title: Multiple osteochondromas: mutation update and description of the multiple osteochondromas mutation database (MOdb).
abstract: Multiple osteochondromas (MO) is an autosomal dominant skeletal disease characterized by the formation of multiple cartilage-capped bone tumors growing outward from the metaphyses of long tubular bones. MO is genetically heterogeneous, and is associated with mutations in Exostosin-1 (EXT1) or Exostosin-2 (EXT2), both tumor-suppressor genes of the EXT gene family. All members of this multigene family encode glycosyltransferases involved in the adhesion and/or polymerization of heparin sulfate (HS) chains at HS proteoglycans (HSPGs). HSPGs have been shown to play a role in the diffusion of Ihh, thereby regulating chondrocyte proliferation and differentiation. EXT1 is located at 8q24.11-q24.13, and comprises 11 exons, whereas the 16 exon EXT2 is located at 11p12-p11. To date, an EXT1 or EXT2 mutation is detected in 70-95% of affected individuals. EXT1 mutations are detected in +/-65% of cases, versus +/-35% EXT2 mutations in MO patient cohorts. Inactivating mutations (nonsense, frame shift, and splice-site mutations) represent the majority of MO causing mutations (75-80%). In this article, the clinical aspects and molecular genetics of EXT1 and EXT2 are reviewed together with 895 variants in MO patients. An overview of the reported variants is provided by the online Multiple Osteochondromas Mutation Database (http://medgen.ua.ac.be/LOVD).
authors.affiliation: Department of Medical Genetics, University and University Hospital of Antwerp, Antwerp, Belgium.
authors.forename: Ivy
authors.initials: I
authors.lastname: Jennes
authors.forename: Elena
authors.initials: E
authors.lastname: Pedrini
authors.forename: Monia
authors.initials: M
authors.lastname: Zuntini
authors.forename: Marina
authors.initials: M
authors.lastname: Mordenti
authors.forename: Sahila
authors.initials: S
authors.lastname: Balkassmi
authors.forename: Carla G
authors.initials: CG
authors.lastname: Asteggiano
authors.forename: Brett
authors.initials: B
authors.lastname: Casey
authors.forename: Bert
authors.initials: B
authors.lastname: Bakker
authors.forename: Luca
authors.initials: L
authors.lastname: Sangiorgi
authors.forename: Wim
authors.initials: W
authors.lastname: Wuyts
mesh_terms: D000818:Animals; D030541:Databases, Genetic; D004195:Disease Models, Animal; D005097:Exostoses, Multiple Hereditary / Q000175:diagnosis / Q000235:genetics*; D006801:Humans; D009154:Mutation / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics