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Mercimek-Mahmutoglu S, Pop A, Kanhai W, Fernandez Ojeda M, Holwerda U, Smith D, Loeber JG, Schielen PCJI, Salomons GS. A pilot study to estimate incidence of guanidinoacetate methyltransferase deficiency in newborns by direct sequencing of the GAMT gene. Gene 2015; 575:127-31. [PMID: 26319512 DOI: 10.1016/j.gene.2015.08.045] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 08/21/2015] [Accepted: 08/23/2015] [Indexed: 11/17/2022]
Abstract
BACKGROUND GAMT deficiency is an autosomal recessive disorder of creatine biosynthesis causing developmental delays or intellectual disability in untreated patients as a result of irreversible brain damage occurring prior to diagnosis. Normal neurodevelopmental outcome has been reported in patients treated from neonatal period highlighting the importance of early treatment. METHODS Five hundred anonymized newborns from the National Newborn Screening Program of The Netherlands were included into this pilot study. Direct sequencing of the coding region of the GAMT gene was applied following DNA extraction. The disease causing nature of novel missense variants in the GAMT gene was studied by overexpression studies. GAA and creatine was measured in blood dot spots. RESULTS We detected two carriers, one with a known common (c.327G>A) and one with a novel mutation (c.297_309dup (p.Arg105Glyfs*) in the GAMT gene. The estimated incidence of GAMT deficiency was 1:250,000. We also detected five novel missense variants. Overexpression of these variants in GAMT deficient fibroblasts did restore GAMT activity and thus all were considered rare, but not disease causing variants including the c.131G>T (p.Arg44Leu) variant. Interestingly, this variant was predicted to be pathogenic by in silico analysis. The variants were included in the Leiden Open Variation Database (LOVD) database (www.LOVD.nl/GAMT). The average GAA level was 1.14μmol/L±0.45 standard deviations. The average creatine level was 408μmol/L±106. The average GAA/creatine ratio was 2.94±0.136. CONCLUSION The estimated incidence of GAMT deficiency is 1:250,000 newborns based on our pilot study. The newborn screening for GAMT deficiency should be implemented to identify patients at the asymptomatic stage to achieve normal neurodevelopmental outcome for this treatable neurometabolic disease. Biochemical investigations including GAA, creatine and GAMT enzyme activity measurements are essential to confirm the diagnosis of GAMT deficiency. According to availability, all missense variants can be assessed functionally, as in silico prediction analysis of missense variants is not sufficient to confirm the pathogenicity of missense variants.
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Affiliation(s)
- S Mercimek-Mahmutoglu
- Division of Clinical and Metabolic Genetics, Department of Pediatrics, University of Toronto, Canada; Genetics and Genome Biology, Research Institute, The Hospital for Sick Children, Toronto, Canada.
| | - A Pop
- Metabolic Unit, Department of Clinical Chemistry, VU Medical Center, Neurosciences Campus, Amsterdam, The Netherlands
| | - W Kanhai
- Metabolic Unit, Department of Clinical Chemistry, VU Medical Center, Neurosciences Campus, Amsterdam, The Netherlands
| | - M Fernandez Ojeda
- Metabolic Unit, Department of Clinical Chemistry, VU Medical Center, Neurosciences Campus, Amsterdam, The Netherlands
| | - U Holwerda
- Metabolic Unit, Department of Clinical Chemistry, VU Medical Center, Neurosciences Campus, Amsterdam, The Netherlands
| | - D Smith
- Metabolic Unit, Department of Clinical Chemistry, VU Medical Center, Neurosciences Campus, Amsterdam, The Netherlands
| | - J G Loeber
- National Institute for Public Health and the Environment, Centre for Infectious Diseases Research, and Screening, Bilthoven, The Netherlands
| | - P C J I Schielen
- National Institute for Public Health and the Environment, Centre for Infectious Diseases Research, and Screening, Bilthoven, The Netherlands
| | - G S Salomons
- Metabolic Unit, Department of Clinical Chemistry, VU Medical Center, Neurosciences Campus, Amsterdam, The Netherlands.
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van de Kamp JM, Betsalel OT, Mercimek-Mahmutoglu S, Abulhoul L, Grünewald S, Anselm I, Azzouz H, Bratkovic D, de Brouwer A, Hamel B, Kleefstra T, Yntema H, Campistol J, Vilaseca MA, Cheillan D, D’Hooghe M, Diogo L, Garcia P, Valongo C, Fonseca M, Frints S, Wilcken B, von der Haar S, Meijers-Heijboer HE, Hofstede F, Johnson D, Kant SG, Lion-Francois L, Pitelet G, Longo N, Maat-Kievit JA, Monteiro JP, Munnich A, Muntau AC, Nassogne MC, Osaka H, Ounap K, Pinard JM, Quijano-Roy S, Poggenburg I, Poplawski N, Abdul-Rahman O, Ribes A, Arias A, Yaplito-Lee J, Schulze A, Schwartz CE, Schwenger S, Soares G, Sznajer Y, Valayannopoulos V, Van Esch H, Waltz S, Wamelink MMC, Pouwels PJW, Errami A, van der Knaap MS, Jakobs C, Mancini GM, Salomons GS. Phenotype and genotype in 101 males with X-linked creatine transporter deficiency. J Med Genet 2013; 50:463-72. [DOI: 10.1136/jmedgenet-2013-101658] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Mercimek-Mahmutoglu S, Sinclair G, van Dooren SJM, Kanhai W, Ashcraft P, Michel OJ, Nelson J, Betsalel OT, Sweetman L, Jakobs C, Salomons GS. Guanidinoacetate methyltransferase deficiency: first steps to newborn screening for a treatable neurometabolic disease. Mol Genet Metab 2012; 107:433-7. [PMID: 23031365 DOI: 10.1016/j.ymgme.2012.07.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 07/27/2012] [Indexed: 01/10/2023]
Abstract
BACKGROUND GAMT deficiency is an autosomal recessive disorder of creatine biosynthesis resulting in severe neurological complications in untreated patients. Currently available treatment is only successful to stop disease progression, but is not sufficient to reverse neurological complications occurring prior to diagnosis. Normal neurodevelopmental outcome in a patient, treated in the newborn period, highlights the importance of early diagnosis. METHODS Targeted mutation analysis (c.59G>C and c.327G>A) in the GAMT gene by the QIAxcel system and GAA measurement by a novel two-tier method were performed in 3000 anonymized newborn blood dot spot cards. RESULTS None of the targeted mutations were detected in any newborn. Two novel heterozygous variants (c.283_285dupGTC; p.Val95dup and c.278_283delinsCTCGATGCAC; p.Asp93AlafsX35) were identified by coincidence. Carrier frequency for these insertion/deletion types of GAMT mutations was 1/1475 in this small cohort of newborns. GAA levels were at or above the 99th percentile (3.12 μmol/l) in 4 newborns. Second-tier testing showed normal results for 4 newborns revealing 0.1% false positive rate. No GAMT mutations were identified in 4 of the newborns with elevated GAA levels in the first tier testing. CONCLUSION This is the first two-tier study to investigate carrier frequency of GAMT deficiency in the small cohort of newborn population to establish evidence base for the first steps toward newborn screening for this treatable neurometabolic disorder.
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Affiliation(s)
- S Mercimek-Mahmutoglu
- Division of Clinical and Metabolic Genetics, Department of Pediatrics, University of Toronto, Toronto, ON, Canada.
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van der Lei HDW, van Berkel CGM, van Wieringen WN, Brenner C, Feigenbaum A, Mercimek-Mahmutoglu S, Philippart M, Tatli B, Wassmer E, Scheper GC, van der Knaap MS. Genotype-phenotype correlation in vanishing white matter disease. Neurology 2010; 75:1555-9. [PMID: 20975056 DOI: 10.1212/wnl.0b013e3181f962ae] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE Vanishing white matter (VWM) is an autosomal recessive leukoencephalopathy characterized by slowly progressive ataxia and spasticity with additional stress-provoked episodes of rapid and major deterioration. The disease is caused by mutations in the genes encoding the subunits of eukaryotic initiation factor 2B, which is pivotal in translation of mRNAs into proteins. The disease onset, clinical severity, and disease course of VWM vary greatly. The influence of genotype and gender on the phenotype is unclear. METHODS From our database of 184 patients with VWM, we selected those with the following mutations in the gene EIF2B5: p.Arg113His in the homozygous state (n = 23), p.Arg113His in the compound-heterozygous state (n = 49), p.Thr91Ala in the homozygous state (n = 8), p.Arg113His/p.Arg339any (n = 9), and p.Thr91Ala/p.Arg339any (n = 7). We performed a cross-sectional observational study. Evaluated clinical characteristics were gender, age at onset, age at loss of walking without support, and age at death. Means, male/female ratios, and Kaplan-Meier curves were compared. RESULTS Patients homozygous for p.Arg113His had a milder disease than patients compound heterozygous for p.Arg113His and patients homozygous for p.Thr91Ala. Patients with p.Arg113His/p.Arg339any had a milder phenotype than patients with p.Thr91Ala/p.Arg339any. Overall, females tended to have a milder disease than males. CONCLUSIONS The clinical phenotype in VWM is influenced by the combination of both mutations. Females tend to do better than males.
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Affiliation(s)
- H D W van der Lei
- Department of Child Neurology, VU University Medical Center, Amsterdam, the Netherlands
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Mercimek-Mahmutoglu S, Moeslinger D, Häberle J, Engel K, Herle M, Strobl MW, Scheibenreiter S, Muehl A, Stöckler-Ipsiroglu S. Long-term outcome of patients with argininosuccinate lyase deficiency diagnosed by newborn screening in Austria. Mol Genet Metab 2010; 100:24-8. [PMID: 20236848 DOI: 10.1016/j.ymgme.2010.01.013] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2010] [Accepted: 01/24/2010] [Indexed: 11/16/2022]
Abstract
Twenty-three patients with late onset argininosuccinate lyase deficiency (ASLD) were identified during a 27-year period of newborn screening in Austria (1:95,600, 95% CI=1:68,036-1:162,531). One additional patient was identified outside the newborn screening with neonatal hyperammonemia. Long-term outcome data were available in 17 patients (median age 13 years) ascertained by newborn screening. Patients were treated with protein restricted diet and oral arginine supplementation during infancy and childhood. IQ was average/above average in 11 (65%), low average in 5 (29%), and in the mild intellectual disability range in 1 (6%) patients. Four patients had an abnormal EEG without evidence of clinical seizures and three had abnormal liver function tests and/or evidence of hepatic steatosis. Plasma citrulline levels were elevated in four patients. Plasma ammonia levels were within normal range prior and after a protein load in all patients. Seven different mutations were identified in the 16 alleles investigated. Four mutations were novel (p.E189G, p.R168C, p.R126P, and p.D423H). All mutations were associated with low argininosuccinate lyase activities (0-15%) in red blood cells. Newborn screening might be beneficial in the prevention of chronic neurologic and intellectual sequelae in late onset ASLD, but a proportion of benign variants might have contributed to the overall favorable outcome as well.
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Affiliation(s)
- S Mercimek-Mahmutoglu
- Department of Pediatrics, Division of Biochemical Diseases, British Columbia University, Vancouver, BC, Canada
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Mercimek-Mahmutoglu S, Ipsiroglu OS, Feucht M, Buchta-Scheicher B, Haas O, Prayer D, Stöckler-Ipsiroglu S. Wolf-Hirschhorn-Syndrom und frühkindliche Epilepsie. Monatsschr Kinderheilkd 2007. [DOI: 10.1007/s00112-006-1377-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Mercimek-Mahmutoglu S, Stoeckler-Ipsiroglu S, Adami A, Appleton R, Araújo HC, Duran M, Ensenauer R, Fernandez-Alvarez E, Garcia P, Grolik C, Item CB, Leuzzi V, Marquardt I, Mühl A, Saelke-Kellermann RA, Salomons GS, Schulze A, Surtees R, van der Knaap MS, Vasconcelos R, Verhoeven NM, Vilarinho L, Wilichowski E, Jakobs C. GAMT deficiency: Features, treatment, and outcome in an inborn error of creatine synthesis. Neurology 2006; 67:480-4. [PMID: 16855203 DOI: 10.1212/01.wnl.0000234852.43688.bf] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [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: 11/15/2022] Open
Abstract
BACKGROUND Guanidinoactetate methyltransferase (GAMT) deficiency is an autosomal recessive disorder of creatine synthesis. The authors analyzed clinical, biochemical, and molecular findings in 27 patients. METHODS The authors collected data from questionnaires and literature reports. A score including degree of intellectual disability, epileptic seizures, and movement disorder was developed and used to classify clinical phenotype as severe, moderate, or mild. Score and biochemical data were assessed before and during treatment with oral creatine substitution alone or with additional dietary arginine restriction and ornithine supplementation. RESULTS Intellectual disability, epileptic seizures, guanidinoacetate accumulation in body fluids, and deficiency of brain creatine were common in all 27 patients. Twelve patients had severe, 12 patients had moderate, and three patients had mild clinical phenotype. Twenty-one of 27 (78%) patients had severe intellectual disability (estimated IQ 20 to 34). There was no obvious correlation between severity of the clinical phenotype, guanidinoacetate accumulation in body fluids, and GAMT mutations. Treatment resulted in almost normalized cerebral creatine levels, reduced guanidinoacetate accumulation, and in improvement of epilepsy and movement disorder, whereas the degree of intellectual disability remained unchanged. CONCLUSION Guanidinoactetate methyltransferase deficiency should be considered in patients with unexplained intellectual disability, and urinary guanidinoacetate should be determined as an initial diagnostic approach.
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Affiliation(s)
- S Mercimek-Mahmutoglu
- Division of Biochemical Diseases, British Columbia Children's Hospital, Vancouver, Canada
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Mercimek-Mahmutoglu S, van der Knaap MS, Baric I, Prayer D, Stoeckler-Ipsiroglu S. Hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC). Report of a new case. Neuropediatrics 2005; 36:223-6. [PMID: 15944912 DOI: 10.1055/s-2005-865715] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC) syndrome is a new neurodegenerative entity, which was first described by van der Knaap in 2002 in 7 patients aged from 2 months to 2 years. We describe a new, 42-month-old female patient who developed progressive dystonia, spasticity and oculogyric eye movements since the age of 3 months. The diagnosis was made by characteristic MRI findings including supratentorial hypomyelination and progressive atrophy of basal ganglia and cerebellum. Oculogyric eye movements have not been described in patients with H-ABC syndrome before. When compared with the normal age-related myelination patterns, the degree of hypomyelination increased progressively over the time course of 32 months, indicating arrest but not loss of myelination. The H-ABC syndrome adds to the differential diagnosis of progressive pyramidal and extrapyramidal movement disorders and to the increasing number of genetically determined hypomyelination syndromes.
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Item CB, Mercimek-Mahmutoglu S, Battini R, Edlinger-Horvat C, Stromberger C, Bodamer O, Mühl A, Vilaseca MA, Korall H, Stöckler-Ipsiroglu S. Characterization of seven novel mutations in seven patients with GAMT deficiency. Hum Mutat 2004; 23:524. [PMID: 15108290 DOI: 10.1002/humu.9238] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [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: 11/08/2022]
Abstract
Guanidinoacetate methyltransferase (GAMT) deficiency is an autosomal recessive error of creatine synthesis characterized by cerebral creatine deficiency, accumulation of guanidinoacetate, mental retardation, epilepsy and extrapyramidal signs. So far, six mutations have been identified in seven patients. We investigated seven new patients by screening the promoter, 3'UTR, and six exons and exon/intron boundaries using direct sequencing and denaturing gradient gel electrophoresis. The clinical and biochemical phenotype was characterized by scoring the degree of main clinical manifestations and by determination of urinary guanidinoacetate concentrations and of GAMT activity in fibroblasts / lymphoblasts, respectively. We identified 7 novel mutations, including c.64dupG (exon 1; 4/14 alleles); c.59G>C (exon 1; 3/14 alleles); c.491delG (exon 5; 2/14 alleles); c.160G>C (exon 1; 2/14 alleles); and c.152A>C (exon 1; 1/14 alleles); c.526dupG (exon 5; 1/14 alleles); c.521G>A (exon 5; 1/14 alleles), and two polymorphisms c.626C>T (exon 6) and c.459+71G>A (intron 4). Frameshift and missense mutations in exon 1 were prevalent in the 4 patients with the severe phenotype, however a clear genotype-phenotype correlation has not been established in the limited number of patients characterized so far.
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Affiliation(s)
- C B Item
- Department of Pediatrics, and National Newborn Screening Laboratory, University Hospital and General Hospital of Vienna, Austria
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