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Cheillan D, Curt MJC, Briand G, Salomons GS, Mention-Mulliez K, Dobbelaere D, Cuisset JM, Lion-François L, Portes VD, Chabli A, Valayannopoulos V, Benoist JF, Pinard JM, Simard G, Douay O, Deiva K, Afenjar A, Héron D, Rivier F, Chabrol B, Prieur F, Cartault F, Pitelet G, Goldenberg A, Bekri S, Gerard M, Delorme R, Tardieu M, Porchet N, Vianey-Saban C, Vamecq J. Screening for primary creatine deficiencies in French patients with unexplained neurological symptoms. Orphanet J Rare Dis 2012; 7:96. [PMID: 23234264 PMCID: PMC3552865 DOI: 10.1186/1750-1172-7-96] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 12/07/2012] [Indexed: 12/11/2022] Open
Abstract
A population of patients with unexplained neurological symptoms from six major French university hospitals was screened over a 28-month period for primary creatine disorder (PCD). Urine guanidinoacetate (GAA) and creatine:creatinine ratios were measured in a cohort of 6,353 subjects to identify PCD patients and compile their clinical, 1H-MRS, biochemical and molecular data. Six GAMT [N-guanidinoacetatemethyltransferase (EC 2.1.1.2)] and 10 X-linked creatine transporter (SLC6A8) but no AGAT (GATM) [L-arginine/glycine amidinotransferase (EC 2.1.4.1)] deficient patients were identified in this manner. Three additional affected sibs were further identified after familial inquiry (1 brother with GAMT deficiency and 2 brothers with SLC6A8 deficiency in two different families). The prevalence of PCD in this population was 0.25% (0.09% and 0.16% for GAMT and SLC6A8 deficiencies, respectively). Seven new PCD-causing mutations were discovered (2 nonsense [c.577C > T and c.289C > T] and 1 splicing [c.391 + 15G > T] mutations for the GAMT gene and, 2 missense [c.1208C > A and c.926C > A], 1 frameshift [c.930delG] and 1 splicing [c.1393-1G > A] mutations for the SLC6A8 gene). No hot spot mutations were observed in these genes, as all the mutations were distributed throughout the entire gene sequences and were essentially patient/family specific. Approximately one fifth of the mutations of SLC6A8, but not GAMT, were attributed to neo-mutation, germinal or somatic mosaicism events. The only SLC6A8-deficient female patient in our series presented with the severe phenotype usually characterizing affected male patients, an observation in agreement with recent evidence that is in support of the fact that this X-linked disorder might be more frequent than expected in the female population with intellectual disability.
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Affiliation(s)
- David Cheillan
- Hospices Civils de Lyon, Service Maladies Héréditaires du Métabolisme et Dépistage Néonatal, Groupement Hospitalier Est, Bron, 69677, France
| | - Marie Joncquel-Chevalier Curt
- Département de Biochimie et Biologie Moléculaire, Laboratoire d’Hormonologie, Métabolisme-Nutrition & Oncologie (HMNO)–Centre de Biologie et Pathologie (CBP) Pierre-Marie Degand, CHRU Lille, Lille, 59037, France
| | - Gilbert Briand
- Département de Biochimie et Biologie Moléculaire, Laboratoire d’Hormonologie, Métabolisme-Nutrition & Oncologie (HMNO)–Centre de Biologie et Pathologie (CBP) Pierre-Marie Degand, CHRU Lille, Lille, 59037, France
- Mass Spectrometry Application Laboratory, University of Lille 2, Lille, 59045, France
| | - Gajja S Salomons
- Metabolic Unit, Department of Clinical Chemistry, VU University Medical Center Amsterdam, Amsterdam, The Netherlands
| | - Karine Mention-Mulliez
- Centre de Référence des Maladies Héréditaires du Métabolisme, Hôpital Jeanne de Flandres, CHRU Lille, Lille, 59037, France
| | - Dries Dobbelaere
- Centre de Référence des Maladies Héréditaires du Métabolisme, Hôpital Jeanne de Flandres, CHRU Lille, Lille, 59037, France
| | - Jean-Marie Cuisset
- Service de Neurologie Infantile, Hôpital Roger Salengro, CHRU Lille, Lille, 59037, France
| | - Laurence Lion-François
- Service de neurologie pédiatrique, CHU de Lyon-GH Est - Hôpital Femme Mère Enfant, Bron Cedex, 69677, France
| | - Vincent Des Portes
- Service de neurologie pédiatrique, CHU de Lyon-GH Est - Hôpital Femme Mère Enfant, Bron Cedex, 69677, France
| | - Allel Chabli
- Laboratory of Biochemistry, Necker – Enfants Malades Hospital and Université Paris Descartes, Paris, 75015, France
| | - Vassili Valayannopoulos
- Centre de Référence des Maladies Héréditaires du Métabolisme, Hôpital Necker des Enfants Malades and Université Paris Descartes, 149 rue de Sèvres, Paris, 75015, France
| | - Jean-François Benoist
- Département de Biochimie-Hormonologie, CHU Hôpital Robert Debré, Paris, 75019, France
| | - Jean-Marc Pinard
- Unité de Neurologie Pédiatrique, Département de Pédiatrie, Hôpital Raymond Poincare, Paris-IdF-Ouest University, Paris, France
| | - Gilles Simard
- Laboratoire de Biochimie et Biologie Moléculaire, CHU Angers, Angers, 49033, France
| | - Olivier Douay
- Laboratoire de Biochimie et Biologie Moléculaire, CHU Angers, Angers, 49033, France
| | - Kumaran Deiva
- Service de Neuropédiatrie - CHU de Bicêtre, Le Kremlin Bicêtre Cedex, 94275, France
| | - Alexandra Afenjar
- Service de Neuropédiatrie, Hôpital Armand Trousseau, Groupement hospitalier universitaire Est, Paris, 75012, France
| | - Delphine Héron
- Unité Fonctionnelle de Génétique Médicale AP-HP, Département de Génétique et Cytogénétique, Centre de Référence «Déficiences intellectuelles de causes rares », CRicm, UMR-S975, Groupe Hospitalier Pitié-Salpêtrière, Paris, F-75013, France
| | - François Rivier
- Neuropédiatrie, CHRU Montpellier, & Inserm U1046, Université Montpellier 1 & 2, Montpellier Cedex 5, 34295, France
| | - Brigitte Chabrol
- Service Neuropédiatrie, AP-HM Hôpital de la Timone, Marseille Cedex 5, 13385, France
| | - Fabienne Prieur
- Service de Génétique, CHU de Saint-Étienne Hôpital Nord, Saint-Etienne Cédex 2, 42055, France
| | - François Cartault
- Service de génétique Centre hospitalier Felix Guyon (Saint-Denis) Bellepierre, Saint-Denis cedex, 97405, France
| | - Gaëlle Pitelet
- Service de Neuropédiatrie, Hôpital de l’Archet 2, Nice Cedex 3, 06202, France
| | - Alice Goldenberg
- Service de Génétique Médicale, CHU Ch. Nicolle, Rouen Cedex, 76031, France
| | - Soumeya Bekri
- Institut de Biologie Clinique, CHU Ch. Nicolle, Rouen Cedex, 76031, France
| | - Marion Gerard
- Service de Génétique, CHU Clémenceau, Caen, 14033, France
| | - Richard Delorme
- Service de Pédopsychiatrie CHU Hôpital Robert Debré, Paris, 75019, France
| | - Marc Tardieu
- Service de Neuropédiatrie - CHU de Bicêtre, Le Kremlin Bicêtre Cedex, 94275, France
| | - Nicole Porchet
- Département de Biochimie et Biologie Moléculaire, Laboratoire d’Hormonologie, Métabolisme-Nutrition & Oncologie (HMNO)–Centre de Biologie et Pathologie (CBP) Pierre-Marie Degand, CHRU Lille, Lille, 59037, France
| | - Christine Vianey-Saban
- Hospices Civils de Lyon, Service Maladies Héréditaires du Métabolisme et Dépistage Néonatal, Groupement Hospitalier Est, Bron, 69677, France
| | - Joseph Vamecq
- Département de Biochimie et Biologie Moléculaire, Laboratoire d’Hormonologie, Métabolisme-Nutrition & Oncologie (HMNO)–Centre de Biologie et Pathologie (CBP) Pierre-Marie Degand, CHRU Lille, Lille, 59037, France
- Inserm, Laboratoire Externe, Département du Prof. Nicole Porchet, HMNO, Centre de Biologie et Pathologie (CBP) Pierre-Marie Degand, CHRU Lille, Lille, 59037, France
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Clark AJ, Rosenberg EH, Almeida LS, Wood TC, Jakobs C, Stevenson RE, Schwartz CE, Salomons GS. X-linked creatine transporter (SLC6A8) mutations in about 1% of males with mental retardation of unknown etiology. Hum Genet 2006; 119:604-10. [PMID: 16738945 DOI: 10.1007/s00439-006-0162-9] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Accepted: 02/21/2006] [Indexed: 10/24/2022]
Abstract
Mutations in the creatine transporter gene, SLC6A8 (MIM 30036), located in Xq28, have been found in families with X-linked mental retardation (XLMR) as well as in males with idiopathic mental retardation (MR). In order to estimate the frequency of such mutations in the MR population, a screening of 478 males with MR of unknown cause was undertaken. All 13 exons of SLC6A8 were sequenced using genomic DNA. Six novel potentially pathogenic mutations were identified that were not encountered in at least 588 male control chromosomes: two deletions (p.Asn336del, p.Ile347del) and a splice site alteration (c.1016+2C>T) are considered pathogenic based on the nature of the variant. A mutation (p.Arg391Trp) should be considered pathogenic owing to its localization in a highly conserved region. Two other missense variants (p.Lys4Arg, p.Gly26Arg) are not conserved but were not observed in over 300 male control chromosomes. Their pathogenicity is uncertain. A missense variant (p.Val182Met), was classified as a polymorphism based on a normal creatine/creatinine (Cr:Crn) ratio and cerebral creatine signal in proton magnetic resonance spectroscopy (H-MRS) in the patient. Furthermore, we found 14 novel intronic and neutral variants that were not encountered in at least 280 male control chromosomes and should be considered as unclassified variants. Our findings of a minimum of four pathogenic mutations and two potentially pathogenic mutations indicate that about 1% of males with MR of unknown etiology might have a SLC6A8 mutation. Thus, DNA sequence analysis and/or a Cr:Crn urine screen is warranted in any male with MR of unknown cause.
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Affiliation(s)
- Amy J Clark
- J.C. Self Research Institute, Greenwood Genetic Center, 1 Gregor Mendel Circle, Greenwood, SC 29646, USA
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Abstract
Mental retardation is more common in males than females in the population, assumed to be due to mutations on the X chromosome. The prevalence of the 24 genes identified to date is low and less common than expansions in FMR1, which cause Fragile X syndrome. Systematic screening of all other X linked genes in X linked families with mental retardation is currently not feasible in a clinical setting. The phenotypes of genes causing syndromic and non-syndromic mental retardation (NLGN3, NLGN4, RPS6KA3(RSK2), OPHN1, ATRX, SLC6A8, ARX, SYN1, AGTR2, MECP2, PQBP1, SMCX, and SLC16A2) are first discussed, as these may be the focus of more targeted mutation analysis. Secondly, the relative prevalence of genes causing only non-syndromic mental retardation (IL1RAPL1, TM4SF2, ZNF41, FTSJ1, DLG3, FACL4, PAK3, ARHGEF6, FMR2, and GDI) is summarised. Thirdly, the problem of recurrence risk where a molecular genetics diagnosis has not been made and what proportion of the male excess of mental retardation is due to monogenic disorders of the X chromosome are discussed.
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Affiliation(s)
- F L Raymond
- Cambridge Institute of Medical Research, Department of Medical Genetics, University of Cambridge, Addenbrooke's Hospital, Cambridge, CB2 2XY, UK.
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