Pyruvate kinase deficiency as a cause of extreme hyperbilirubinemia in neonates from a polygamist community

Rare liver diseases in Egypt: Clinical and epidemiological characterization

Illnesses that afflict a tiny number of individuals are referred to as rare diseases (RDs), sometimes called orphan diseases. The local healthcare systems are constantly under financial, psychological, and medical strain due to low incidence rates, unusual presentations, flawed diagnostic standards, and a lack of treatment alternatives for these RDs. The effective management of the once widely spread viral hepatitis B and C has altered the spectrum of liver diseases in Egypt during the last several years. The detection of uncommon disorders such as autoimmune, cholestatic, and hereditary liver diseases has also been made easier by the increasing knowledge and greater accessibility of specific laboratory testing. Finally, despite Egypt's large population, there are more uncommon liver disorders than previously thought. This review article discusses the clinical and epidemiological characteristics of a few uncommon liver disorders and the information currently accessible concerning these illnesses in Egypt.

Clinical outcome and genotype analysis of four Chinese children with pyruvate kinase deficiency

BACKGROUND

Pyruvate kinase deficiency (PKD) is a rare congenital hemolytic anemia. Here, we summarized the clinical features and laboratory examinations of four Chinese children with PKD and analyze genomic mutations.

METHOD

Collected and analyzed the clinical data of all children and their parents and completed the relevant laboratory examinations of all children. Analyzed the sequences of related genes in children by second-generation sequencing technology and verified the suspected mutations in children's family by Sanger sequencing method or second-generation sequencing technology.

RESULTS

A total of six mutations in gene PKLR were detected in four cases. Except for c.1510C>T (P1) and c.941T>C (P2 and P4), which had been reported in previous studies, the other four novel gene mutations were reported for the first time, including a rare homozygous mutation with large fragment deletion. All those gene mutations cause changes in the amino acids encoded by the gene, as well as subsequent changes in protein structure or loss of function.

CONCLUSION

Compound heterozygous or homozygous mutations in the coding region of PKLR gene are the causes of PKD in these four Chinese children. The second-generation sequencing technology is an effective means to diagnose PKD. The mutations of c.457-c.462delATCGCC, c.1297T>C, c.1096C>T and Exon4-10del of PKLR reported in this article have not been included in the Thousand Genome Database, dbSNP(v138) and ExAC Database. The PKLR gene mutations found in these children with PKD can provide references for further research of the genetic characteristics of PKD and subsequent gene therapy.

Specific correction of pyruvate kinase deficiency-causing point mutations by CRISPR/Cas9 and single-stranded oligodeoxynucleotides

Pyruvate kinase deficiency (PKD) is an autosomal recessive disorder caused by mutations in the PKLR gene. PKD-erythroid cells suffer from an energy imbalance caused by a reduction of erythroid pyruvate kinase (RPK) enzyme activity. PKD is associated with reticulocytosis, splenomegaly and iron overload, and may be life-threatening in severely affected patients. More than 300 disease-causing mutations have been identified as causing PKD. Most mutations are missense mutations, commonly present as compound heterozygous. Therefore, specific correction of these point mutations might be a promising therapy for the treatment of PKD patients. We have explored the potential of precise gene editing for the correction of different PKD-causing mutations, using a combination of single-stranded oligodeoxynucleotides (ssODN) with the CRISPR/Cas9 system. We have designed guide RNAs (gRNAs) and single-strand donor templates to target four different PKD-causing mutations in immortalized patient-derived lymphoblastic cell lines, and we have detected the precise correction in three of these mutations. The frequency of the precise gene editing is variable, while the presence of additional insertions/deletions (InDels) has also been detected. Significantly, we have identified high mutation-specificity for two of the PKD-causing mutations. Our results demonstrate the feasibility of a highly personalized gene-editing therapy to treat point mutations in cells derived from PKD patients.

Clinically relevant gene editing in hematopoietic stem cells for the treatment of pyruvate kinase deficiency

Pyruvate kinase deficiency (PKD), an autosomal-recessive disorder, is the main cause of chronic non-spherocytic hemolytic anemia. PKD is caused by mutations in the pyruvate kinase, liver and red blood cell (PKLR) gene, which encodes for the erythroid pyruvate kinase protein (RPK). RPK is implicated in the last step of anaerobic glycolysis in red blood cells (RBCs), responsible for the maintenance of normal erythrocyte ATP levels. The only curative treatment for PKD is allogeneic hematopoietic stem and progenitor cell (HSPC) transplant, associated with a significant morbidity and mortality, especially relevant in PKD patients. Here, we address the correction of PKD through precise gene editing at the PKLR endogenous locus to keep the tight regulation of RPK enzyme during erythropoiesis. We combined CRISPR-Cas9 system and donor recombinant adeno-associated vector (rAAV) delivery to build an efficient, safe, and clinically applicable system to knock in therapeutic sequences at the translation start site of the RPK isoform in human hematopoietic progenitors. Edited human hematopoietic progenitors efficiently reconstituted human hematopoiesis in primary and secondary immunodeficient mice. Erythroid cells derived from edited PKD-HSPCs recovered normal ATP levels, demonstrating the restoration of RPK function in PKD erythropoiesis after gene editing. Our gene-editing strategy may represent a lifelong therapy to correct RPK functionality in RBCs for PKD patients.

Severe Presentation of Congenital Hemolytic Anemias in the Neonatal Age: Diagnostic and Therapeutic Issues

Congenital hemolytic anemias (CHAs) are a group of diseases characterized by premature destruction of erythrocytes as a consequence of intrinsic red blood cells abnormalities. Suggestive features of CHAs are anemia and hemolysis, with high reticulocyte count, unconjugated hyperbilirubinemia, increased lactate dehydrogenase (LDH), and reduced haptoglobin. The peripheral blood smear can help the differential diagnosis. In this review, we discuss the clinical management of severe CHAs presenting early on in the neonatal period. Appropriate knowledge and a high index of suspicion are crucial for a timely differential diagnosis and management. Here, we provide an overview of the most common conditions, such as glucose-6-phosphate dehydrogenase deficiency, pyruvate kinase deficiency, and hereditary spherocytosis. Although rare, congenital dyserythropoietic anemias are included as they may be suspected in early life, while hemoglobinopathies will not be discussed, as they usually manifest at a later age, when fetal hemoglobin (HbF) is replaced by the adult form (HbA).

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.

Comorbidities and complications in adults with pyruvate kinase deficiency

Objectives

Pyruvate kinase (PK) deficiency is caused by PKLR gene mutations, leading to defective red blood cell glycolysis and hemolytic anemia. Rates of comorbidities and complications by transfusion history and relative to the general population remain poorly quantified.

Methods

Data for patients aged ≥ 18 years with two confirmed PKLR mutations were obtained from the PK deficiency Natural History Study (NCT02053480). Frequencies of select conditions were compared with an age‐ and sex‐matched cohort from a general insured US population without PK deficiency.

Results

Compared with the matched population (n = 1220), patients with PK deficiency (n = 122) had significantly higher lifetime rates of osteoporosis, liver cirrhosis, and pulmonary hypertension; splenectomy and cholecystectomy rates were also significantly higher in the 8 years before the index date. Sixty‐five (53.3%) patients with PK deficiency were classified as regularly transfused, 30 (24.6%) as occasionally transfused, and 27 (22.1%) as never transfused. Regularly transfused patients were significantly more likely than never transfused patients to have had splenectomy, cholecystectomy, and/or thrombosis. Liver iron overload was reported in 62% of patients and occurred regardless of transfusion cohort.

Conclusions

Even never transfused patients with PK deficiency had higher rates of select comorbidities and complications than individuals without PK deficiency.

Prevalence of pyruvate kinase deficiency: A systematic literature review

OBJECTIVES

Pyruvate kinase deficiency (PK deficiency) is a rare disorder caused by compound heterozygosity or homozygosity for > 300 mutations in the PKLR gene. To understand PK deficiency prevalence, we conducted a systematic literature review.

METHODS

We queried Embase and Medline for peer-reviewed references reporting PK deficiency prevalence/incidence, PKLR mutant allele frequency (MAF) among the general population, or crude results from which these metrics could be derived.

RESULTS

Of 1390 references screened, 1296 were excluded after title/abstract review; 60 were excluded after full-text review. Four of the remaining 34 studies were considered high-quality for estimating PK deficiency prevalence. Two high-quality studies identified cases from source populations of known sizes, producing estimates of diagnosed PK deficiency prevalence of 3.2 and 8.5 per million. Another high-quality study derived an estimate of diagnosed PK deficiency prevalence of 6.5 per million by screening jaundiced newborns. The final high-quality study estimated total diagnosed and undiagnosed PK deficiency prevalence to be 51 per million through extrapolation from observed MAFs.

CONCLUSIONS

We conclude that prevalence of clinically diagnosed PK deficiency is likely between 3.2 and 8.5 per million in Western populations, while the prevalence of diagnosed and undiagnosed PK deficiency could possibly be as high as 51 per million.

Addressing the diagnostic gaps in pyruvate kinase deficiency: Consensus recommendations on the diagnosis of pyruvate kinase deficiency

Pyruvate kinase deficiency (PKD) is the most common enzyme defect of glycolysis and an important cause of hereditary, nonspherocytic hemolytic anemia. The disease has a worldwide geographical distribution but there are no verified data regarding its frequency. Difficulties in the diagnostic workflow and interpretation of PK enzyme assay likely play a role. By the creation of a global PKD International Working Group in 2016, involving 24 experts from 20 Centers of Expertise we studied the current gaps in the diagnosis of PKD in order to establish diagnostic guidelines. By means of a detailed survey and subsequent discussions, multiple aspects of the diagnosis of PKD were evaluated and discussed by members of Expert Centers from Europe, USA, and Asia directly involved in diagnosis. Broad consensus was reached among the Centers on many clinical and technical aspects of the diagnosis of PKD. The results of this study are here presented as recommendations for the diagnosis of PKD and used to prepare a diagnostic algorithm. This information might be helpful for other Centers to deliver timely and appropriate diagnosis and to increase awareness in PKD.

Phase 1 Single- and Multiple-Ascending-Dose Randomized Studies of the Safety, Pharmacokinetics, and Pharmacodynamics of AG-348, a First-in-Class Allosteric Activator of Pyruvate Kinase R, in Healthy Volunteers

Pyruvate kinase deficiency is a chronic hemolytic anemia caused by mutations in PK-R, a key glycolytic enzyme in erythrocytes. These 2 phase 1 randomized, placebo-controlled, double-blind healthy-volunteer studies assessed the safety, tolerability, and pharmacokinetics/pharmacodynamics of AG-348, a first-in-class allosteric PK-R activator. Twelve sequential cohorts were randomized 2:6 to receive oral placebo or AG-348, respectively, as a single dose (30-2500 mg) in the single-ascending-dose (SAD) study (ClinicalTrials.gov: NCT02108106) or 15-700 mg every 12 hours or 120 mg every 24 hours, for 14 days in the multiple-ascending-dose (MAD) study (ClinicalTrials.gov: NCT02149966). All 48 subjects completed the fasted SAD part; 44 of 48 completed the MAD (2 discontinued because of adverse events [AEs], 2 withdrew consent). The most common treatment-related AEs in AG-348-treated subjects were headache (16.7% [SAD] and 13.9% [MAD]) and nausea (13.9%, both studies). AE frequency increased at AG-348 doses ≥ 700 mg (SAD) and at 700 mg every 12 hours (MAD); 1 grade ≥ 3 AE occurred in the latter cohort. Pharmacokinetics were favorable with low variability. Dose-dependent changes in blood glycolytic intermediates consistent with glycolytic pathway activation were observed at all MAD doses, supporting future trials investigating the potential of AG-348 for treating PK deficiency or other anemias.

Congenital thrombotic thrombocytopenic purpura: Upshaw-Schulman syndrome: a cause of neonatal death and review of literature

Thrombotic thrombocytopenic purpura (TTP) is a rare disorder in children characterized by microangiopathic hemolytic anemia (MAHA) and thrombocytopenia. The classic Moschcowitz Pentads of TTP include hemolytic anemia, with fragmentation of erythrocytes, thrombocytopenia, diffuse and non-focal neurologic findings, decrease renal function and fever. We report a newborn who was diagnosed with congenital TTP. The newborn was admitted at age of 40 h, in our hospital, in view of respiratory distress with impending respiratory failure and red colored urine. On examination, the newborn was febrile, tachypneic, had deep icterus, pallor and no hepatosplenomegaly. Family history was significant with one unexplained neonatal death at age of 24 with symptoms of red colored urine. Examination of peripheral smear was diagnostic with the presence of fragmented RBCS, giant but fewer platelets consistent with a diagnosis of MAHA. The diagnosis of TTP was confirmed with low ADAMTS activity and gene analysis showed c 2203 G > T-p.Glu735X (domain TSP1-2) mutation in exon 18 of ADAMTS 13 gene. The newborn had rapid deterioration, with respiratory distress and refractory shock leading to death. Post-mortem bone marrow done showed marrow hyperplasia.

Common hematologic problems in the newborn nursery

"Common red blood cell disorders encountered in the normal newborn nursery include hemolytic disease of the newborn and resultant hyperbilirubinemia, anemia, and polycythemia. A less frequent clinically relevant hematologic issue in newborns to be covered herein is thrombocytopenia."

Health beliefs and practices in an isolated polygamist community of southern Utah

Short Creek is a largely closed and isolated community on the border between Utah and Arizona, made up of the sister towns of Hildale, Utah, and Colorado City, Arizona. Beginning from childhood, the 6,000 or so members of the Fundamentalist Church of Jesus Christ of Latter-Day Saints (FLDS) are brought up in a lifestyle of plural marriage, meaning a marriage among one man and more than one woman, and are surrounded by their peers in "the covenant." A lifestyle of plural marriage is likely to affect the health of community members, but its effects have not been studied because of the community's isolation and distrust of outsiders. This paper addresses several questions that arise in contemplating the health of the Short Creek community: What are the health beliefs in this community, and what are their historical bases? Where do families seek medical care, and for what or at what threshold of illness or injury? What is the attitude of care providers serving this community, and how are the providers viewed by the community? More broadly, this paper examines the ways in which polygamy configures health. In order to meet this objective, this paper aims first to provide a brief account of this community's history and demographic profile, followed by a discussion of health care in this community and how it is affected by the practice of plural marriage, with the data comprised of qualitative interviews with health care providers to the community. The goals of this project are to gain a rich, historically nuanced understanding of the health of community members, and to identify directions for further academic and policy research. Our findings indicate that health in this community is shaped by limited resources, an attitude of health fatalism, and a profound insularity and corresponding isolation from the outside world.

Unexplained extreme hyperbilirubinemia among neonates in a multihospital healthcare system

We report a series of neonates who developed a total serum bilirubin (TSB) >20mg/dL during a recent ten-year period in a multihospital healthcare system. The incidence of a TSB >20mg/dL fell after instituting a pre-hospital discharge bilirubin screening program in 2003/2004 (91.3 cases/10,000 births before vs. 72.4/10,000 after), but the incidence has subsequently remained unchanged. No specific cause for the hyperbilirubinemia was identified in 66% of (n=32) cases with a TSB >30 mg/dL or in 76% of (n=112) cases with a TSB 25.0-29.9 mg/dL. We hypothesized that hemolysis was a common contributing mechanism, but our review of hospital records indicated that in most instances these infants were not evaluated sufficiently to test this hypothesis. Records review showed maternal and neonatal blood types and direct antiglobulin testing were performed in >95% cases, but rarely were other tests for hemolysis obtained. In the ten-year period reviewed there were zero instances where erythrocyte morphology from a blood film examination or Heinz body evaluation by a pediatric hematologist or pathologist were performed. In 3% of cases pyruvate kinase was tested, 3% were evaluated by hemoglobin electrophoresis, 3% had a haptoglobin measurement, and 16% were tested for G6PD deficiency. Thus, determining the cause for hyperbilirubinemia in neonates remains a problem at Intermountain Healthcare and, we submit, elsewhere. As a result, the majority of infants with a TSB >25mg/dL have no specific causation identified. We speculate that most of these cases involve hemolysis and that the etiology could be identified if searched for more systematically. With this in mind, we propose a "consistent approach" to evaluating the cause(s) of hyperbilirubinemia among neonates with a TSB >25mg/dL.

Erythrocytic pyruvate kinase mutations causing hemolytic anemia, osteosclerosis, and secondary hemochromatosis in dogs

BACKGROUND

Erythrocytic pyruvate kinase (PK) deficiency, first documented in Basenjis, is the most common inherited erythroenzymopathy in dogs.

OBJECTIVES

To report 3 new breed-specific PK-LR gene mutations and a retrospective survey of PK mutations in as mall and selected group of Beagles and West Highland White Terriers (WHWT).

ANIMALS

Labrador Retrievers (2 siblings, 5 unrelated), Pugs (2 siblings, 1 unrelated), Beagles (39 anemic, 29 other),WHWTs (22 anemic, 226 nonanemic), Cairn Terrier (n = 1).

METHODS

Exons of the PK-LR gene were sequenced from genomic DNA of young dogs (<2 years) with persistent highly regenerative hemolytic anemia.

RESULTS

A nonsense mutation (c.799C>T) resulting in a premature stop codon was identified in anemic Labrador Retriever siblings that had osteosclerosis, high serum ferritin concentrations, and severe hepatic secondary hemochromatosis. Anemic Pug and Beagle revealed 2 different missense mutations (c.848T>C, c.994G>A, respectively) resulting in intolerable amino acid changes to protein structure and enzyme function. Breed-specific mutation tests were developed. Among the biased group of 248 WHWTs, 9% and 35% were homozygous (affected) and heterozygous, respectively, for the previously described mutation (mutant allele frequency 0.26). A PK-deficient Cairn Terrier had the same insertion mutation as the affected WHWTs. Of the selected group of 68 Beagles, 35% were PK-deficient and 3% were carriers (0.37).

CONCLUSIONS AND CLINICAL IMPORTANCE

Erythrocytic PK deficiency is caused by different mutations in different dog breeds and causes chronic severe hemolytic anemia, hemosiderosis, and secondary hemochromatosis because of chronic hemolysis and, an as yet unexplained osteosclerosis. The newly developed breed-specific mutation assays simplify the diagnosis of PK deficiency.

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.

Six children with pyruvate kinase deficiency from one small town: molecular characterization of the PK-LR gene

We identified the pyruvate kinase liver/red cell enzyme gene mutation of 8 children previously diagnosed with pyruvate kinase deficiency who were living in a remote town in the western United States. Six were found to be homozygous for the mutation 1529G-A (510 Arg-Gln). Two previously thought to have pyruvate kinase deficiency did not, because they were heterozygous.

Hereditary spherocytosis in neonates with hyperbilirubinemia

OBJECTIVES

Hereditary spherocytosis (HS) is the most common inherited hemolytic disease among people of Northern European decent. Neonates with HS can develop significant hyperbilirubinemia, but we suspect that HS is underrecognized as a cause of neonatal jaundice.

METHODS

We used electronic record repositories of Intermountain Healthcare to identify all neonates with a diagnosis of HS in a recent 5-year period. We compared these with the number of new HS cases anticipated on the basis of national prevalence and also with the number who had elevations in mean corpuscular hemoglobin concentration (MCHC), red cell distribution width (RDW), and bilirubin. We compared MCHC and RDW values of neonates who had direct antiglobulin test-positive (DAT[+]) and DAT(-) results and jaundice with values of neonates who had HS.

RESULTS

Eight neonates received a diagnosis of HS; however, we may have failed to diagnose 90% of cases. To assess whether some with a missed diagnosis of HS developed significant hyperbilirubinemia, we examined records of all 670 with a bilirubin level of >or=20 mg/dL. Records of the 20 with the highest MCHC and RDW values suggested that HS was present but unrecognized in at least 7. Follow-up revealed a subsequent diagnosis of HS in 5; the other 2 are no longer in our health system. MCHC and RDW values were highest in those with HS, intermediate in the DAT(+) group, and lowest in the DAT(-) group. An MCHC of >or=36.0 g/dL had 82% sensitivity and 98% specificity for identifying HS.

CONCLUSION

We speculate that HS is underrecognized as a cause of neonatal hyperbilirubinemia. We speculate further that an MCHC of >or=36.0 g/dL can alert caregivers to the possibility of HS.