Diagnosis, monitoring, and management of pyruvate kinase deficiency in children.

Pyruvate kinase (PK) deficiency is a rare, congenital red blood cell disorder caused by a single gene defect. The spectrum of genotypes, variants, and phenotypes are broad, commonly requiring a multimodal approach including enzyme and genetic testing for accurate and reliable diagnosis. Similarly, management of primary and secondary sequelae of PK deficiency varies, mainly including supportive care with transfusions and surgical interventions to improve symptoms and quality of life. Given the risk of acute and long-term complications of PK deficiency and its treatment, regular monitoring and management of iron burden and organ dysfunction is critical. Therefore, all children and adolescents with PK deficiency should receive regular hematology care with visits at least every 6 months regardless of transfusion status. We continue to learn more about the spectrum of symptoms and complications of PK deficiency and best practice for monitoring and management through registry efforts (NCT03481738). The treatment of PK deficiency has made strides over the last few years with newer disease-modifying therapies being developed and studied, with the potential to change the course of disease in childhood and beyond.

A pyruvate kinase deficiency child with novel PK-LR gene mutations was successfully cured by matched unrelated donor peripheral blood stem cell transplantation.

BACKGROUND: Pyruvate kinase deficiency (PKD) is an autosomal recessive disorder caused by a PK-LR gene mutation. Allogeneic hematopoietic cell transplantation (HCT) is an effective cure for PKD. However, the experience of applying HCT in PKD is limited. METHODS: We present a child with novel PK-LR gene mutations who was successfully cured by matched unrelated donor peripheral blood stem cell transplantation (MUD-PBSCT). RESULTS: A 4-year-old, male patient suffered severe hemolytic anemia and jaundice 5 h after birth. Gene sequencing showed that the pyruvate kinase-liver and RBC (PK-LR) gene had a nonsense mutation in exon 5: c.602G>A (p.W201X), and large deletions in exons 3-9. Both of them were novel pathogenic mutations of the PK-LR gene. After transplantation, the hemoglobin level became normal and the nonsense mutation was undetectable. Grade Ⅳ acute graft-versus-host disease (aGVHD) and extensive chronic graft-versus-host disease (cGVHD) occurred in the patient. However, the GVHD was controlled effectively. The patient is alive and has good quality of life 22 months post-transplant, but has mild oral lichen planus-like lesion. CONCLUSION: Gene sequencing contributes to the diagnosis of PKD. HCT is an effective method for curing PKD, but we should explore how to reduce severe GVHD.

Pyruvate kinase deficiency in children.

BACKGROUND: Pyruvate kinase deficiency (PKD) is a rare, autosomal recessive red blood cell enzyme disorder, which leads to lifelong hemolytic anemia and associated complications from the disease and its management. METHODS: An international, multicenter registry enrolled 124 individuals younger than 18 years old with molecularly confirmed PKD from 29 centers. Retrospective and prospective clinical data were collected. RESULTS: There was a wide range in the age at diagnosis from 0 to 16 years. Presentation in the newborn period ranged from asymptomatic to neonatal jaundice to fulminant presentations of fetal distress, myocardial depression, and/or liver failure. Children <5 years old were significantly more likely to be transfused than children >12 to <18 years (53% vs. 14%, p = .0006), which correlated with the timing of splenectomy. Regular transfusions were most common in children with two severe PKLR variants. In regularly transfused children, the nadir hemoglobin goal varied considerably. Impact on quality of life was a common reason for treatment with regular blood transfusions and splenectomy. Splenectomy increased the hemoglobin and decreased transfusion burden in most children but was associated with infection or sepsis (12%) and thrombosis (1.3%) even during childhood. Complication rates were high, including iron overload (48%), perinatal complications (31%), and gallstones (20%). CONCLUSIONS: There is a high burden of disease in children with PKD, with wide practice variation in monitoring and treatment. Clinicians must recognize the spectrum of the manifestations of PKD for early diagnostic testing, close monitoring, and management to avoid serious complications in childhood.

[Consensus document for the diagnosis and treatment of pyruvate kinase deficiency]. / Documento de consenso para el diagnóstico y tratamiento del déficit de piruvato quinasa.

Pyruvate kinase (PK) deficiency is the second most frequent enzymopathy and the most common cause of chronic hereditary non-spherocytic haemolytic anaemia. Its global prevalence is underestimated due to low clinical suspicion of mild cases, associated with difficulties in the performance and interpretation of PK enzymatic activity assays. With the advent of next generation sequencing techniques, a better diagnostic approach is achieved. Treatment remains based on red blood cell transfusions and splenectomy, with special attention to iron overload, not only in transfusion-dependent patients. Nowadays, allogeneic hematopoietic stem cell transplantation is the only curative treatment, recommended only in selected cases of severely affected patients with an HLA-identical donor. Novel pharmacological and gene therapies are in clinical trials, with promising results. In this article, the Spanish Erythropathology Group reviews the current situation of PK deficiency, paying special attention to the usefulness of different diagnostic techniques and to actual and emerging treatments.

Management of pyruvate kinase deficiency in children and adults.

Pyruvate kinase deficiency (PKD) is an autosomal-recessive enzyme defect of the glycolytic pathway that causes congenital nonspherocytic hemolytic anemia. The diagnosis and management of patients with PKD can be challenging due to difficulties in the diagnostic evaluation and the heterogeneity of clinical manifestations, ranging from fetal hydrops and symptomatic anemia requiring lifelong transfusions to fully compensated hemolysis. Current treatment approaches are supportive and include transfusions, splenectomy, and chelation. Complications, including iron overload, bilirubin gallstones, extramedullary hematopoiesis, pulmonary hypertension, and thrombosis, are related to the chronic hemolytic anemia and its current management and can occur at any age. Disease-modifying therapies in clinical development may decrease symptoms and findings associated with chronic hemolysis and avoid the complications associated with current treatment approaches. As these disease-directed therapies are approved for clinical use, clinicians will need to define the types of symptoms and findings that determine the optimal patients and timing for initiating these therapies. In this article, we highlight disease manifestations, monitoring approaches, strategies for managing complications, and novel therapies in development.

Safe and Efficient Gene Therapy for Pyruvate Kinase Deficiency.

Pyruvate kinase deficiency (PKD) is a monogenic metabolic disease caused by mutations in the PKLR gene that leads to hemolytic anemia of variable symptomatology and that can be fatal during the neonatal period. PKD recessive inheritance trait and its curative treatment by allogeneic bone marrow transplantation provide an ideal scenario for developing gene therapy approaches. Here, we provide a preclinical gene therapy for PKD based on a lentiviral vector harboring the hPGK eukaryotic promoter that drives the expression of the PKLR cDNA. This therapeutic vector was used to transduce mouse PKD hematopoietic stem cells (HSCs) that were subsequently transplanted into myeloablated PKD mice. Ectopic RPK expression normalized the erythroid compartment correcting the hematological phenotype and reverting organ pathology. Metabolomic studies demonstrated functional correction of the glycolytic pathway in RBCs derived from genetically corrected PKD HSCs, with no metabolic disturbances in leukocytes. The analysis of the lentiviral insertion sites in the genome of transplanted hematopoietic cells demonstrated no evidence of genotoxicity in any of the transplanted animals. Overall, our results underscore the therapeutic potential of the hPGK-coRPK lentiviral vector and provide high expectations toward the gene therapy of PKD and other erythroid metabolic genetic disorders.

Two Novel Missense Mutations and a 5bp Deletion in the Erythroid-Specific Promoter of the PKLR Gene in Two Unrelated Patients With Pyruvate Kinase Deficient Transfusion-Dependent Chronic Nonspherocytic Hemolytic Anemia.

We report two children with severe chronic hemolytic anemia, the cause of which was difficult to establish because of transfusion dependency. Reduced erythrocyte pyruvate kinase activity in their asymptomatic parents provided the diagnostic clues for mutation screening of the PKLR gene and revealed that one child was a compound heterozygote of a novel paternally derived 5-bp deletion in the promoter region (c.-88_-84delTCTCT) and a maternally derived missense mutation in exon nine (c.1174G>A; p.Ala392Thr). The second child was a compound heterozygote of two novel missense mutations, namely a paternally derived exon ten c.1381G>A (p.Glu461Lys) and a maternally derived exon seven c.907-908delCC (p.Pro303GlyfsX12) variant.

Stem cell selection in vivo using foamy vectors cures canine pyruvate kinase deficiency.

BACKGROUND: Hematopoietic stem cell (HSC) gene therapy has cured immunodeficiencies including X-linked severe combined immunodeficiency (SCID-X1) and adenine deaminase deficiency (ADA). For these immunodeficiencies corrected cells have a selective advantage in vivo, and low numbers of gene-modified cells are sufficient to provide therapeutic benefit. Strategies to efficiently transduce and/or expand long-term repopulating cells in vivo are needed for treatment of diseases that require higher levels of corrected cells, such as hemoglobinopathies. Here we expanded corrected stem cells in vivo in a canine model of a severe erythroid disease, pyruvate kinase deficiency. METHODOLOGY/PRINCIPAL FINDINGS: We used a foamy virus (FV) vector expressing the P140K mutant of methylguanine methyltransferase (MGMTP140K) for in vivo expansion of corrected hematopoietic repopulating cells. FV vectors are attractive gene transfer vectors for hematopoietic stem cell gene therapy since they efficiently transduce repopulating cells and may be safer than more commonly used gammaretroviral vectors. Following transplantation with HSCs transduced ex vivo using a tri-cistronic FV vector that expressed EGFP, R-type pyruvate kinase, and MGMTP140K, we were able to increase marking from approximately 3.5% to 33% in myeloid long-term repopulating cells resulting in a functional cure. CONCLUSIONS/SIGNIFICANCE: Here we describe in one affected dog a functional cure for a severe erythroid disease using stem cell selection in vivo. In addition to providing a potential cure for patients with pyruvate kinase deficiency, in vivo selection using foamy vectors with MGMTP140K has broad potential for several hematopoietic diseases including hemoglobinopathies.