Mutations in TMEM76* cause mucopolysaccharidosis IIIC (Sanfilippo C syndrome)

Am J Hum Genet. 2006 Nov;79(5):807-19. doi: 10.1086/508294. Epub 2006 Sep 8.


Mucopolysaccharidosis IIIC (MPS IIIC, or Sanfilippo C syndrome) is a lysosomal storage disorder caused by the inherited deficiency of the lysosomal membrane enzyme acetyl-coenzyme A: alpha -glucosaminide N-acetyltransferase (N-acetyltransferase), which leads to impaired degradation of heparan sulfate. We report the narrowing of the candidate region to a 2.6-cM interval between D8S1051 and D8S1831 and the identification of the transmembrane protein 76 gene (TMEM76), which encodes a 73-kDa protein with predicted multiple transmembrane domains and glycosylation sites, as the gene that causes MPS IIIC when it is mutated. Four nonsense mutations, 3 frameshift mutations due to deletions or a duplication, 6 splice-site mutations, and 14 missense mutations were identified among 30 probands with MPS IIIC. Functional expression of human TMEM76 and the mouse ortholog demonstrates that it is the gene that encodes the lysosomal N-acetyltransferase and suggests that this enzyme belongs to a new structural class of proteins that transport the activated acetyl residues across the cell membrane.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetyltransferases / chemistry
  • Acetyltransferases / genetics*
  • Acetyltransferases / metabolism
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cell Line
  • Chromosome Mapping
  • Chromosomes, Human, Pair 8 / genetics
  • Cloning, Molecular
  • DNA Mutational Analysis
  • DNA, Complementary / genetics
  • Exons
  • Female
  • Gene Expression
  • Humans
  • Male
  • Mice
  • Molecular Sequence Data
  • Mucopolysaccharidosis III / enzymology*
  • Mucopolysaccharidosis III / genetics*
  • Mutation*
  • Pedigree
  • Polymerase Chain Reaction
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Transfection


  • DNA, Complementary
  • Recombinant Fusion Proteins
  • Acetyltransferases
  • HGSNAT protein, human

Associated data

  • GENBANK/AK149883
  • GENBANK/DR000652
  • OMIM/252930
  • RefSeq/NT_007995
  • RefSeq/XM_372038
  • RefSeq/XP_341451
  • RefSeq/XP_519741
  • RefSeq/XP_539948
  • RefSeq/XP_588978