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Home > E. Pathology by systems > Locomotory system > Bones > achondrogeneses


Friday 5 January 2007


- extreme disorganization and retardation of the physeal growth zone

- in achondrogenesis type 1A (IA), resting chondrocytes frequently contain characteristic large PAS-positive, diastase resistant cytoplasmic inclusions (spherical or oval, lying within membrane-bound vacuoles) (chondrocytic inclusions)

- in achondrogenesis type 1B (IB), resting cartilage is characterized by matrix deficiency and perichondrocytic collagen rings which stain trichrome, silver methenamine and toluidine blue. Chondrocytic inclusions are absent.

- in achondrogenesis type 2,

  • generalized deficiency of the matrix
  • increased number of markedly enlarged lacunae and chondrocytes that may have abundant clear cytoplasm
  • cartilage canals are markedly enlarged, stellate in shape and fibrotic
  • the physeal growth zone is markedly retarded and disorganized with closely arranged large chondrocytic lacunae and prominently deficient intervening matrix
  • predominant collagen is type 1 rather than type 2 (disorder of type 2 collagen biosynthesis by COL2A1 germline mutations)


- achondrogenesis type 1 (AGC1s)

  • achondrogenesis type 1A (AGC1A) (MIM.200600)
  • achondrogenesis type 1B (AGC1B) (SLC26A2 at 5q32-q33.1) (MIM.600972)

- achondrogenesis type 2 (AGC2) (COL2A1 at 12q13.11-q13.2) (MIM.200610)
- achondrogenesis type 3 (AGC3) (MIM.200710)
- achondrogenesis type 4 (AGC4) (MIM.200720)

Case records

- Case 10610: Achondrogenesis type 2

See also

- osteochondrodysplasias