Isomerase Deficiency Research Articles

Neuromuscular dysfunction and pathogenesis in triosephosphate isomerase deficiency

Triosephosphate isomerase deficiency (TPI Df) is a rare multisystem disorder with severe neuromuscular symptoms which arises exclusively from mutations within the TPI1 gene. Studies of TPI Df have been limited due to the absence of mammalian disease models and difficulties obtaining patient samples. Recently, we developed a novel murine model of TPI Df which models the most common disease-causing mutation in humans, TPI1E105D. Using our model in the present study, the underlying pathogenesis of neuromuscular symptoms has been elucidated. This is the first report detailing studies of neuromuscular pathology within a murine model of TPI Df. We identified several contributors to neuromuscular symptoms, including neurodegeneration in the brain, alterations in neurotransmission at the neuromuscular junction, and reduced muscle fiber size. TPI Df mice also exhibited signs of cardiac pathology and displayed a deficit in vascular smooth muscle functionality. Together, these findings provide insight into pathogenesis of the neuromuscular symptoms in TPI Df and can guide the future development of therapeutics.

Unusual cause of haemolytic anaemia: Glucose phosphate isomerase deficiency

IntroductionGlucose phosphate isomerase (GPI) deficiency is a rare autosomal recessive disorder that causes hereditary nonspherocytic hemolytic anemia (HNSHA). It is caused by homozygous or compound heterozygous mutation of the GPI gene on chromosome 19q13. Approximately 57 GPI mutations have been reported at the molecular level. Case reportA 4-years and 6-month-old boy presented with progressive pallor along with multiple blood transfusion requirements since four months of age. He had hemolytic anemia associated with macrocytosis, reticulocytosis, neutropenia, and hyperbilirubinemia. Whole-exome sequencing showed that he carried a specific variant in the GPI gene, denoted as c.1040G > A p.Arg347His, which is a homozygous autosomal recessive inherited pathogenic mutation found in exon 12. ConclusionThis report highlights the clinical features and molecular etiology of an Indian patient with GPI deficiency, a rare cause of hereditary hemolytic anemia. A specific variant in the GPI gene was identified through whole-exome sequencing, which is linked to HNSHA. Patients with GPI deficiency require medical management during childhood to monitor for potential complications and prevent hemolytic crises. With optimal management, patients with GPI deficiency can lead a relatively healthy life with normal expectations of growth and development.

Clinico-mutational profile and the impact of splenectomy in children with glucose-6-phosphate isomerase deficiency

BackgroundThere is a lack of literature on the role of splenectomy in hemolytic anemias due to glucose-6-phosphate isomerase (GPI) deficiency. GPI deficiency is a rare red blood cell (RBC) enzymopathy of the glycolytic pathway. Most present with severe disease requiring frequent transfusions. In this study, we report the effect of splenectomy in the world's largest cohort of GPI deficiency patients. The study aimed to describe the clinical, mutational, and laboratory parameters of patients with GPI deficiency. A comparison of the transfusion requirement pre- and post-splenectomy is also included. Material and methodsThe ambispective study was performed from 2017 to 2023. Patients with congenital non-spherocytic hemolytic anemia (CNSHA) were screened for GPI deficiency. Detailed history, including demographic, clinical data, and transfusion details, were noted. Hematological parameters and RBC enzyme activity were estimated using spectrophotometry. The genetic study was done using restriction fragment length polymorphism, and confirmation was obtained through Sanger's sequencing. Patients were followed up after splenectomy. ResultsEighteen patients were diagnosed with GPI deficiency. About 3/4th (14/18; 77.7 %) had significant hepatosplenomegaly. Median serum ferritin levels were 890 ng/ml. Seven patients were on oral iron chelation. The nutritional status assessed as per the Indian Academy of Pediatrics growth charts revealed significant growth retardation. All the patients had severe anemia (mean Hb: 6.4 g/dl) and macrocytosis (mean MCV: 129.2 fl). Laboratory features of hemolysis were evident with reticulocytosis, raised serum lactate dehydrogenase, and indirect bilirubin. The mean GPI enzyme activity was 28.75 IU/g Hb.Ten (55.5 %) patients underwent splenectomy at a median age of 7 years. Five remain transfusion-free post-splenectomy at a median follow-up of 54 months. Other 5 had a significant reduction in transfusion requirement post-splenectomy (p < 0.05). Post-splenectomy, the mean hemoglobin levels increased from 6.2 to 8.1 gm%, and the mean reticulocyte counts reduced from 7.4 % to 4.8 %. Fifteen of 18 had the pathogenic c.1040G > A(p.Arg347His) homozygous mutation. ConclusionThe study demonstrates the benefit of splenectomy in patients with GPI deficiency.

Genetic Analysis of Two Novel GPI Variants Disrupting H Bonds and Localization Characteristics of 55 Gene Variants Associated with Glucose-6-phosphate Isomerase Deficiency.

Glucose-6-phosphate isomerase (GPI) deficiency is a rare hereditary nonspherocytic hemolytic anemia caused by GPI gene variants. This disorder exhibits wide heterogeneity in its clinical manifestations and molecular characteristics, often posing challenges for precise diagnoses using conventional methods. To this end, this study aimed to identify the novel variants responsible for GPI deficiency in a Chinese family. The clinical manifestations of the patient were summarized and analyzed for GPI deficiency phenotype diagnosis. Novel compound heterozygous variants of the GPI gene, c.174C>A (p.Asn58Lys) and c.1538G>T (p.Trp513Leu), were identified using whole-exome and Sanger sequencing. The AlphaFold program and Chimera software were used to analyze the effects of compound heterozygous variants on GPI structure. By characterizing 53 GPI missense/nonsense variants from previous literature and two novel missense variants identified in this study, we found that most variants were located in exons 3, 4, 12, and 18, with a few localized in exons 8, 9, and 14. This study identified novel compound heterozygous variants associated with GPI deficiency. These pathogenic variants disrupt hydrogen bonds formed by highly conserved GPI amino acids. Early family-based sequencing analyses, especially for patients with congenital anemia, can help increase diagnostic accuracy for GPI deficiency, improve child healthcare, and enable genetic counseling.

Glucose phosphate isomerase deficiency demasked by whole-genome sequencing: a case report

BackgroundGlucose-6-phosphate isomerase deficiency is a rare genetic disorder causing hereditary nonspherocytic hemolytic anemia. It is the second most common glycolytic enzymopathy in red blood cells. About 90 cases are reported worldwide, with symptoms including chronic hemolytic anemia, jaundice, splenomegaly, gallstones, cholecystitis, and in severe cases, neurological impairments, hydrops fetalis, and neonatal death.Case presentationThis paper details the case of the first Danish patient diagnosed with glucose-6-phosphate isomerase deficiency. The patient, a 27-year-old white female, suffered from lifelong anemia of unknown origin for decades. Diagnosis was established through whole-genome sequencing, which identified two GPI missense variants: the previously documented variant p.(Thr224Met) and a newly discovered variant p.(Tyr341Cys). The pathogenicity of these variants was verified enzymatically.ConclusionsWhole-genome sequencing stands as a potent tool for identifying hereditary anemias, ensuring optimal management strategies.

Generation and analysis of TPI deficiency zebrafish model.

Triosephosphate isomerase deficiency (TPI DF) is a severe multisystem degenerative disease, manifested clinically as hemolytic anemia, neuromuscular abnormalities, and susceptibility to infection, frequently leading to death within 5 years of onset. There is a lack of effective clinical treatment as the pathogenesis underlying TPI DF remains largely unknown. In this study, we generate a transgenic zebrafish line [Tg(Ubi:TPI1E105D-eGFP)] with the human TPI1E105D (hTPI1E105D) mutation, which is the most recurrent mutation in TPI DF patients. Overexpression of hTPI1E105D affects the development of erythroid and myeloid cells and leads to impaired neural and muscular development. In conclusion, we create a TPI DF zebrafish model to recapitulate the majority clinical features of TPI DF patients, providing a new animal model for pathogenesis study and drug screening of TPI DF.

New Cases of Maleylacetoacetate Isomerase Deficiency with Detection by Newborn Screening and Natural History over 32 Years: Experience from a German Newborn Screening Center.

Newborn screening (NBS) for hepatorenal tyrosinemia type I (HT1) based on a determination of succinylacetone is performed in countries worldwide. Recently, biallelic pathogenic variants in GSTZ1 underlying maleylacetoacetate isomerase (MAAI) deficiency have been described as a differential diagnosis in individuals with slightly elevated succinylacetone detected by NBS. We report the experience with NBS for HT1 over 53 months in a large German NBS center and the identification and characterization of additional cases with MAAI deficiency, including one individual with a natural history over 32 years. A total of 516,803 children underwent NBS for HT1 at the NBS center in Heidelberg between August 2016 and December 2020. Of 42 children with elevated succinylacetone, HT1 was confirmed in two cases (1 in 258.401). MAAI deficiency was suspected in two cases and genetically confirmed in one who showed traces of succinylacetone in urine. A previously unreported pathogenic GSTZ1 variant was found in the index in a biallelic state. Segregation analysis revealed monoallelic carriership in the index case's mother and homozygosity in his father. The 32-year-old father had no medical concerns up to that point and the laboratory work-up was unremarkable. MAAI has to be considered a rare differential diagnosis in NBS for HT1 in cases with slight elevations of succinylacetone to allow for correct counselling and treatment decisions. Our observation of natural history over 32 years adds evidence for a benign clinical course of MAAI deficiency without specific treatment.

Triosephosphate isomerase deficiency in a Tunisian case series

Triosephosphate isomerase deficiency in a Tunisian case series

Glucose-6-phosphate isomerase deficiency hemolysis.

Glucose-6-phosphate isomerase deficiency hemolysis.

Computational analyses of RPIA gene mutation causing Ribose-5-phosphate isomerase deficiency: a rarest known metabolic disorder in humans

The main aim of current study was to perform in silico functional analysis of all reported RPIA mutations. In silico analysis was done using different tools i.e. trRosetta tool, Autodock Vina, PatchDock and iMODS. Among all the reported mutations, lowest percentage identity of 4.69% with wild-type protein was shown by splice site mutation, while highest percentage identity of 78.78%, was shown by p.Ser61Val mutation. In protein-substrate docking, wild-type protein was docking with substrate with 11 different bonds. However in case of mutant protein highest interaction with substrate molecule was shown by mutant p.Ile257Thr proteins via 13 different bonds, while lowest interaction was noted in mutant p.Asn255Ilefs17Term protein via 5 bonds. From the results, it was concluded that the binding of RPIA with ribose 5-phosphate is altered by the type of amino acid substitution, as well as the nature and number of bonds, which are capable to influence its biological activity.

Maleic acid is a biomarker for maleylacetoacetate isomerase deficiency; implications for newborn screening of tyrosinemia type 1.

Dried blood spot succinylacetone (SA) is often used as a biomarker for newborn screening (NBS) for tyrosinemia type 1 (TT1). However, false-positive SA results are often observed. Elevated SA may also be due to maleylacetoacetate isomerase deficiency (MAAI-D), which appears to be clinically insignificant. This study investigated whether urine organic acid (uOA) and quantitative urine maleic acid (Q-uMA) analyses can distinguish between TT1 and MAAI-D. We reevaluated/measured uOA (GC-MS) and/or Q-uMA (LC-MS/MS) in available urine samples of nine referred newborns (2 TT1, 7 false-positive), eight genetically confirmed MAAI-D children, and 66 controls. Maleic acid was elevated in uOA of 5/7 false-positive newborns and in the three available samples of confirmed MAAI-D children, but not in TT1 patients. Q-uMA ranged from not detectable to 1.16 mmol/mol creatinine in controls (n = 66) and from 0.95 to 192.06 mmol/mol creatinine in false-positive newborns and MAAI-D children (n = 10). MAAI-D was genetically confirmed in 4/7 false-positive newborns, all with elevated Q-uMA, and rejected in the two newborns with normal Q-uMA. No sample was available for genetic analysis of the last false-positive infant with elevated Q-uMA. Our study shows that MAAI-D is a recognizable cause of false-positive TT1 NBS results. Elevated urine maleic acid excretion seems highly effective in discriminating MAAI-D from TT1.

The novel compound heterozygous variants identified in a Chinese family with glucose phosphate isomerase deficiency and pathogenicity analysis

Background and Aims:Glucose phosphate isomerase (GPI) deficiency is an extremely rare autosomal recessive disorder caused by mutations in the GPI gene. In this research, the proband displaying typical manifestations of haemolytic anaemia and his family members were recruited to analyse the pathogenicity of the detected variants.Methods:Peripheral blood samples were collected from the family members and genomic DNA was extracted and targeted for capture and sequencing. The effect of the candidate pathogenic variants on splicing was further investigated using the minigene splicing system. The computer simulation was also used for further analysis of the detected data.Results:The proband carried the compound heterozygous variants c.633 + 3 A > G and c.295G > T in the GPI gene, which have never been reported before. In the genealogy, co-segregation of the mutant genotype with the phenotype was established. The minigene study showed that intronic mutations resulted in abnormal pre-mRNA splicing. Specifically, the two aberrant transcripts: r.546_633del and r.633 + 1_633 + 2insGT were transcribed by the minigene plasmid expressing the c.633 + 3 A > G variant. The missense mutation c.295G > T in exon 3 resulted in altering glycine at codon 87 to cysteine which was predicted to be pathogenic in an in silico analysis. Deeper analyses revealed that the Gly87Cys missense mutation led to steric hindrance. Compared to the wild-type, the mutation G87C led to a significant increase in intermolecular forces.Conclusion:Overall, the novel compound heterozygous variants in the GPI gene contributed to the etiology of the disease. Genetic testing can assist in the diagnosis. The novel gene variants identified in the present study has further expanded the mutational spectrum of GPI deficiency, which can better guide family counselling.

GLUOSE 6-PHOSPHATE ISOMERASE DEFICIENCY: A RARE ENTITY

A young male presented to us with the chief complaints of jaundice, non-bilious vomiting and intermittent high-grade fever in the background of past history of recurrent blood transfusions.On examination, he had pallor, icterus with a massive non tender splenomegaly and his laboratory parameters were suggestive of indirect hyperbilirubinemia with low haptoglobin and elevated lactate dehydrogenase levels with reticulocytosis and erythroid hyperplasia on bone marrow aspiration. His Direct and indirect coombs test were negative.To rule out hemoglobinopathies, his hemoglobin electrophoresis was sent, which turned out to be normal. Hence, red blood cell membrane and enzyme studies were carried out which revealed Glucose-6-phosphate isomerase deficiency.

Triose phosphate isomerase deficiency: a rare erythrocyte enzymopathy with a poor prognosis

Triose phosphate isomerase (TPI) is a crucial enzyme for glycolysis. TPI deficiency is an autosomal recessive metabolic disease described in 1965, which remains exceptional by its rarity (less than 100 cases described worldwide), but by its extreme severity. Indeed, it is characterized by a chronic hemolytic anemia, an increased susceptibility to infections and especially, a progressive neurological degeneration which leads to death in early childhood for the majority of cases. We report in our observation the history of diagnosis and clinical course of monozygotic twins born at 32 WA with triose phosphate isomerase deficiency.

Triose-phosphate isomerase deficiency is associated with a dysregulation of synaptic vesicle recycling in Drosophila melanogaster.

Numerous neurodegenerative diseases are associated with neuronal dysfunction caused by increased redox stress, often linked to aberrant production of redox-active molecules such as nitric oxide (NO) or oxygen free radicals. One such protein affected by redox-mediated changes is the glycolytic enzyme triose-phosphate isomerase (TPI), which has been shown to undergo 3-nitrotyrosination (a NO-mediated post-translational modification) rendering it inactive. The resulting neuronal changes caused by this modification are not well understood. However, associated glycation-induced cytotoxicity has been reported, thus potentially causing neuronal and synaptic dysfunction via compromising synaptic vesicle recycling. This work uses Drosophila melanogaster to identify the impacts of altered TPI activity on neuronal physiology, linking aberrant TPI function and redox stress to neuronal defects. We used Drosophila mutants expressing a missense allele of the TPI protein, M81T, identified in a previous screen and resulting in an inactive mutant of the TPI protein (TPIM81T , wstd1). We assessed synaptic physiology at the glutamatergic Drosophila neuromuscular junction (NMJ), synapse morphology and behavioural phenotypes, as well as impacts on longevity. Electrophysiological recordings of evoked and spontaneous excitatory junctional currents, alongside high frequency train stimulations and recovery protocols, were applied to investigate synaptic depletion and subsequent recovery. Single synaptic currents were unaltered in the presence of the wstd1 mutation, but frequencies of spontaneous events were reduced. Wstd1 larvae also showed enhanced vesicle depletion rates at higher frequency stimulation, and subsequent recovery times for evoked synaptic responses were prolonged. A computational model showed that TPI mutant larvae exhibited a significant decline in activity-dependent vesicle recycling, which manifests itself as increased recovery times for the readily-releasable vesicle pool. Confocal images of NMJs showed no morphological or developmental differences between wild-type and wstd1 but TPI mutants exhibited learning impairments as assessed by olfactory associative learning assays. Our data suggests that the wstd1 phenotype is partially due to altered vesicle dynamics, involving a reduced vesicle pool replenishment, and altered endo/exocytosis processes. This may result in learning and memory impairments and neuronal dysfunction potentially also presenting a contributing factor to other reported neuronal phenotypes.

Triosephosphate isomerase deficiency in an infant

Triosephosphate isomerase deficiency is an autosomal recessive disorder characterized by progressive neuromuscular degeneration, seizure, dystonia, weak muscles, cardiomyopathy, hemolytic anemia, and death in early childhood. In the glycolytic pathway, dihydroxy acetone phosphate (DHAP) is converted to glyceraldehyde-3-phosphate by an enzymatic reaction. The reaction is catalyzed by the TPI enzyme. In TPI deficiency, erythrocyte viability is reduced due to insufficient anaerobic respiration and DHAP accumulation causes toxic effects on cells. A 2-month-old boy initially presented with infection and moderate anemia. Respiratory distress and neurological symptoms developed shortly thereafter. He was followed up with a mechanical ventilator for a long time. A homozygous pathogenic variant in the TPI1 gene was detected in the genetic analysis performed due to the progressive neurodegeneration and the need of intermittent erythrocyte transfusion in the follow-up. Here, an infant case with triosephosphate isomerase enzyme deficiency is presented.

Hereditary nonspherocytic hemolytic anemia caused by glucose-6-phosphate isomerase (GPI) deficiency in a Chinese patient: a case report

BackgroundGlucose phosphate isomerase (GPI) deficiency is a rare autosomal recessive disorder that causes hereditary nonspherocytic hemolytic anemia (HNSHA). Homozygous or compound heterozygous mutation of the GPI gene on chromosome 19q13 is the cause of GPI deficiency. Fifty-seven GPI mutations have been reported at the molecular level.Case presentationA 5-month-old boy was presented with repeated episodes of jaundice after birth. He suffered from moderate hemolytic anemia (hemoglobin levels ranging from 62 to 91 g/L) associated with macrocytosis, reticulocytosis, neutropenia, and hyperbilirubinemia. Whole-exome sequencing showed that he has a missense mutation c.301G > A (p.Val101Met) in exon 4 and a frameshift mutation c.812delG (p.Gly271Glufs*131) in exon 10. Mutation p.Gly271Glufs*131 is a novel frameshift null mutation in GPI deficiency.ConclusionIn a patient with recurrent jaundice since birth, mutations in the GPI gene associated with HNSHA should be evaluated. The c.812delG (p.Gly271Glufs*131) variant may be a novel mutation of the GPI gene. Compound heterozygous mutations c.301G > A (p.Val101Met) and c.812delG (p.Gly271Glufs*131) are not relevant to neurological impairment.

Itavastatin and resveratrol increase triosephosphate isomerase protein in a newly identified variant of TPI deficiency.

ABSTRACTTriosephosphate isomerase (TPI) deficiency (TPI Df) is an untreatable glycolytic enzymopathy that results in hemolytic anemia, progressive muscular impairment and irreversible brain damage. Although there is a ‘common’ mutation (TPIE105D), other pathogenic mutations have been described. We identified patients who were compound heterozygous for a newly described mutation, TPIQ181P, and the common TPIE105D mutation. Intriguingly, these patients lacked neuropathy or cognitive impairment. We then initiated biochemical and structural studies of TPIQ181P. Surprisingly, we found that purified TPIQ181P protein had markedly impaired catalytic properties whereas crystallographic studies demonstrated that the TPIQ181P mutation resulted in a highly disordered catalytic lid. We propose that genetic complementation occurs between the two alleles, one with little activity (TPIQ181P) and one with low stability (TPIE105D). Consistent with this, TPIQ181P/E105D fibroblasts exhibit a significant reduction in the TPI protein. These data suggest that impaired stability, and not catalytic activity, is a better predictor of TPI Df severity. Lastly, we tested two recently discovered chemical modulators of mutant TPI stability, itavastatin and resveratrol, and observed a significant increase in TPI in TPIQ181P/E105D patient cells.

Triosephosphate Isomerase Deficiency: The First Case Report from I.R. Iran

Introduction: Triosephosphate isomerase (TPI) deficiency is an autosomal recessive disease and the most severe form of glycolytic enzymopathies, characterized by hemolytic anemia, neurological disorders, infections, and muscle weakness that can affect breathing and heart function. Signs and symptoms include anemia, pallor, jaundice, fatigue, shortness of breath, muscle weakness, atrophy, movement problems, dystonia, tremors, seizures, cardiomyopathy, and diaphragm weakness. Case Presentation: A three-day female newborn was admitted because of hemolytic anemia. All usual assessments for hemolysis, G6PD, osmotic fragility, RBC morphology and cell panel, minor blood groups, antibody screening, and echocardiography were normal. Neurological manifestations appeared after six months of age, including some seizure-like movements, dystonia, and opisthotonus. Whole exome sequencing confirmed the diagnosis of TPI deficiency with the variant NM-000365.5:c.315G&gt;C chr12-6978338(hg19) which revealed the mutation of p.Glu105Asp. By the age of two years, in addition to some drugs for neurologic manifestations and folic acid, the patient was hospitalized every 30 - 45 days for blood transfusion or because of pneumonia. The episodes of pneumonia increased after 24 months of age, and finally, the child expired at the age of 34 months due to pneumonia and respiratory failure. Conclusions: Triosephosphate isomerase deficiency should be considered in all neonates with hemolytic anemia without usual causes.

Hereditary myopathies associated with hematological abnormalities.

The diagnostic evaluation of a patient with suspected hereditary muscle disease can be challenging. Clinicians rely largely on clinical history and examination features, with additional serological, electrodiagnostic, radiologic, histopathologic, and genetic investigations assisting in definitive diagnosis. Hematological testing is inexpensive and widely available, but frequently overlooked in the hereditary myopathy evaluation. Hematological abnormalities are infrequently encountered in this setting; however, their presence provides a valuable clue, helps refine the differential diagnosis, tailors further investigation, and assists interpretation of variants of uncertain significance. A diverse spectrum of hematological abnormalities is associated with hereditary myopathies, including anemias, leukocyte abnormalities, and thrombocytopenia. Recurrent rhabdomyolysis in certain glycolytic enzymopathies co-occurs with hemolytic anemia, often chronic and mild in phosphofructokinase and phosphoglycerate kinase deficiencies, or acute and fever-associated in aldolase-A and triosephosphate isomerase deficiency. Sideroblastic anemia, commonly severe, accompanies congenital-to-childhood onset mitochondrial myopathies including Pearson marrow-pancreas syndrome and mitochondrial myopathy, lactic acidosis, and sideroblastic anemia phenotypes. Congenital megaloblastic macrocytic anemia and mitochondrial dysfunction characterize SFXN4-related myopathy. Neutropenia, chronic or cyclical, with recurrent infections, infantile-to-childhood onset skeletal myopathy and cardiomyopathy are typical of Barth syndrome, while chronic neutropenia without infection occurs rarely in DNM2-centronuclear myopathy. Peripheral eosinophilia may accompany eosinophilic inflammation in recessive calpainopathy. Lipid accumulation in leukocytes on peripheral blood smear (Jordans' anomaly) is pathognomonic for neutral lipid storage diseases. Mild thrombocytopenia occurs in autosomal dominant, childhood-onset STIM1 tubular aggregate myopathy, STIM1 and ORAI1 deficiency syndromes, and GNE myopathy. Herein, we review these hereditary myopathies in which hematological features play a prominent role.