Osteogenesis imperfecta

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Osteogenesis imperfecta is caused usually by defects in the COL1A1 gene at 17q21.31-q22 or COL1A2 at 7q21.3 . The phenotype varies and can often be caused by mutations in either gene in the autosomal dominant forms. This is the basis of Sillence's classification. Recessive forms have other genetic defects:
  1. Osteogenesis imperfecta type 1 (Type I)
    • Autosomal dominant
    • Multiple bone fractures (usually from minimal trauma)
    • Blue sclerae
    • Normal teeth
    • Normal or near-normal stature
  2. Osteogenesis imperfecta type 2A (for 2B see type 6) (Type II)
    • Autosomal dominant
    • Perinatal fractures
    • Severe bowing long bones
    • Undermineralization
    • Death
  3. Osteogenesis imperfecta type 3 (Type III)
  4. Osteogenesis imperfecta type 4 (Type IV) (see also type 12)
  5. Osteogenesis imperfecta type 5 (cause unknown) (Type V)
    • Autosomal recessive (apparently)
    • Moderately deforming
    • Bone fragility
    • Normal sclera
    • Teeth normal
    • Hyperplastic callus formation at fracture sites
    • Calcification of the interosseous membrane between the radius and ulna
    • Radioopaque metaphyseal band adjacent to the growth plates
  6. Osteogenesis imperfecta type 6 (Type VI)
    • Caused by mutations of FKBP10 gene at 17q21
    • Autosomal recessive
    • Fractures as early infant
    • Short stature
    • Scoliosis
    • Minimal blue sclerae
  7. Osteogenesis imperfecta type 7 (Type VII)
    • Caused by mutations of CRTAP gene at 3p22.3
    • Autosomal recessive
  8. Osteogenesis imperfecta type 8 (Type VIII)
    • Caused by mutations of LEPRE1 gene at 1p34.2
    • Autosomal recessive
    • White sclerae
    • Very short stature
    • Extreme skeletal undermineralization
    • Bulbous metaphyses
  9. Osteogenesis imperfecta type 9 (Type IX)
    • Caused by mutations of PPIB gene at 15q22.31
    • Autosomal recessive
    • Severe - many affected fetuses abort
  10. Osteogenesis imperfecta type 10 (Type X)
  11. Osteogenesis imperfecta type 11 (Type XI)
    • Caused by mutations of SP7 gene at 12q13.13
    • Autosomal recessive
    • Recurrent fractures and mild deformities
    • Generalized osteopenia
    • Delayed teeth eruption but normal teeth
    • White sclerae
  12. Osteogenesis imperfecta type 12 (Type XII)
    • Caused by mutations of SERPINF1 gene at 17p13.3[1]
    • Autosomal recessive
    • Type 4 phenotype

References

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