Hereditary multiple exostoses

Multiple cartilaginous exostoses is the name for an autosomal dominant inherited disorder characterized by numerous benign cartilage- capped bone tumors. Since it is osteochondromas, which are covered with hyaline cartilage instead of fibrocartilage, the term " cartilaginous " exostosis is actually incorrect. With an incidence of approximately 1:50,000 the Exostosenkrankheit among the most common bone tumor diseases, men and women are equally affected. In approximately 70% of patients there is a familial form, about 30 % have a sporadic form, ie a de novo mutation.

At birth, exostoses are still very rare, they occur mainly in childhood and youth, until the end of the growth plates. During this time take the exostosis to also in size. After the end of the growth form no further exostoses, and a later increase in size is then a sign of malignant transformation ( degeneracy ), ie Transformation into a malignant bone tumor. In about 3-5 % occurs on a secondary chondrosarcoma.

The Exostosenkrankheit can rarely be completely asymptomatic, the expression (phenotype ) but highly variable, even in a family. At about 19%, there are a maximum of five exostoses, at about 19%, there are more than twenty.

In general, the clinical problems are characterized by deformities and functional impairment, resulting in the clinical classification of severity by Pedrini into three classes and two sub-groups results:

Since the exostosis originating from the growth plates, they are often found near joints, where they cause movement restrictions, achsabweichendes growth with deformities and hypoplasia ( short stature ) of individual bones to general dwarfism. Typical deformities are differences in the length of the extremities, axis deviations in the knee and ankle joints, asymmetries in the area of ​​the shoulder and pelvic girdle, an ulnar deviation of the wrist with a curvature of the spoke and a subluxation of the radiocarpal joint to mention.

The exostoses may interfere but also in the immediate vicinity and compress nerves, blood vessels or tendons and thus trigger pain and motor problems.

Genetics

The Exostosenkrankheit is almost always based on a mutation of one of the two Egene EXT1 (65 %) or EXT2 (25 %). In general, the mutations in shortened and completely or partially non-functional EXT proteins lead. The two EXT proteins are ubiquitous transmembrane glycoproteins involved in the elongation of heparan sulfate glycosaminoglycan chains (HS- GAGs ), are involved in the matrix proteoglycans, in turn, in the context of cell growth and differentiation of cartilage cells play an important role play.

Treatment

Treatment depends on the disorder, and includes pain management, physiotherapy and surgical procedures for the removal of interfering exostoses and deformity. However, the results are not always satisfactory, in particular for multiple operations.

Synonyms

  • Ekchondrosis ossificans
  • Multiple osteochondromatosis
  • Multiple hereditary exostoses ( MHE )
  • Hereditary multiple exostoses (HME )
  • Exostosenkrankheit
  • Multiple osteochondromas
  • Exostotische dysplasia
  • Osteoplasia exostotica
  • Multiple Osteomatose
  • Dominant hereditary chondral osteoma
  • Multiple cartilaginous exostoses (English )
Dominance (genetics) Vertebral subluxation
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