Disorder Of Purine Metabolism Research Articles

How I treat ADA deficiency

AbstractAdenosine deaminase deficiency is a disorder of purine metabolism leading to severe combined immunodeficiency (ADA-SCID). Without treatment, the condition is fatal and requires early intervention. Haematopoietic stem cell transplantation is the major treatment for ADA-SCID, although survival following different donor sources varies considerably. Unlike other SCID forms, 2 other options are available for ADA-SCID: enzyme replacement therapy (ERT) with pegylated bovine ADA, and autologous haematopoietic stem cell gene therapy (GT). Due to the rarity of the condition, the lack of large scale outcome studies, and availability of different treatments, guidance on treatment strategies is limited. We have reviewed the currently available evidence and together with our experience of managing this condition propose a consensus management strategy. Matched sibling donor transplants represent a successful treatment option with high survival rates and excellent immune recovery. Mismatched parental donor transplants have a poor survival outcome and should be avoided unless other treatments are unavailable. ERT and GT both show excellent survival, and therefore the choice between ERT, MUD transplant, or GT is difficult and dependent on several factors, including accessibility to the different modalities, response of patients to long-term ERT, and the attitudes of physicians and parents to the short- and potential long-term risks associated with different treatments.

Pegademase bovine (PEG-ADA) for the treatment of infants and children with severe combined immunodeficiency (SCID

Adenosine deaminase deficiency (ADA) is a rare, inherited disorder of purine metabolism characterized by immunodeficiency, failure to thrive and metabolic abnormalities. A lack of the enzyme ADA allows accumulation of toxic metabolites causing defects of both cell mediated and humoral immunity leading to ADA severe combined immune deficiency (SCID), a condition that can be fatal in early infancy if left untreated. Hematopoietic stem cell transplant is curative but is dependent on a good donor match. Other therapeutic options include enzyme replacement therapy (ERT) with pegademase bovine (PEG-ADA) and more recently gene therapy. PEG-ADA has been used in over 150 patients worldwide and has allowed stabilization of patients awaiting more definitive treatment with hematopoietic stem cell transplant. It affords both metabolic detoxification and protective immune function with patients remaining clinically well, but immune reconstitution is often suboptimal and may not be long lived. We discuss the pharmacokinetics, immune reconstitution, effects on systemic disease and side effects of treatment with PEG-ADA. We also review the long-term outcome of patients receiving ERT and discuss the role of PEG-ADA in the management of infants and children with ADA-SCID, alongside other therapeutic options.

Pegademase bovine (PEG-ADA) for the treatment of infants and children with severe combined immunodeficiency (SCID

Pegademase bovine (PEG-ADA) for the treatment of infants and children with severe combined immunodeficiency (SCID Claire Booth1,2, H Bobby Gaspar1,21Centre for Immunodeficiency, Molecular Immunology Unit, UCL Institute of Child Health, London, UK; 2Dept of Clinical Immunology, Great Ormond Street Hospital NHS Trust, London, UKAbstract: Adenosine deaminase deficiency (ADA) is a rare, inherited disorder of purine metabolism characterized by immunodeficiency, failure to thrive and metabolic abnormalities. A lack of the enzyme ADA allows accumulation of toxic metabolites causing defects of both cell mediated and humoral immunity leading to ADA severe combined immune deficiency (SCID), a condition that can be fatal in early infancy if left untreated. Hematopoietic stem cell transplant is curative but is dependent on a good donor match. Other therapeutic options include enzyme replacement therapy (ERT) with pegademase bovine (PEG-ADA) and more recently gene therapy. PEG-ADA has been used in over 150 patients worldwide and has allowed stabilization of patients awaiting more definitive treatment with hematopoietic stem cell transplant. It affords both metabolic detoxification and protective immune function with patients remaining clinically well, but immune reconstitution is often suboptimal and may not be long lived. We discuss the pharmacokinetics, immune reconstitution, effects on systemic disease and side effects of treatment with PEG-ADA. We also review the long-term outcome of patients receiving ERT and discuss the role of PEG-ADA in the management of infants and children with ADA-SCID, alongside other therapeutic options.Keywords: adenosine deaminase deficiency, PEG-ADA, enzyme replacement therapy, severe combined immune deficiency (SCID)

Characterization of genotype ‐ phenotype correlations in Adenylosuccinate Lyase (ADSL) Deficiency

ADSL deficiency is inherited disorder of purine metabolism affecting mainly central nervous system. Three forms differing in severity of symptoms and correlating negatively with ratios of accumulating SAdo/SAICAr in body fluids were established. The mechanisms leading to selective neuronopathy and underlying the clinical and biochemical heterogeneity are unknown.We analysed 22 patients, identified 16 ADSL mutations, expressed and characterized catalytic properties of recombinant wild type and mutant proteins, investigated expression patterns of ADSL in available tissues from 3 patients and correlated these data with patients' clinical and biochemical presentation.We found that phenotype severity corresponds with residual enzyme activity (calculated as a mean of homoallelic activities), but the mutant enzymes displayed proportional decrease in activity to both of its substrates, so no ground for the varied SAdo/SAICAr ratios was found.Western blot and immunohistochemistry analyses showed in patients generally reduced amounts of ADSL in investigated tissues.Our results suggest that selective affection of central nervous system is caused by toxic effects of accumulating SAdo‐SAICAr. Phenotype's heterogeneity may be explained by differential activity of metabolite transport across blood‐brain barrier in individual cases.This work was supported by grants GACR 301070600 and MSM CR 20620806.

Inborn errors of purine and pyrimidine metabolism

Genetic disorders of purine and pyrimidine (PP) metabolism are under-reported and infrequently mentioned in the general literature, as well as in reviews dedicated to other inborn errors of metabolism. Owing to limited awareness, relatively recent recognition, as well as considerable phenotypic variation, these disorders may often be misdiagnosed or remain undiagnosed. Disorders that arise as a result of dysfunction in PP metabolism represent some of the most challenging diagnostic problems in medicine. In addition to their low prevalence rates, they also present with extremely variable signs and symptoms. They may affect any system in a variety of manners, and often mimic other, more recognizable disorders. The diagnostic problem is compounded by the fact that some biochemically affected patients are symptom-free. Rapidly evolving laboratory techniques such as high-performance liquid chromatography coupled to tandem mass spectrometry are now well established as the preferred method for detection for these defects, but currently the most important step in diagnosis consists of suspecting the disorder. Diagnosis is vital because genetic counselling can be provided and, in some cases, specific treatment can be offered that may slow or even reverse clinical symptoms. If undiagnosed, these disorders can be devastating to patients and their families, resulting in early death or institutionalization for the rest of patient's life. This article describes the current state of knowledge about inborn errors of purine and pyrimidine metabolism, focusing on the varying clinical presentations, the laboratory findings and discusses indications for selective screening for these disorders.

Gene Therapy for Immunodeficiency Due to Adenosine Deaminase Deficiency

We investigated the long-term outcome of gene therapy for severe combined immunodeficiency (SCID) due to the lack of adenosine deaminase (ADA), a fatal disorder of purine metabolism and immunodeficiency. We infused autologous CD34+ bone marrow cells transduced with a retroviral vector containing the ADA gene into 10 children with SCID due to ADA deficiency who lacked an HLA-identical sibling donor, after nonmyeloablative conditioning with busulfan. Enzyme-replacement therapy was not given after infusion of the cells. All patients are alive after a median follow-up of 4.0 years (range, 1.8 to 8.0). Transduced hematopoietic stem cells have stably engrafted and differentiated into myeloid cells containing ADA (mean range at 1 year in bone marrow lineages, 3.5 to 8.9%) and lymphoid cells (mean range in peripheral blood, 52.4 to 88.0%). Eight patients do not require enzyme-replacement therapy, their blood cells continue to express ADA, and they have no signs of defective detoxification of purine metabolites. Nine patients had immune reconstitution with increases in T-cell counts (median count at 3 years, 1.07x10(9) per liter) and normalization of T-cell function. In the five patients in whom intravenous immune globulin replacement was discontinued, antigen-specific antibody responses were elicited after exposure to vaccines or viral antigens. Effective protection against infections and improvement in physical development made a normal lifestyle possible. Serious adverse events included prolonged neutropenia (in two patients), hypertension (in one), central-venous-catheter-related infections (in two), Epstein-Barr virus reactivation (in one), and autoimmune hepatitis (in one). Gene therapy, combined with reduced-intensity conditioning, is a safe and effective treatment for SCID in patients with ADA deficiency. (ClinicalTrials.gov numbers, NCT00598481 and NCT00599781.)

Gouty Synovitis of the Knee with Partial Hypoxanthine-guanine Phosphoribosyl Transferase Deficiency (Kelley-Seegmiller Syndrome): A Case Report

We present here a case of gouty synovitis of the knee in a patient with partial hypoxanthine-guanine phosphoribosyl transferase deficiency (Kelley-Seegmiller syndrome), which is an inherited purine metabolic disorder. Magnetic resonance images and computed tomography showed a diffuse mass with stippled calcification around the posterior cruciate ligament (PCL) in the posterior intercondylar notch. Arthroscopic examination revealed that the articular surfaces and menisci in the affected knee were almost completely covered with white chalky monosodium urate (MSU) crystals. The diffuse mass around the PCL was composed of proliferative synovial villi covered with MSU crystals that looked like snow covered trees. Arthroscopic total synovectomy was performed. The posterior trans-septal portal was especially useful for removal of the proliferative villi around the PCL. To our knowledge, this is the first report of arthroscopic examination in a patient with Kelley-Seegmiller syndrome.

Hormonal and Biochemical Parameters of Metabolic Syndrome in Male Patients with Body Weight Excess and Obesity

Developed form of metabolic syndrome was revealed in 64.3% men with grade 1 obesity and in 81.8% men with grade 2-3 obesity (patients of the therapeutic clinic). The major components were dyslipidemia, fatty hepatosis, arterial hypertension, and hyperinsulinemia. In patients with excess body weight, changes in some biochemical parameters also attested to the presence of some components of the metabolic syndrome, but purine metabolism disorders were more frequently observed in this group than hyperinsulinemia.

Levodopa therapy in a Lesch‐Nyhan disease patient: Pathological, biochemical, neuroimaging, and therapeutic remarks

Lesch-Nyhan disease (LND) is a hereditary disorder of purine metabolism causing severe neurobehavioral disturbances in which an abnormal central nervous system dopaminergic function has been implied. However, levodopa treatment has rarely been used, and reports describe heterogeneous responses. We report an LND patient with low dopamine metabolite values in cerebrospinal fluid for whom early levodopa/carbidopa therapy was begun with a notable clinical improvement. We propose that very early treatment of LND patients with levodopa may improve their neurological symptoms and may contribute to a better outcome.

Lithiases urinaires récidivantes révélant une xanthinurie héréditaire

Hereditary xanthinuria, due to a purine metabolism disorder, is a rare cause of urinary lithiasis in children. We report the case of a child aged 3 and a half years, who presented recurrent urinary lithiasis that led to destruction of the right kidney. Infrared spectrophotometric analysis of the calculus concluded that it was composed of 100% xanthine. Laboratory tests showed hypouricemia and hypouricosuria with elevated urinary excretion of oxypurines. These findings led to a diagnosis of hereditary xanthinuria. Early diagnosis of this rare disease is essential to avoid its complications. Metabolic causes must be sought in children with lithiasis.

Kelley-Seegmiller-Syndrom

Hypoxanthinguanin-phosphoribosyltransferase (HPRT) deficiency, an x-linked inherited disease can cause two presentations: A complete deficiency (Lesch-Nyhan syndrome) accompanies with grave renal and neurological symptoms. A second form is the partial enzyme deficiency (Kelley-Seegmiller syndrome). We present a thirteen year old boy with relapsing hyperuricemia and hypercreatininemia. In the framework of postoperative renal insufficiency the diagnose of a Kelley-Seegmiller syndrome was elaborated. About 25% of patients with Kelley-Seegmiller syndrome present mild neurological symptoms but never with self-destructive behavior. Pathophysiological an increased de novo purinsynthesis is present. Therefore, it comes to an overproduction of urine acid. Urolithiasis is one clinical manifestation. Relapsing urolithiasis and renal insufficiency has to be worked up. In the differential diagnosis a disorder of purine metabolism has to be discussed.

Xanthinuria type I: a rare cause of urolithiasis

Xanthinuria type I is a rare disorder of purine metabolism caused by xanthine oxidoreductase or dehydrogenase (XDH) deficiency. We report a family with two affected children out of 335 pediatric stone patients studied since 1991 in Armenia. The propositus, a 13-month-old boy, presented with abdominal pain and urinary retention followed by stone passage (0.9x0.6 cm). Infrared spectroscopy in Yerevan revealed a pure xanthine stone. Family examination in the parents and brother was normal, but the propositus and his 8-year-old asymptomatic sister had hypouricemia, hypouricosuria, and high urinary excretion of hypoxanthine and xanthine. Ultrasonography in the index patient showed bilateral stones requiring pyelolithotomy. High fluid intake and purine restriction did not prevent further stone passages. The affected asymptomatic sister had a small pelvic stone (4 mm). Mutation analysis revealed a heterozygous novel base pair substitution in exon 25 of the XDH gene (c.2810C>T), resulting in an amino acid substitution (p.Thr910Met). The second mutation could not be detected. Despite this, the heterozygous mutation, the chemical findings, and the positive allopurinol test altogether prove xanthinuria type I, which may present wide clinical intrafamilial variation. Diagnosis is suspected usually from low serum uric acid. No specific therapy is available.

Comprehensive Detection of Disorders of Purine and Pyrimidine Metabolism by HPLC with Electrospray Ionization Tandem Mass Spectrometry

Clinical presentation and disease severity in disorders of purine and pyrimidine metabolism vary considerably. We present a method that allows comprehensive, sensitive, and specific diagnosis of the entire spectrum of abnormalities in purine and pyrimidine metabolism in 1 analytical run. We used reversed-phase HPLC electrospray ionization tandem mass spectrometry to investigate 24 metabolites of purine and pyrimidine metabolism in urine samples from healthy persons and from patients with confirmed diagnoses of inherited metabolic disorders. Urine samples were filtered and diluted to a creatinine concentration of 0.5 mmol/L. Stable-isotope-labeled internal standards were used for quantification. The metabolites were analyzed by multiple-reaction monitoring in positive and negative ionization modes. Total time of analysis was 20 min. Recovery (n = 8) of a compound after addition of a known concentration was 85%-133%. The mean intraday variation (n = 10) was 12%. The interday variation (n = 7) was < or =17%. Age-related reference intervals were established for each compound. Analysis of patient urine samples revealed major differences in tandem mass spectrometry profiles compared with those of control samples. Twelve deficiencies were reliably detected: hypoxanthine guanine phosphoribosyl transferase, xanthine dehydrogenase, purine nucleoside phosphorylase, adenylosuccinate lyase, uridine monophosphate synthase, adenosine deaminase, adenine phosphoribosyl transferase, molybdenum cofactor, thymidine phosphorylase, dihydropyrimidine dehydrogenase, dihydropyrimidinase, and beta-ureidopropionase. This method enables reliable detection of 13 defects in purine and pyrimidine metabolism in a single analytical run.

The purine metabolism of human erythrocytes

This review summarizes currently available information about a crucial part of erythrocyte metabolism, that is, purine nucleotide conversions and their relationships with other conversion pathways. We describe the cellular resynthesis, interconversion, and degradation of purine compounds, and also the regulatory mechanisms in the conversion pathways. We also mention purine metabolism disorders and their clinical consequences. The literature is fragmentary because studies have concentrated only on selected aspects of purine metabolism; hence the need for a synthetic approach.

Purine Metabolites in Gout and Asymptomatic Hyperuricemia: Analysis by HPLC–Electrospray Tandem Mass Spectrometry

Hyperuricemia, a serum urate concentration >0.45 mmol/L (7.0 mg/dL) in men and 0.36 mmol/L (6.0 mg/dL) in women, is the biochemical hallmark of gout (1)(2)(3), but many individuals with life-long hyperuricemia do not develop gouty arthritis (4). Conversely, serum urate concentrations may be within reference values in some patients with acute gout, particularly during the early phases of the disorder. We hypothesized that gout patients may have a different profile of purine precursors than do asymptomatic people with hyperuricemia and that concentrations of these compounds may reflect disorders of purine metabolism. To our knowledge, purine metabolites have not been studied and compared in gout and asymptomatic hyperuricemia. With established methods for measuring purine compounds in blood and urine (5)(6)(7)(8)(9), retention time is not always adequate for identification of every peak because urine and blood usually contain many interfering compounds. Quantification by tandem mass spectrometry (MS/MS) (10)(11) may require an internal standard, which often is hard to obtain. In this study of 10 purine compounds in the blood of gout patients and hyperuricemia patients with no gout symptoms, we used HPLC for serum sample separation, MS/MS for peak identification, and ultraviolet (UV) detection for quantification. Purines were purchased from Fluka and Sigma. The HPLC-MS experiment was performed on an Agilent 1100 series liquid chromatograph with a mass spectrometric detector trap. Separation was carried out on a Supelcosil™ LC-18-DB column [25 cm × 4.6 mm (i.d.); 5-μm film thickness]. The column temperature was maintained at 25 °C. The mobile phases were as follows: 10 mmol/L ammonium acetate, adjusted to pH 6.5 with glacial acetic acid (eluant A), and methanol (eluant B). The elution gradient was as follows (flow rate, 1 mL/min): 0 to 10 …

Simultaneous determination of 16 purine derivatives in urinary calculi by gradient reversed-phase high-performance liquid chromatography with UV detection

A reversed-phase high-performance liquid chromatography (HPLC) method with ultraviolet detection has been developed for the analysis of purines in urinary calculi. The method using gradient of methanol concentration and pH was able to separate 16 compounds: uric acid, 2,8-dihydroxyadenine, xanthine, hypoxanthine, allopurinol and oxypurinol as well as 10 methyl derivatives of uric acid or xanthine (1-, 3-, 7- and 9-methyluric acid, 1,3-, 1,7- and 3,7-dimethyluric acid, 1-, 3- and 7-methylxanthine). Limits of detection for individual compounds ranged from 0.006 to 0.035 mg purine/g of the stone weight and precision (CV%) was 0.5–2.4%. The method enabled us to detect in human uric acid stones admixtures of nine other purine derivatives: natural metabolites (hypoxanthine, xanthine, 2,8-dihydroxyadenine) and methylated purines (1-, 3- and 7-methyluric acid, 1,3-dimethyluric acid, 3- and 7-methylxanthine) originating from the metabolism of methylxanthines (caffeine, theophylline and theobromine). The method allows simultaneous quantitation of all known purine constituents of urinary stones, including methylated purines, and may be used as a reference one for diagnosing disorders of purine metabolism and research on the pathogenesis of urolithiasis.

Inherited disorders of purine and pyrimidine metabolism. State of art. Contribution for diagnosis

Inherited errors of purine and pyrimidine metabolism are a group of disorders with a broad spectrum of clinical manifestations. They may involve nervous, renal, haematological and immunological systems, presenting at any age. The incidence and prevalence of these disorders are unknown. Most clinicians are not aware of their existence and hospital laboratories do not offer conditions for the screening. We have been associated contractor in an european project for the study of these disorders. It enabled us to set up urinary screening methods and establish normal values for urinary purine and pyrimidine in our paediatric population.

Simple non-radiochemical HPLC-linked method for screening for purine metabolism disorders using dried blood spot

Background: Pathologies associated with rare inherited disorders affecting purine metabolic pathways range from renal failure to neurological dysfunction and immunodeficiency. The disorders are usually diagnosed by measuring enzyme activities in hemolysates. A non-radiochemical HPLC-linked method is described for simultaneous determination of the activities of hypoxanthine-guanine phosphoribosyltransferase (HPRT: E.2.4.2.8.), adenine phosphoribosyltransferase (APRT: E.2.4.2.7.), adenosine deaminase (ADA: E.3.5.4.4.) and purine nucleoside phosphorylase (PNP: E.2.4.2.1.) in dried blood spots. Method: 7-mm-diameter blood spots stored at 4 °C or room temperature were transferred to an Eppendorf tube and eluted with 500-μl 0.1 mol/l Tris–HCl buffer, pH 7.4. The eluate was added to substrate solutions and incubated at 37 °C. Reaction products were analysed by HPLC. Results and conclusions: The enzyme activities tested in spot eluates were similar to those in erythrocyte lysates from the same subjects. None of the enzymatic activities tested were significantly affected by different storage temperatures. The main advantages of the proposed method are small blood volume required, easy sample collection and transfer, and accurate results. The method is therefore suitable for screening inborn errors of purine metabolism even in newborns.

Purine Composition of the Crystalline Cytoplasmic Inclusions of Paramecium tetraurelia

Crystalline cytoplasmic inclusions were isolated by differential centrifugation from mass cultures of Paramecium tetraurelia feeding on Klebsiella pneumonia. Physical and chemical measurements of intact and solubilized crystals determined that they consist primarily of guanine and hypoxanthine with traces of xanthine. Crystals from the mutant sombre consist primarily of xanthine, suggesting there is a disorder of purine metabolism in this mutant.

Capillary electrophoresis for detection of inherited disorders of purine and pyrimidine metabolism: a selective approach.

We developed a capillary electrophoresis method as a diagnostic tool for purine and pyrimidine metabolic disorders. Optimal conditions allowed the separation of the major diagnostic metabolites in urine samples within an analysis time of 10 min and with a separation efficiency of about 350,000 theoretical plates/m. The diagnostically important metabolites (adenine, adenosine, 2-deoxyadenosine, 2-deoxyguanosine, 2,8-dihydroxyadenine, guanosine, hypoxanthine, orotidine, orotic acid, and creatinine) were detectable at concentrations of 1.0-5.7 micromol/L. The method gives a linear calibration curve for tested purine and pyrimidine derivatives within the range of 5-500 micromol/L (r > 0.996) The coefficients of variation for the within- and between-day imprecisions were less than 3.2 and 5.8%, respectively. Characteristic abnormalities were detected in the electropherograms of urine samples from patients with purine and pyrimidine enzyme deficiencies. We provide electrophoretic and spectral characteristics of intermediates in purine and pyrimidine metabolism and possible artifacts from medication and their UV-absorbing compounds. Our method allows the detection of the majority of inborn errors of purine and pyrimidine metabolism.