multiple hereditary exostosis

Pathology

• multiple projections of bone capped by cartilage
  • most numerous in metaphyses of long bones
  • also diaphyses of long bones, flat bones, vertebrae, ribs
  • skull generally not involved
• deformity of the legs, forearms & hands is frequent

Genetics

• autosomal dominant
• type 1 caused by mutation in the exostosis 1 gene
• type 2 caused by mutation in the exostosis 2 gene

Differential diagnosis

• metachondromatosis (156250)
• Langer-Giedion syndrome (trichorhinophalangeal syndrome type 2) (150230)
• fibrodysplasia ossificans progressiva (135100)
• occipital horn syndrome (304150)
• adult stage of hereditary hypophosphatemia (307800)

More general terms

• exostosis; hyperostosis; osteoma; osteoncus
• skeletal dysplasia

Additional terms

• exostosin-1; glucuronosyl-N-acetylglucosaminyl-proteoglycan/N-acetylglucosaminyl-proteoglycan 4-alpha-N-acetylglucosaminyltransferase; tumor suppressor protein EXT1; multiple exostoses protein 1 (EXT1)
• exostosin-2; glucuronosyl-N-acetylglucosaminyl-proteoglycan/N-acetylglucosaminyl-proteoglycan 4-alpha-N-acetylglucosaminyltransferase; tumor suppressor protein EXT2; multiple exostoses protein 2 (EXT2)

Database

• OMIM: https://mirror.omim.org/entry/133700