Liver cirrhosis as a consequence of iron overload caused by hereditary nonspherocytic hemolytic anemia

Acute-on-Chronic Liver Failure and Successful Liver Transplantation in Pyruvate Kinase Deficiency

Liver transplant is a rare phenomenon for pyruvate kinase deficiency (PKD)-related liver disease and can be mediated by multiple mechanisms. In this report, we present a 55-year-old man with PKD who had acute-on-chronic liver failure with kidney failure and marked hyperbilirubinemia. His liver disease was from recurrent cholangitis, cholestasis from hemolysis, and iron deposition (likely from both repeated transfusions in youth and chronic hemolysis), all consequences of his PKD. He received a liver transplant and had a good outcome. Our case highlights the mechanisms of liver injury in PKD and successful transplantation for this rare complication.

Iron deficiency in cardiac surgical patients

Iron is an essential element and involved in a variety of metabolic processes including oxygen transport, cellular energy production, energy metabolism of heart muscles, brain function, cell growth and cell differentiation. Preoperative anaemia is an independent risk factor for poor outcome. Recently, iron deficiency was considered only in the context of anaemia. However, negative consequences of iron deficiency in the absence of anaemia have been described for patients undergoing cardiac surgery. To date, the benefit of intravenous iron supplementation in these patients has been controversially debated. In this review, we discuss the latest progress in studies of intravenous iron supplementation in iron deficient cardiac surgical patients.

Dual-Energy Computed Tomography in Diffuse Liver Diseases

Dual-energy computed tomography (DECT) is an advancement in the field of CT, where images are acquired at two energies. Materials are identified and quantified based on their attenuation pattern at two different energy beams using various material decomposition algorithms. With its ability to identify and quantify materials such as fat, calcium, iron, and iodine, DECT adds great value to conventional CT and has innumerable applications in body imaging. Continuous technological advances in CT scanner hardware, material decomposition algorithms, and image reconstruction software have led to considerable growth of these applications. Among all organs, the liver is the most widely investigated by DECT, and DECT has shown promising results in most liver applications. In this article, we aim to provide an overview of the role of DECT in the assessment of diffuse liver diseases, mainly the deposition of fat, fibrosis, and iron and review the most relevant literature.

Successful Liver Transplantation for Adolescent Patient With Pyruvate Kinase Deficiency-induced Cirrhosis

We present the case of a successful liver transplant in a young adult patient with cholestasis and cirrhosis secondary to severe pyruvate kinase (PK) deficiency. Liver transplant resulted in resolution of liver dysfunction, decreased need for blood transfusions and eligibility for bone marrow transplantation. This case represents the third reported patient in the literature with severe PK deficiency who successfully underwent liver transplant as a result of profound cholestasis and liver failure. Explant pathology demonstrated a lack of significant iron deposition indicating that PK deficiency predisposes the liver to injury independent of transfusion-related iron overload.

Appraisal of patient-reported outcome measures in analogous diseases and recommendations for use in phase II and III clinical trials of pyruvate kinase deficiency

PURPOSE

Pyruvate kinase deficiency (PKD) is a rare disease and understanding of its epidemiology and associated burden remains limited. With no current curative therapy, clinical manifestations can be life threatening, clinically managed by maintaining adequate hemoglobin levels through transfusion and subsequent support, but with frequent complications. Treatment goals are to maintain/improve the patient's quality of life. With new therapies, reliable, valid, and relevant patient-reported outcome (PRO) tools are required for use in clinical trials.

METHODS

Systematic literature search identified no current PRO tools for capturing/measuring the impact of PKD and treatments in clinical trials. Therefore, the search strategy was revised to consider conditions analogous to PKD in terms of symptoms and impacts that might serve as parallels to the experience in PKD; this included sickle cell anemia, thalassemia, and hemolytic anemia. Psychometric properties, strengths, and weakness of selected appropriate PRO instruments were compared, and recommendations made for choice of PRO tools.

RESULTS

In adult populations, EORTC QLQ C30 and SF-36v2 are recommended, the former being a basic minimum, covering generic HRQoL, and core symptoms such as fatigue. In pediatric populations, PedsQL Generic Core Scale to measure HRQoL and PedsQL MFS scale to measure fatigue are recommended.

CONCLUSIONS

Some symptoms/life impacts may be unique to PKD and not observable in analogous conditions. A 'Physico-Psychosocial Model' derived from the 'Medical Model' is proposed to form the basis for a hypothesized conceptual framework to address the development of PKD-specific PRO instruments.

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.

Blockade of mitochondrial calcium uniporter prevents cardiac mitochondrial dysfunction caused by iron overload

AIM

Iron overload in the heart can lead to iron-overload cardiomyopathy and cardiac arrhythmia. In the past decades, growing evidence has suggested that cardiac mitochondrial dysfunction is associated with the development of cardiac dysfunction and lethal arrhythmias. Despite these facts, the effect of iron overload on cardiac mitochondrial function is still unclear. In this study, we determined the effects of iron overload on the cardiac mitochondrial function and the routes of cardiac mitochondrial iron uptake. We tested the hypothesis that iron overload can lead to cardiac mitochondrial dysfunction and that mitochondrial calcium uniporter (MCU) plays a major role for cardiac mitochondrial iron uptake under iron-overload condition. Cardiac mitochondrial function was assessed via the determination of mitochondrial swelling, mitochondrial reactive oxygen species (ROS) production and mitochondrial membrane potential changes.

METHODS

Isolated cardiac mitochondria from male Wistar rats were used in this study. To determine the routes for cardiac mitochondrial iron uptake, isolated mitochondria were exposed to MCU blocker (Ru360), mitochondrial permeability transition pore (mPTP) blocker (cyclosporin A) and an iron chelator (deferoxamine).

RESULTS

We found that (i) iron overload caused cardiac mitochondrial dysfunction, indicated by increased ROS production, mitochondrial membrane depolarization and mitochondrial swelling; and (ii) only MCU blocker completely protected cardiac mitochondrial dysfunction caused by iron overload.

CONCLUSIONS

These findings strongly suggest that MCU could be the major route for iron uptake into cardiac mitochondria. The inhibition of MCU could be the novel pharmacological intervention for preventing iron-overload cardiomyopathy.

Erythrocyte pyruvate kinase deficiency in an old-order Amish cohort: longitudinal risk and disease management

Pyruvate kinase deficiency is a chronic illness with age specific consequences. Newborns suffer life-threatening hemolytic crisis and hyperbilirubinemia. Adults are at risk for infections because of asplenia, pregnancy-related morbidity, and may suffer organ damage because of systemic iron overload. We describe 27 Old Order Amish patients (ages 8 months-52 years) homozygous for c.1436G>A mutations in PKLR. Each subject had a predictable neonatal course requiring packed red blood cell transfusions (30 ± 5 mL/kg) to control hemolytic disease and intensive phototherapy to prevent kernicterus. Hemochromatosis affected 29% (n = 4) of adult patients, who had inappropriately normal serum hepcidin (34.5 ± 12.7 ng/mL) and GDF-15 (595 ± 335pg/mL) relative to hyperferritinemia (769 ± 595 mg/dL). A high prevalence of HFE gene mutations exists in this population and may contribute to iron-related morbidity. Based on our observations, we present a strategy for long-term management of pyruvate kinase deficiency.

Bilirubin cholelithiasis and haemosiderosis in an anaemic pyruvate kinase-deficient Somali cat

A Somali cat was presented with recurrent anorexia, lethargy, vomiting and icterus. A macrocytic-hypochromic, regenerative haemolytic anaemia was identified and hereditary pyruvate kinase deficiency was confirmed by means of breed-specific DNA mutation analysis. The case was complicated by the presence of markedly elevated serum liver enzyme activities, hyperbilirubinaemia, coagulopathy and ultrasonographic evidence of gall bladder choleliths and extrahepatic bile duct obstruction. The choleliths consisted of 100 per cent bilirubin, likely because of chronic haemolysis and haeme degradation. In conclusion, haemosiderosis and bilirubin cholelithiasis can be a consequence of chronic haemolysis in pyruvate kinase-deficient cats, as seen in human beings with a variety of chronic haemolytic disorders.

Clinical course of pyruvate kinase deficiency in Abyssinian and Somali cats

The objective of this study was to examine clinical signs, laboratory parameters, and course of disease in Abyssinian and Somali cats with pyruvate kinase (PK) deficiency. The clinical course of 25 PK-deficient cats was followed over a time period of 0.8-11.3 years (median 4.3). Eleven cats (age 0.8-7.8 years, median 4.4) did not show signs according to the owners. In 14 cats (age 0.1-5 years, median 1.7) the owners noted lethargy (10), diarrhoea (seven), pale mucous membranes (six), inappetence (six), poor coat quality (six), weight loss (four), icterus (four), and pica (two). Sixteen cats had been used for breeding at least once before diagnosis. Laboratory abnormalities included anaemia (70%), increased aggregated reticulocyte counts (94%), hyperglobulinaemia (80%), hyperbilirubinaemia (53%), and increased liver enzymes (47%). Six of 25 affected cats died (four) or were euthanased (two) at ages ranging from 1.3 to 11.3 years (median 4.1) presumably because of PK-deficiency. These findings emphasise that PK deficiency shows variation in age of onset and severity of signs. As PK-deficient cats can be asymptomatic testing for PK deficiency before breeding is strongly recommended.

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.

Pyruvate kinase deficiency: the genotype-phenotype association

Red cell pyruvate kinase (PK) deficiency is the most frequent enzyme abnormality of glycolysis causing chronic non-spherocytic haemolytic anaemia. The disease is transmitted as an autosomal recessive trait, clinical symptoms usually occurring in compound heterozygotes for two mutant alleles and in homozygotes. The severity of haemolysis is highly variable, ranging from very mild or fully compensated forms to life-threatening neonatal anaemia necessitating exchange transfusions. Erythrocyte PK is synthesised under the control of the PK-LR gene located on chromosome 1. One hundred eighty different mutations in PK-LR gene, mostly missense, have been so far reported associated to PK deficiency. First attempts to delineate the genotype-phenotype association were mainly based on the analysis of the enzyme's three-dimensional structure and the observation of the few homozygous patients. More recently, the comparison of the recombinant mutants of human red cell PK with the wild-type enzyme has enabled the effects of amino acid replacements on the enzyme molecular properties to be determined. However, the clinical manifestations of red cell enzyme defects are not merely dependent on the molecular properties of the mutant protein but rather reflect the complex interactions of additional factors, including genetic background, concomitant functional polymorphisms of other enzymes, posttranslational or epigenetic modifications, ineffective erythropoiesis and differences in splenic function.

Disparate phenotypic expression of ALAS2 R452H (nt 1407 G → A) in two brothers, one with severe sideroblastic anemia and iron overload, hepatic cirrhosis, and hepatocellular carcinoma

We report the case of a man with severe X-linked sideroblastic anemia, severe iron overload, and hepatic cirrhosis who died of hepatocellular carcinoma. Evaluation of family members using DNA sequencing revealed that he was hemizygous for the novel ALAS2 mutation R452H (exon 9; nt 1407 G --> A). The proband's brother, an ALAS2 R452H hemizygote, had mild anemia and mild iron overload. Four female relatives were ALAS2 R452H heterozygotes, but they had mild or no anemia and no iron overload. Sequencing of TFR2, HFE, FPN1 (SLC40A1), HAMP, HJV, and the erythrocyte pyruvate kinase genes of family members was also performed. We thus detected the novel TFR2 missense mutation I449V (exon 10; nt 1345 A --> G) in the proband's wife and daughter, neither of whom had anemia or iron overload. Possible explanations for the disparate red blood cell and iron phenotypes of the proband and his family members are discussed.