5-oxoprolinase Deficiency Research Articles

Acetaminophen Use Concomitant with Long-Lasting Flucloxacillin Therapy: A Dangerous Combination.

Acetaminophen and flucloxacillin both interfere with the γ-glutamyl cycle. Long-lasting concomitant use of flucloxacillin and acetaminophen can lead to 5-oxoproline accumulation and severe high anion gap metabolic acidosis. Females and patients with sepsis, impaired kidney and/or liver function, malnutrition, advanced age, congenital 5-oxoprolinase deficiency and supratherapeutic acetaminophen and flucloxacillin dosage are associated with increased risk. Therefore, a critical attitude towards the prescription of acetaminophen concomitant with flucloxacillin in these patients is needed.We present the case of a 79-year-old woman with severe 5-oxoprolinaemia after long-lasting treatment with flucloxacillin and acetaminophen, explaining the toxicological mechanism and risk factors, and we make recommendations for acetaminophen use in patients with long-lasting flucloxacillin treatment.LEARNING POINTSAlthough rare, long-lasting treatment with flucloxacillin concomitant with acetaminophen can lead to severe high anion gap metabolic acidosis.When prescribing long-lasting flucloxacillin therapy in combination with acetaminophen, regular blood gas analysis is needed to evaluate pH and the anion gap.In cases of 5-oxoproline-induced high anion gap metabolic acidosis in patients with long-lasting acetaminophen and flucloxacillin therapy, acetaminophen prescription should be stopped immediately. Replacing flucloxacillin with another antibiotic agent should be considered.

Unravelling 5-oxoprolinuria (pyroglutamic aciduria) due to bi-allelic OPLAH mutations: 20 new mutations in 14 families.

Primary 5-oxoprolinuria (pyroglutamic aciduria) is caused by a genetic defect in the γ-glutamyl cycle, affecting either glutathione synthetase or 5-oxoprolinase. While several dozens of patients with glutathione synthetase deficiency have been reported, with hemolytic anemia representing the clinical key feature, 5-oxoprolinase deficiency due to OPLAH mutations is less frequent and so far has not attracted much attention. This has prompted us to investigate the clinical phenotype as well as the underlying genotype in patients from 14 families of various ethnic backgrounds who underwent diagnostic mutation analysis following the detection of 5-oxoprolinuria. In all patients with 5-oxoprolinuria studied, bi-allelic mutations in OPLAH were indicated. An autosomal recessive mode of inheritance for 5-oxoprolinase deficiency is further supported by the identification of a single mutation in all 9/14 parent sample sets investigated (except for the father of one patient whose result suggests homozygosity), and the absence of 5-oxoprolinuria in all tested heterozygotes. It is remarkable, that all 20 mutations identified were novel and private to the respective families. Clinical features were highly variable and in several sib pairs, did not segregate with 5-oxoprolinuria. Although a pathogenic role of 5-oxoprolinase deficiency remains possible, this is not supported by our findings. Additional patient ascertainment and long-term follow-up is needed to establish the benign nature of this inborn error of metabolism. It is important that all symptomatic patients with persistently elevated levels of 5-oxoproline and no obvious explanation are investigated for the genetic etiology.

Five Chinese patients with 5-oxoprolinuria due to glutathione synthetase and 5-oxoprolinase deficiencies

5-Oxoprolinuria is a rare inherited metabolic disorder caused by a defective gamma-glutamyl cycle resulting from mutations in the genes encoding 5-oxoprolinase (OPLAH) and glutathione synthetase (GSS). No inherited 5-oxoprolinuria case has been reported in mainland China until now. In this study, clinical, biochemical, and genetic aspects of five Chinese 5-oxoprolinuria patients with OPLAH or GSS gene mutations were investigated. Three boys and two girls from five unrelated Chinese families with symptomatic 5-oxoprolinuria were identified within the past 3years in Peking University First Hospital. OPLAH and GSS genes were analyzed. Patients were hospitalized between the age of 13days to 1year and 3months for hypersomnia, developmental retardation, feeding deficiency, vomiting, icterus and recurrent pneumonia. All patients had significantly elevated urine 5-oxoproline. Three novel mutations (c.1904G>A and c.2813_2815delGGG in Patient 1, c.2978G>T in Patient 2) on OPLAH, on GSS, one novel mutation (c.1252C>T in Patient 3) and a reported mutation (c.491G>A in Patients 3-5) were detected. Patient 4 has homozygous mutation c.491G>A, the others are heterozygous. After treatment by l-carnitine, vitamin E, B1, B2 and coenzyme Q10, three patients with GSS deficiency improved, but the two 5-oxoprolinase-deficient patients did not respond to treatment. 5-Oxoprolinase deficiency and GSS deficiency share some clinical and biochemical features. Genetic analysis is important for the deferential diagnosis. In this study, five Chinese patients had severe central nervous system damage. Antioxidant treatments were proved effective for the three patients with GSS deficiency but not for the two patients with 5-oxoprolinase deficiency.

Pyroglutamic acid-induced metabolic acidosis: a case report

High anion gap metabolic acidosis due to pyroglutamic acid (5-oxoproline) is a rare complication of acetaminophen treatment (which depletes glutathione stores) and is often associated with clinically moderate to severe encephalopathy. Acquired 5-oxoprolinase deficiency (penicillins) or the presence of other risk factors of glutathione depletion such as malnutrition or sepsis seems to be necessary for symptoms development. We report the case of a 55-year-old women who developed a symptomatic overproduction of 5-oxoproline during flucloxacillin treatment for severe sepsis while receiving acetaminophen for fever control. Hemodialysis accelerated the clearance of the accumulated organic acid, and was followed by a sustained clinical improvement.

Rare Case of an Infant with Glutathione Synthetase Deficiency

An infant has generalized Glutathione Synthetase Deficiency. Pyroglutamic Aciduria (5-Oxoprolinuria) is a rare autosomal recessive disorder caused by either Glutathione Synthetase Deficiency or 5-Oxoprolinase Deficiency. The severe form of the disease, generalized GSSD, is characterized by acute Metabolic Acidosis, usually present in the neonatal period with Hemolytic Anemia and Progressive Encephalopathy. We report a male infant who had a severe Metabolic Acidosis with high Anion Gap, Hemolytic Anemia, and Hyperbilirubinemia. High level of Pyruglutamic Acids was detected in his urine. He passed away of severe Metabolic Acidosis and Sepsis.

Madam, why are you so sour?

Madam, why are you so sour?

5‐Oxoprolinase deficiency: report of the first human OPLAH mutation

Gamma-glutamyl cycle is a six-enzyme cycle that represents the primary pathway for glutathione synthesis and degradation. 5-Oxoprolinase deficiency is an extremely rare disorder of the gamma-glutamyl cycle with only eight patients reported to date. Debate continues as to whether this is a benign biochemical defect because of the heterogeneity of the clinical presentation which ranges from normal to significant neurological involvement. Here, we report the first molecularly characterized patients with 5-oxoprolinase deficiency due to a mutation in OPLAH (which encodes 5-oxoprolinase). The largely benign clinical course of the patients described herein despite persistent 5-oxoprolinuria highlights the importance of establishing a molecular diagnosis in the few cases with abnormal neurological outcome to exclude potentially overlapping biochemical defects and to explore potential genotype/phenotype correlation.

Inborn errors in the metabolism of glutathione.

Glutathione is a tripeptide composed of glutamate, cysteine and glycine. Glutathione is present in millimolar concentrations in most mammalian cells and it is involved in several fundamental biological functions, including free radical scavenging, detoxification of xenobiotics and carcinogens, redox reactions, biosynthesis of DNA, proteins and leukotrienes, as well as neurotransmission/neuromodulation. Glutathione is metabolised via the gamma-glutamyl cycle, which is catalyzed by six enzymes. In man, hereditary deficiencies have been found in five of the six enzymes. Glutathione synthetase deficiency is the most frequently recognized disorder and, in its severe form, it is associated with hemolytic anemia, metabolic acidosis, 5-oxoprolinuria, central nervous system (CNS) damage and recurrent bacterial infections. Gamma-glutamylcysteine synthetase deficiency is also associated with hemolytic anemia, and some patients with this disorder show defects of neuromuscular function and generalized aminoaciduria. Gamma-glutamyl transpeptidase deficiency has been found in patients with CNS involvement and glutathionuria. 5-Oxoprolinase deficiency is associated with 5-oxoprolinuria but without a clear association with other symptoms. Dipeptidase deficiency has been described in one patient. All disorders are very rare and inherited in an autosomal recessive manner. Most of the mutations are leaky so that many patients have residual enzyme activity. Diagnosis is made by measuring the concentration of different metabolites in the gamma-glutamyl cycle, enzyme activity and in glutathione synthetase and gamma-glutamylcysteine synthetase deficiency, also by mutation analysis. Prenatal diagnosis has been preformed in glutathione synthetase deficiency. The prognosis is difficult to predict, as few patients are known, but seems to vary significantly between different patients. The aims of the treatment of glutathione synthesis defects are to avoid hemolytic crises and to increase the defense against reactive oxygen species. No treatment has been recommended for gamma-glutamyl transpeptidase, 5-oxoprolinase and dipeptidase deficiency.

Clinical, biochemical, and molecular characterization of patients with glutathione synthetase deficiency.

Pyroglutamic aciduria (5-oxoprolinuria) is a rare autosomal recessive disorder caused by either glutathione synthetase deficiency (GSSD) or 5-oxoprolinase deficiency. GSSD results in low glutathione levels in erythrocytes and may present with hemolytic anemia alone or together with pyroglutamic aciduria, metabolic acidosis, and CNS damage. Five patients with pyroglutamic aciduria were studied. All presented with hemolytic anemia and metabolic acidosis. Two (brothers) also had Fanconi nephropathy, which is not seen in pyroglutamic aciduria. Molecular analyses of the GSS gene was performed in 3 patients. RT-PCR and heteroduplex analysis identified a homozygous deletion in 1 patient and a homozygous mutation in 2 others (brothers with Fanconi nephropathy). Sequencing of glutathione synthetase (GSS) cDNA from the first patient showed a 141-bp deletion corresponding to the entire exon 4, whilst the corresponding genomic DNA showed a G491 --> A homozygous splice site mutation. Sequencing of GSS cDNA from the Fanconi nephropathy patients showed a C847 --> T [ARG283 --> CYS] mutation in exon 9.

5-Oxoprolinuria in patients with and without defects in the gamma-glutamyl cycle.

In patients with defects in the synthesis, breakdown and metabolism of glutathione (GSH), like glutathione synthetase deficiency (GSD) and 5-oxoprolinase deficiency, urinary excretion of 5-oxoproline, an intermediate of the gamma-glutamyl cycle, is increased. We identified 20 patients with significantly elevated urinary excretion of 5-oxoproline (> or =150 mmol/mol creatinine) during 5 years of selective screening for organic acidurias. In 6 of them, 5-oxoprolinuria was a constant finding including three patients with GSD and one with 5-oxoprolinase deficiency. One patient with constant 5-oxoprolinuria had GM2 gangliosidosis and one was clinically unaffected. In 14 patients, 5-oxoprolinuria was a transient abnormality and most often associated with an inborn error of metabolism outside the gamma-glutamyl cycle. In 9 of them 5-oxoprolinuria was associated with a neonatal urea cycle defect, with tyrosinaemia type I or occurred during metabolic decompensation in propionic acidaemia or methylmalonic acidaemia. Additionally, transient 5-oxoprolinuria was associated with homocystinuria, Stevens-Johnson syndrome, paracetamol intoxication, vigabatrin medication or extreme prematurity. 5-Oxoprolinuria is a more common condition than hitherto thought and is primarily associated with defects in the gamma-glutamyl cycle. However, several other inborn errors of metabolism and pathophysiological conditions must be taken into account when discovering 5-oxoprolinuria.

Patients with genetic defects in the γ-glutamyl cycle

In the γ-glutamyl cycle, hereditary defects have been described in four of the six enzymes namely: γ-GC synthetase; GSH synthetase; γ-glutamyl transpeptidase and 5-oxoprolinase. Mutants are still to be found in γ-glutamyl cyclotransferase and in the dipeptidase. Deficiency of GSH synthatase or γ-GC synthetases results in low levels of GSH. In γ-GC synthetase deficiency hemolytic anemia is the most prominent symptom, with or without hepatosplenomegaly. In generalized GSH synthetase deficiency 5-oxoproline is overproduced due to lack of feedback inhibition of γ-GC synthetase. These patients have metabolic acidosis, 5-oxoprolinuria, hemolytic anemia and about 50% of them also have progressive neurological symptoms. Treatment includes acidosis correction, high doses of vitamin E and C and avoidance of drugs precipitating hemolytic crises in G6PD deficiency. Therapeutic trials with GSH analogues, N-acetylcysteine and GSH esters have been carried out. Glutathione synthetase deficiency restricted to erythrocytes results in hemolytic anemia but no 5-oxoprolinuria. γ-Glutamyl transpeptidase deficiency is associated with GSH-emia and GSH-uria whereas 5-oxoprolinase deficiency is associated with 5-oxoprolinuria. In diagnostic work it must be emphasized that erythrocytes contain an incomplete γ-glutamyl cycle; they lack both γ-glutamyl transpeptidase and 5-oxoprolinase and these enzyme activities must therefore be analyzed in other types of cells such as leukocytes and fibroblasts. It is also important to investigate other patients with inherited defects in the γ-glutamyl cycle to learn more about the biological role of GSH in man.

Glycine insufficiency during infancy assessed by urinary 5-oxoproline excretion : A.A. Jackson a, C. Persaud b, N. Evans c, M. Hall b, N. Rutter c and S. Smith b. Departments of aHuman Nutrition and bChild Health, University of Southampton, Bassett Crescent East, Southampton S09 3TU and cDepartment of Child Health, Queen's Medical Centre, University of Nottingham, U.K.

Primary 5-oxoprolinuria (pyroglutamic aciduria) is caused by a genetic defect in the γ-glutamyl cycle, affecting either glutathione synthetase or 5-oxoprolinase. While several dozens of patients with glutathione synthetase deficiency have been reported, with hemolytic anemia representing the clinical key feature, 5-oxoprolinase deficiency due to OPLAH mutations is less frequent and so far has not attracted much attention. This has prompted us to investigate the clinical phenotype as well as the underlying genotype in patients from 14 families of various ethnic backgrounds who underwent diagnostic mutation analysis following the detection of 5-oxoprolinuria.In all patients with 5-oxoprolinuria studied, bi-allelic mutations in OPLAH were indicated. An autosomal recessive mode of inheritance for 5-oxoprolinase deficiency is further supported by the identification of a single mutation in all 9/14 parent sample sets investigated (except for the father of one patient whose result suggests homozygosity), and the absence of 5-oxoprolinuria in all tested heterozygotes. It is remarkable, that all 20 mutations identified were novel and private to the respective families.Clinical features were highly variable and in several sib pairs, did not segregate with 5-oxoprolinuria. Although a pathogenic role of 5-oxoprolinase deficiency remains possible, this is not supported by our findings. Additional patient ascertainment and long-term follow-up is needed to establish the benign nature of this inborn error of metabolism. It is important that all symptomatic patients with persistently elevated levels of 5-oxoproline and no obvious explanation are investigated for the genetic etiology.