to 52 years). Case 1, a 45-year-old male with sickle cell trait (HbS of 38.7%), presented with left upper quadrant pain after 5-hour flight and alcohol binge prior to flight. CT showed splenic infarct and splenic vein thrombosis. Patient received aggressive hydration, abdominal pain resolved and was discharged home. Case 2, a 52-year-old male with renal cell carcinoma, presented with generalized abdominal pain. CT showed splenic infarct. Patient was treated with Coumadin, and routinely followed-up at Oncology clinic. Case 3, a 38-year old male with alcohol abuse and chronic pancreatitis, presented with recurrent abdominal pain and hypersplenism. CT showed splenic vein thrombosis, and the patient underwent splenectomy. Case 4, a 45-year-old male with acute pancreatitis, presented with epigastric pain. CT showed splenic vein thrombosis, and the patient was treated with Coumadin.It is important to reveal the underlying causes for splenic infarction and/or splenic vein thrombosis. Splenic infarction can occur in a variety of settings, including hemoglobinopathy (especially sickle cell disease), hypercoagulable state, embolic disease, malignancy and myeloproliferative disorders. Pancreatitis and pancreatic cancer are the most common causes of splenic vein thrombosis. In general, splenic infarction and/or splenic vein thrombosis can be managed safely with medical treatment, including hydration, oxygenation and pain management. Coumadin can be considered in cancer patients with splenic infarction and in patients with splenic vein thrombosis. Splenectomy is indicated in patients with hypersplenism, splenic sequestration crisis, splenic abscess, splenic rupture, and massive splenic infarction.Splenic infarction in sickle cell disease is usually small and repetitive, leading ultimately to autosplenectomy. Splenic infarction in sickle cell trait is rare. High altitude, vigorous exercise, airplane flight, coexistence with thalassemia or hereditary spherocytosis or severe pyruvate kinase deficiency, can precipitate infarction. Interestingly in our first case, the patient with sickle cell trait developed splenic infarction and non-occlusive thrombus in the distal splenic vein after 5-hour flight. It is possible that the hypoxia associated with the commercial flight caused conformational changes in sickle cells, leading to red blood cells sluggish in the splenic red pulp, and eventually leading to splenic infarction. The alcohol binge resulted in dehydration and hemostasis, leading to splenic vein thrombosis, further perpetuating the vicious cycle. Therefore, we recommend adequate hydration and in-flight oxygen supplementation for sickle cell trait patients taking airplane flight. Further studies need to be done to confirm our hypothesis. Disclosures:No relevant conflicts of interest to declare.

Pyruvate kinase deficiency associated with severe liver dysfunction in the newborn

Significant hyperbilirubinaemia, anemia, and splenomegaly are common features in patients with severe haemolysis due to pyruvate kinase (PK) deficiency. Until now, severe neonatal PK deficiency has not been associated with fatal liver disease at this age. We present two neonatal cases of severe PK deficiency complicated with progressive fatal liver disease. The patients presented with severe haemolysis, progressive cholestasis, and hepatosplenomegaly, and both patients ultimately developed liver failure at a very young age. Despite extensive investigations, no specific explanation for liver disease and failure was found. We suggest that the PK deficiency itself directly led to liver dysfunction.

Disruption of a novel regulatory element in the erythroid-specific promoter of the human PKLR gene causes severe pyruvate kinase deficiency

We established the molecular basis for pyruvate kinase (PK) deficiency in a white male patient with severe nonspherocytic hemolytic anemia. The paternal allele exhibited the common PKLR cDNA sequence (c.) 1529G>A mutation, known to be associated with PK deficiency. On the maternal allele, 3 in cis mutations were identified in the erythroid-specific promoter region of the gene: one deletion of thymine -248 and 2 single nucleotide substitutions, nucleotide (nt) -324T>A and nt -83G>C. Analysis of the patient's RNA demonstrated the presence of only the 1529A allele, indicating severely reduced transcription from the allele linked to the mutated promoter region. Transfection of promoter constructs into erythroleukemic K562 cells showed that the most upstream -324T>A and -248delT mutations were nonfunctional polymorphisms. In contrast, the -83G>C mutation strongly reduced promoter activity. Site-directed mutagenesis of the promoter region revealed the presence of a putative regulatory element (PKR-RE1) whose core binding motif, CTCTG, is located between nt -87 and nt -83. Electrophoretic mobility shift assay using K562 nuclear extracts indicated binding of an as-yet-unidentified trans-acting factor. This novel element mediates the effects of factors necessary for regulation of pyruvate kinase gene expression during red cell differentiation and maturation.

Molecular abnormality of erythrocyte pyruvate kinase deficiency in the Amish

We describe the cellular and molecular biologic studies of the erythrocyte pyruvate kinase (PK) deficiency of the Amish deme in Pennsylvania. Nucleotide sequencing of the patient's PK gene showed a point mutation, CGC to CAC, corresponding to no. 1436 from the translational initiation site of the R-type PK (R-PK) mRNA, and it caused a single amino acid substitution from Arg to His at the 479th amino acid residue of the R-PK. The substituted Arg residue is located in the C domain of PK subunit, that is essential for both the intersubunit contact and the allosteric regulation. Because this enzyme shows the catalytic activity only as a dimer or tetramer, it is rational that the structural alteration would result in severe PK deficiency. To elucidate the effect of the PK deficiency on red blood cell (RBC) membrane, we performed the cellular studies of the patients' RBCs. Ouabain-insensitive K+ efflux was increased to 142% to 145% of normal controls and not inhibited by furosemide, as previously observed in HbSC disease RBCs.

Molecular Abnormality of Erythrocyte Pyruvate Kinase Deficiency in the Amish

Abstract We describe the cellular and molecular biologic studies of the erythrocyte pyruvate kinase (PK) deficiency of the Amish deme in Pennsylvania. Nucleotide sequencing of the patient's PK gene showed a point mutation, CGC to CAC, corresponding to no. 1436 from the translational initiation site of the R-type PK (R-PK) mRNA, and it caused a single amino acid substitution from Arg to His at the 479th amino acid residue of the R-PK. The substituted Arg residue is located in the C domain of PK subunit, that is essential for both the intersubunit contact and the allosteric regulation. Because this enzyme shows the catalytic activity only as a dimer or tetramer, it is rational that the structural alteration would result in severe PK deficiency. To elucidate the effect of the PK deficiency on red blood cell (RBC) membrane, we performed the cellular studies of the patients' RBCs. Ouabain-insensitive K+ efflux was increased to 142% to 145% of normal controls and not inhibited by furosemide, as previously observed in HbSC disease RBCs.

Diagnosis of pyruvate kinase deficiency in a transfusion‐dependent patient with severe hemolytic anemia

In a 2-yr old girl a hemolytic anemia was present since birth requiring multiple blood transfusions. Pyruvate kinase deficiency was suspected on the basis of a marginal enzyme activity, but could not be established due to the presence of massive numbers of donor cells in her peripheral blood. However, by density fractionation we succeeded in the isolation of a small fraction of the patient's own cells, in which a severe pyruvate kinase deficiency could be detected. In contrast hexokinase and glucose-6-phosphate dehydrogenase activities were extremely high, which is indicative that a very immature cell population is present in this fraction. In immunofluorescence studies a clear crossreaction was apparent with anti M2-type pyruvate kinase antibodies, whereas only a faint reaction with anti L-type could be detected. Despite the presence of a slight amount of L-type immunoreactive material, the residual activity in the patient's cell fraction could only be attributed to M2-type pyruvate kinase as was shown by cellulose acetate electrophoresis.

Mathematical modelling of metabolic pathways affected by an enzyme deficiency. A mathematical model of glycolysis in normal and pyruvate-kinase-deficient red blood cells

A mathematical model of glycolysis in human erythrocytes is proposed to study the influence of a pyruvate kinase deficiency on the energy metabolism. The model takes into account the main regulatory properties of the non-equilibrium enzymes and the magnesium-complex formation by the adenine nucleotides and by 2,3-bisphosphoglycerate. In the normal case (no enzyme defect) the calculated flux rates and metabolite concentrations are in a good agreement with experimental data. It is shown that a severe pyruvate kinase deficiency manifested in a tenfold diminished activity of that enzyme leads to a remarkable decrease of the glycolytic flux and the ATP concentration of about 50% of the normal values. On the other hand a lowering of the pyruvate kinase activity to half of the normal value, characteristic for the heterozygotes, gives no significant alterations of the metabolite concentrations and the flux rates compared with the normal case which is in accordance with the lack of clinical symptoms for a metabolic disease of these probands. For three patients with known alterations of their pyruvate kinase mutants the calculated metabolite concentrations and the control characteristics permit estimation of the degree of disorder of the glycolytic pathway. The resulting classification corresponds well to other independent experimental and clinical findings. In particular, the calculation demonstrates that there is no simple correlation between the lowered enzyme activity and the reduced flux rate through the affected pathway.

Red Cell Pyruvate Kinase Deficiency: Adverse Effect of Oral Contraceptives

Erythrocyte enzymopathies are being detected with increasing frequency. The homozygous state for pyruvate kinase (PK) deficiency usually causes chronic non-spherocytic haemolytic anaemia. Aggravation of the condition by a variety of extrinsic factors has been reported, but drugs have rarely been incriminated. A case of severe PK deficiency is presented in which an anovulant drug upsets the usual haematologic balance. This strengthens the suspicion that contraceptive pills may be hazardous in such patients.