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Sellos-Moura M, Glavin F, Lapidus D, Evans KA, Palmer L, Irwin DE. Estimated prevalence of moderate to severely elevated total homocysteine levels in the United States: A missed opportunity for diagnosis of homocystinuria? Mol Genet Metab 2020; 130:36-40. [PMID: 32057642 DOI: 10.1016/j.ymgme.2020.02.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 01/27/2020] [Accepted: 02/04/2020] [Indexed: 12/31/2022]
Abstract
Classical homocystinuria (HCU) is a genetic disorder caused by mutations in the cystathionine beta synthase gene, which results in impaired metabolism of the sulfur-bearing amino acid homocysteine and its accumulation in blood and tissues. Classical HCU can be detected via newborn screening in the United States, but the test is widely acknowledged to miss many patients. While severely elevated homocysteine levels (>100 μmol /L) frequently lead to a classical HCU diagnosis, intermediate levels (>30 to 100 μmol /L), though linked to many of the known complications of HCU, are not always recognized as associated with HCU. We aimed to identify and describe potentially undiagnosed classical HCU patients using a nationally-representative database of administrative claims and laboratory results. We estimated the national prevalence of patients with homocysteine >30 μmol /L, and compared their demographic and clinical characteristics to those of patients with homocysteine levels ≤30 μmol/L. Among 57,580 patients with a homocysteine test result, 1.8% had a value >30 μmol /L. Patients with homocysteine >30 μmol /L were more frequently diagnosed with hypothyroidism (39.2% vs. 20.7%, p < .001) and renal disease (9.7% vs. 5.5%, p < .001), and were more likely to have a prescription for an anxiolytic/antidepressant (44.5% vs. 38.9%), opioid (58.4% vs. 53.1%), steroid (46.4% vs. 42.5%), or thyroid hormone (38.8% vs. 18.8%), compared to patients with homocysteine ≤30 μmol /L (all p < .05). Both groups were equally likely to have a diagnosis of homocystinuria or another disorder of sulfur-bearing amino acid metabolism (3.8% vs. 4.0%, p = .752). The age-adjusted national prevalence of homocysteine >30 μmol /L was estimated at 33,068 (95% CI: 1033 - 35,104). These findings suggest that thousands of people in the US may be living with intermediate to severely elevated homocysteine levels and may require further evaluation for the presence of classical HCU.
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Affiliation(s)
| | - Frank Glavin
- Orphan Technologies, 430 Bedford St, Lexington, MA 02420, USA.
| | - David Lapidus
- LapidusData Inc., 321 NE 4th St, Oklahoma City, OK 73104, USA.
| | | | - Liisa Palmer
- IBM Watson Health, 75 Binney St, Cambridge, MA 02142, USA.
| | - Debra E Irwin
- IBM Watson Health, 75 Binney St, Cambridge, MA 02142, USA.
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Sellos-Moura M, Glavin F, Lapidus D, Evans K, Lew CR, Irwin DE. Prevalence, characteristics, and costs of diagnosed homocystinuria, elevated homocysteine, and phenylketonuria in the United States: a retrospective claims-based comparison. BMC Health Serv Res 2020; 20:183. [PMID: 32143624 PMCID: PMC7059682 DOI: 10.1186/s12913-020-5054-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 02/28/2020] [Indexed: 11/10/2022] Open
Abstract
Background Classical homocystinuria (HCU), an inborn error of homocysteine metabolism, has previously been estimated to affect approximately 1 in 100,000–200,000 people in the United States (US). HCU is poorly detected by newborn screening, resulting in underestimates of its prevalence. This study compared characteristics, healthcare use and costs, and projected prevalence between patients with diagnosed HCU, elevated total homocysteine (tHcy), and diagnosed phenylketonuria (PKU). Methods Patients in the MarketScan® Research Databases were identified with strictly-defined HCU (> 2 diagnoses, including 1 ICD-10), broadly-defined HCU (> 1 ICD-10), elevated tHcy (> 20 μmol/L) without an HCU diagnosis, or > 1 ICD-9/ICD-10 PKU diagnosis during 1/1/2010–12/31/2016 (first qualifying claim = index). Demographics and healthcare utilization and costs per patient per month (PPPM) were compared between all cohorts, frequencies of comorbidities and medications were compared between HCU and elevated tHcy patients, and healthcare provider types were assessed among HCU patients. The prevalence of patients meeting each cohort definition was projected to the United States (US) population. Results Patients with strictly-defined (N = 2450) and broadly-defined (N = 6613) HCU, and with elevated tHcy (N = 2017), were significantly older than PKU patients (N = 5120) (57 vs. 56 vs. 53 vs. 18 years; p < 0.05). Vitamin D deficiency, hyperlipidemia, folic acid/B vitamins, and lipid-lowering medications, among others, were more common among diagnosed HCU patients vs. those with elevated tHcy (all p < 0.05). Rates of healthcare utilization were generally higher among HCU and elevated tHcy patients, compared to PKU, though total healthcare costs were similar between groups. Most HCU patients (~ 38%) received their index diagnosis from a primary care physician; very few (~ 1%) had any claim from a geneticist during their enrollment. The age-adjusted national prevalence of HCU was projected at 31,162 (95% CI: 30,411 – 31,913; ~ 1 in 10,000 of the US population) using the broad definition. Conclusions The actual prevalence of HCU may be > 10 times prior estimates, at 1 in 10,000 in the US, and this study suggests that HCU is not being diagnosed until later in life. Improvements to newborn screening, detection in young children, and physician education regarding HCU among patients may be necessary to alleviate the burden of this genetic disease.
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Affiliation(s)
| | - Frank Glavin
- Orphan Technologies, 430 Bedford St, Lexington, MA, 02420, USA
| | - David Lapidus
- LapidusData Inc, 321 NE 4th St, Oklahoma City, OK, 73104, USA
| | - Kristin Evans
- IBM Watson Health, 75 Binney St, Cambridge, MA, 02142, USA
| | - Carolyn R Lew
- IBM Watson Health, 75 Binney St, Cambridge, MA, 02142, USA
| | - Debra E Irwin
- IBM Watson Health, 75 Binney St, Cambridge, MA, 02142, USA
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Bax BE, Levene M, Bain MD, Fairbanks LD, Filosto M, Kalkan Uçar S, Klopstock T, Kornblum C, Mandel H, Rahman S, Roubertie A, Scarpelli M, Sedgwick PM, Baru M, Sellos-Moura M, Price J, Horn P, Nirmalananthan N. Erythrocyte Encapsulated Thymidine Phosphorylase for the Treatment of Patients with Mitochondrial Neurogastrointestinal Encephalomyopathy: Study Protocol for a Multi-Centre, Multiple Dose, Open Label Trial. J Clin Med 2019; 8:jcm8081096. [PMID: 31344955 PMCID: PMC6722784 DOI: 10.3390/jcm8081096] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 07/19/2019] [Accepted: 07/23/2019] [Indexed: 02/05/2023] Open
Abstract
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder which primarily affects the gastrointestinal and nervous systems. This disease is caused by mutations in the nuclear TYMP gene, which encodes for thymidine phosphorylase, an enzyme required for the normal metabolism of deoxynucleosides, thymidine, and deoxyuridine. The subsequent elevated systemic concentrations of deoxynucleosides lead to increased intracellular concentrations of their corresponding triphosphates, and ultimately mitochondrial failure due to progressive accumulation of mitochondrial DNA (mtDNA) defects and mtDNA depletion. Currently, there are no treatments for MNGIE where effectiveness has been evidenced in clinical trials. This Phase 2, multi-centre, multiple dose, open label trial without a control will investigate the application of erythrocyte-encapsulated thymidine phosphorylase (EE-TP) as an enzyme replacement therapy for MNGIE. Three EE-TP dose levels are planned with patients receiving the dose level that achieves metabolic correction. The study duration is 31 months, comprising 28 days of screening, 90 days of run-in, 24 months of treatment and 90 days of post-dose follow-up. The primary objectives are to determine the safety, tolerability, pharmacodynamics, and efficacy of multiple doses of EE-TP. The secondary objectives are to assess EE-TP immunogenicity after multiple dose administrations and changes in clinical assessments, and the pharmacodynamics effect of EE-TP on clinical assessments.
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Affiliation(s)
- Bridget E Bax
- Molecular and Clinical Sciences, St. George's, University of London, London SW17 0RE, UK.
| | - Michelle Levene
- Molecular and Clinical Sciences, St. George's, University of London, London SW17 0RE, UK
| | - Murray D Bain
- Molecular and Clinical Sciences, St. George's, University of London, London SW17 0RE, UK
| | | | - Massimiliano Filosto
- Centre for Neuromuscular Diseases, ASST Spedali Civili and University of Brescia, 25100 Brescia, Italy
| | - Sema Kalkan Uçar
- Division of Inborn Error of Metabolism, Ege University Medical Faculty, 35100 Izmir, Turkey
| | - Thomas Klopstock
- Department of Neurology, Friedrich-Baur-Institute, University of Munich, Ziemssenstr. 1, 80336 Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), Ludwig Maximilians University, Geschwister-Scholl-Platz 1, 80539 Munich, Germany
- German Center for Neurodegenerative Diseases (DZNE), Feodor-Lynen-Strasse 17, 81377 Munich, Germany
| | - Cornelia Kornblum
- Department of Neurology, University Hospital Bonn, 53127 Bonn, Germany
| | | | - Shamima Rahman
- Mitochondrial Research Group, UCL London Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
- Metabolic Unit, Great Ormond Street Hospital NHS Foundation Trust, London WC1N 3JH, UK
| | - Agathe Roubertie
- Department of Pediatric Neurology, Centre Hospitalier Universitaire de Montpellier, 34295 Montpellier, France
| | - Mauro Scarpelli
- Institute of Neurology, University of Verona, 37126 Verona, Italy
| | - Philip M Sedgwick
- Institute for Medical and Biomedical Education, St George's, University of London, London SW17 0RE, UK
| | - Moshe Baru
- Orphan Technologies, Zürcherstrasse 19, 8640 Rapperswil, Switzerland
| | | | - Jeanie Price
- Orphan Technologies, Zürcherstrasse 19, 8640 Rapperswil, Switzerland
| | | | - Niranjanan Nirmalananthan
- Molecular and Clinical Sciences, St. George's, University of London, London SW17 0RE, UK
- Department of Neurology, St George's University Hospitals NHS Foundation Trust, London SW17 0QT, UK
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Levene M, Pacitti D, Gasson C, Hall J, Sellos-Moura M, Bax BE. Validation of an Immunoassay for Anti-thymidine Phosphorylase Antibodies in Patients with MNGIE Treated with Enzyme Replacement Therapy. Mol Ther Methods Clin Dev 2018; 11:1-8. [PMID: 30294618 PMCID: PMC6170929 DOI: 10.1016/j.omtm.2018.08.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 08/21/2018] [Indexed: 02/08/2023]
Abstract
Erythrocyte encapsulated thymidine phosphorylase is recombinant Escherichia coli thymidine phosphorylase encapsulated within human autologous erythrocytes and is under development as an enzyme replacement therapy for the ultra-rare inherited metabolic disorder mitochondrial neurogastrointestinal encephalomyopathy. This study describes the method validation of a two-step bridging electrochemiluminescence immunoassay for the detection of anti-thymidine phosphorylase antibodies in human serum according to current industry practice and regulatory guidelines. The analytical method was assessed for screening cut point, specificity, selectivity, precision, prozone effect, drug tolerance, and stability. Key findings were a correction factor of 129 relative light units for the cut-point determination; a specificity cut point of 93% inhibition; confirmed intra-assay and inter-assay precision; assay sensitivity of 356 ng/mL; no matrix or prozone effects up to 25,900 ng/mL; a drug tolerance of 156 ng/mL; and stability at room temperature for 24 hr and up to five freeze-thaws. Immunogenicity evaluations of serum from three patients who received erythrocyte encapsulated thymidine phosphorylase under a compassionate treatment program showed specific anti-thymidine phosphorylase antibodies in one patient. To conclude, a sensitive, specific, and selective immunoassay has been validated for the measurement of anti-thymidine phosphorylase antibodies; this will be utilized in a phase II pivotal clinical trial of erythrocyte encapsulated thymidine phosphorylase.
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Affiliation(s)
- Michelle Levene
- Molecular & Clinical Sciences Research Institute, St. George’s, University of London, London, UK
| | - Dario Pacitti
- Molecular & Clinical Sciences Research Institute, St. George’s, University of London, London, UK
| | - Charlotte Gasson
- Biomarker, Bioanalysis and Clinical Sciences, Envigo CRS, Cambridgeshire, UK
| | - Jamie Hall
- Biomarker, Bioanalysis and Clinical Sciences, Envigo CRS, Cambridgeshire, UK
| | | | - Bridget E. Bax
- Molecular & Clinical Sciences Research Institute, St. George’s, University of London, London, UK
- Corresponding author: Bridget E. Bax, Molecular & Clinical Sciences Research Institute, St George’s, University of London, London SW17 0RE, UK.
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Dali CÍ, Barton NW, Farah MH, Moldovan M, Månsson JE, Nair N, Dunø M, Risom L, Cao H, Pan L, Sellos-Moura M, Corse AM, Krarup C. Sulfatide levels correlate with severity of neuropathy in metachromatic leukodystrophy. Ann Clin Transl Neurol 2015; 2:518-33. [PMID: 26000324 PMCID: PMC4435706 DOI: 10.1002/acn3.193] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2015] [Accepted: 02/04/2015] [Indexed: 11/10/2022] Open
Abstract
Objective Metachromatic leukodystrophy (MLD) is an autosomal recessive lysosomal storage disorder due to deficient activity of arylsulfatase A (ASA) that causes accumulation of sulfatide and lysosulfatide. The disorder is associated with demyelination and axonal loss in the central and peripheral nervous systems. The late infantile form has an early-onset, rapidly progressive course with severe sensorimotor dysfunction. The relationship between the degree of nerve damage and (lyso)sulfatide accumulation is, however, not established. Methods In 13 children aged 2–5 years with severe motor impairment, markedly elevated cerebrospinal fluid (CSF) and sural nerve sulfatide and lysosulfatide levels, genotype, ASA mRNA levels, residual ASA, and protein cross-reactive immunological material (CRIM) confirmed the diagnosis. We studied the relationship between (lyso)sulfatide levels and (1) the clinical deficit in gross motor function (GMFM-88), (2) median and peroneal nerve motor and median and sural nerve sensory conduction studies (NCS), (3) median and tibial nerve somatosensory evoked potentials (SSEPs), (4) sural nerve histopathology, and (5) brain MR spectroscopy. Results Eleven patients had a sensory-motor demyelinating neuropathy on electrophysiological testing, whereas two patients had normal studies. Sural nerve and CSF (lyso)sulfatide levels strongly correlated with abnormalities in electrophysiological parameters and large myelinated fiber loss in the sural nerve, but there were no associations between (lyso)sulfatide levels and measures of central nervous system (CNS) involvement (GMFM-88 score, SSEP, and MR spectroscopy). Interpretation Nerve and CSF sulfatide and lysosulfatide accumulation provides a marker of disease severity in the PNS only; it does not reflect the extent of CNS involvement by the disease process. The magnitude of the biochemical disturbance produces a continuously graded spectrum of impairments in neurophysiological function and sural nerve histopathology.
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Affiliation(s)
- Christine Í Dali
- Department of Clinical Genetics, Rigshospitalet Copenhagen, Denmark
| | | | - Mohamed H Farah
- Department of Neurology, Johns Hopkins Medical Institutions Baltimore, Maryland
| | - Mihai Moldovan
- Department of Clinical Neurophysiology, Rigshospitalet Copenhagen, Denmark ; Department of Neuroscience and Pharmacology, University of Copenhagen Copenhagen, Denmark
| | - Jan-Eric Månsson
- Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital Gothenburg, Sweden
| | | | - Morten Dunø
- Department of Clinical Genetics, Rigshospitalet Copenhagen, Denmark
| | - Lotte Risom
- Department of Clinical Genetics, Rigshospitalet Copenhagen, Denmark
| | | | | | | | - Andrea M Corse
- Department of Neurology, Johns Hopkins Medical Institutions Baltimore, Maryland
| | - Christian Krarup
- Department of Clinical Neurophysiology, Rigshospitalet Copenhagen, Denmark ; Department of Neuroscience and Pharmacology, University of Copenhagen Copenhagen, Denmark
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Schiffmann R, Murray GJ, Treco D, Daniel P, Sellos-Moura M, Myers M, Quirk JM, Zirzow GC, Borowski M, Loveday K, Anderson T, Gillespie F, Oliver KL, Jeffries NO, Doo E, Liang TJ, Kreps C, Gunter K, Frei K, Crutchfield K, Selden RF, Brady RO. Infusion of alpha-galactosidase A reduces tissue globotriaosylceramide storage in patients with Fabry disease. Proc Natl Acad Sci U S A 2000; 97:365-70. [PMID: 10618424 PMCID: PMC26669 DOI: 10.1073/pnas.97.1.365] [Citation(s) in RCA: 252] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Fabry disease is a lysosomal storage disorder caused by a deficiency of the lysosomal enzyme alpha-galactosidase A (alpha-gal A). This enzymatic defect results in the accumulation of the glycosphingolipid globotriaosylceramide (Gb(3); also referred to as ceramidetrihexoside) throughout the body. To investigate the effects of purified alpha-gal A, 10 patients with Fabry disease received a single i.v. infusion of one of five escalating dose levels of the enzyme. The objectives of this study were: (i) to evaluate the safety of administered alpha-gal A, (ii) to assess the pharmacokinetics of i.v.-administered alpha-gal A in plasma and liver, and (iii) to determine the effect of this replacement enzyme on hepatic, urine sediment and plasma concentrations of Gb(3). alpha-Gal A infusions were well tolerated in all patients. Immunohistochemical staining of liver tissue approximately 2 days after enzyme infusion identified alpha-gal A in several cell types, including sinusoidal endothelial cells, Kupffer cells, and hepatocytes, suggesting diffuse uptake via the mannose 6-phosphate receptor. The tissue half-life in the liver was greater than 24 hr. After the single dose of alpha-gal A, nine of the 10 patients had significantly reduced Gb(3) levels both in the liver and shed renal tubular epithelial cells in the urine sediment. These data demonstrate that single infusions of alpha-gal A prepared from transfected human fibroblasts are both safe and biochemically active in patients with Fabry disease. The degree of substrate reduction seen in the study is potentially clinically significant in view of the fact that Gb(3) burden in Fabry patients increases gradually over decades. Taken together, these results suggest that enzyme replacement is likely to be an effective therapy for patients with this metabolic disorder.
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Affiliation(s)
- R Schiffmann
- Developmental and Metabolic Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892-1260, USA.
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