title: Sanfilippo syndrome type C: mutation spectrum in the heparan sulfate acetyl-CoA: alpha-glucosaminide N-acetyltransferase (HGSNAT) gene.
abstract: Mucopolysaccharidosis (MPS) type IIIC or Sanfilippo syndrome type C is a rare autosomal recessive disorder caused by the deficiency of the lysosomal membrane enzyme, heparan sulfate acetyl-CoA (AcCoA): alpha-glucosaminide N-acetyltransferase (HGSNAT; EC 2.3.1.78), which catalyzes transmembrane acetylation of the terminal glucosamine residues of heparan sulfate prior to their hydrolysis by alpha-N-acetylglucosaminidase. Lysosomal storage of undegraded heparan sulfate in the cells of affected patients leads to neuronal death, causing neurodegeneration and severely impaired development accompanied by mild visceral and skeletal abnormalities, including mild dwarfism, coarse facies, and joint stiffness. To date, 50 HGSNAT mutations have been identified in MPS IIIC patients: 40 were previously published and 10 novel mutations are reported here. The mutations span the entire structure of the gene and include 13 splice-site mutations, 11 insertions and deletions, 8 nonsense mutations, and 18 missense mutations (http://chromium.liacs.nl/LOVD2/home.php?select_db=HGSNAT). In addition, four polymorphisms result in amino acid changes that do not affect activity of the enzyme. In this work we discuss the spectrum of MPS IIIC mutations, their clinical presentation and distribution within the patient population, and speculate how the mutations may affect the structure and function of HGSNAT.
authors.affiliation: Department of Medical Genetics, University Hospital Center Sainte-Justine, University of Montreal, Montreal, Canada.
authors.forename: Matthew
authors.initials: M
authors.lastname: Feldhammer
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Durand
authors.forename: Lenka
authors.initials: L
authors.lastname: Mrázová
authors.forename: Renée-Myriam
authors.initials: RM
authors.lastname: Boucher
authors.forename: Rachel
authors.initials: R
authors.lastname: Laframboise
authors.forename: Robert
authors.initials: R
authors.lastname: Steinfeld
authors.forename: James E
authors.initials: JE
authors.lastname: Wraith
authors.forename: Helen
authors.initials: H
authors.lastname: Michelakakis
authors.forename: Otto P
authors.initials: OP
authors.lastname: van Diggelen
authors.forename: Martin
authors.initials: M
authors.lastname: Hrebícek
authors.forename: Stanislav
authors.initials: S
authors.lastname: Kmoch
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Pshezhetsky
mesh_terms: D000123:Acetyltransferases / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D006801:Humans; D008969:Molecular Sequence Data; D009084:Mucopolysaccharidosis III / Q000175:diagnosis / Q000201:enzymology* / Q000235:genetics* / Q000473:pathology; D009154:Mutation / Q000235:genetics*
chemical_list: D000123:Acetyltransferases; C514442:HGSNAT protein, human