Genomic organization of the human phosphomannose isomerase (MPI) gene and mutation analysis in patients with congenital disorders of glycosylation type Ib (CDG-Ib)

Hum Mutat. 2000 Sep;16(3):247-52. doi: 10.1002/1098-1004(200009)16:3<247::AID-HUMU7>3.0.CO;2-A.


CDG-Ib is the "gastro-intestinal" type of the congenital disorders of glycosylation (CDG) and a potentially treatable disorder. It has been described in patients presenting with congenital hepatic fibrosis and protein losing enteropathy. The symptoms result from hypoglycosylation of serum- and other glycoproteins. CDG-Ib is caused by a deficiency of mannose-6-phosphate isomerase (synonym: phosphomannose isomerase, EC, due to mutations in the MPI gene. We determined the genomic structure of the MPI gene in order to simplify mutation detection. The gene is composed of 8 exons and spans only 5 kb. Eight (7 novel) different mutations were found in seven patients with a confirmed phosphomannose isomerase deficiency, analyzed in the context of this study: six missense mutations, a splice mutation and one insertion. In the last, the mutation resulted in an unstable transcript, and was hardly detectable at the mRNA level. This emphasizes the importance of mutation analysis at the genomic DNA level.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Congenital Disorders of Glycosylation / enzymology*
  • Congenital Disorders of Glycosylation / genetics*
  • DNA Mutational Analysis
  • Exons*
  • Glycosylation
  • Humans
  • Introns*
  • Mannose-6-Phosphate Isomerase / chemistry
  • Mannose-6-Phosphate Isomerase / deficiency*
  • Mannose-6-Phosphate Isomerase / genetics*
  • Molecular Sequence Data
  • Mutation, Missense


  • Mannose-6-Phosphate Isomerase

Associated data

  • GENBANK/AF227216
  • GENBANK/AF227217
  • GENBANK/AF227218