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What are the types of Osteogenesis Imperfecta?

By  ,  National Institute of Health
Jan 06, 2013
4.8 / 5(4 Ratings)

Type I OI

  • most common and mildest type of OI
  • bones predisposed to fracture (most fractures occur before puberty)
  • normal or near-normal stature
  • loose joints and muscle weakness
  • blue, purple, or gray tint to sclera (whites of the eyes)
  • triangular face
  • tendency toward spinal curvature
  • absent or minimal bone deformity
  • possible brittle teeth
  • possible hearing loss, often beginning in early twenties or thirties
  • normal collagen structure, but less than normal amount

Type II OI

  • most severe form of OI
  • frequently causes death at birth or shortly after, because of respiratory problems
  • numerous fractures and severe bone deformity
  • small stature with underdeveloped lungs
  • blue, purple, or gray tinted sclera
  • improperly formed collagen

Type III OI

  • easily fractured bones (Fractures often present at birth, and x rays may reveal healed fractures that occurred before birth.)
  • small stature
  • blue, purple, or gray tinted sclera
  • loose joints and poor muscle development in arms and legs
  • barrel-shaped rib cage
  • triangular face
  • spinal curvature
  • possible respiratory problems
  • often severe bone deformity
  • possible brittle teeth
  • possible hearing loss
  • improperly formed collagen

Type IV OI

  • between Type I and Type III OI in severity
  • bones easily fractured (most fractures occur before puberty)
  • smaller than average stature
  • sclera normal in color (i.e., white or near-white)
  • mild to moderate bone deformity
  • tendency toward spinal curvature
  • barrel-shaped rib cage
  • triangular face
  • possible brittle teeth
  • possible hearing loss
  • improperly formed collagen
  • By studying the appearance of OI bone under the microscope, investigators noticed that some people who are clinically within the Type IV group had a distinct pattern to their bone. When they reviewed the full medical history of these people, they found the groups had other features in common. They named these groups Type V and Type VI OI. The mutations causing these forms of OI have not been identified, but people in these two groups do not have mutations in the type 1 collagen genes.

Type VI OI

  • clinically similar to Type IV OI in appearance and symptoms
  • slightly elevated activity level of alkaline phosphatase (an enzyme linked to bone formation), which can be determined by a blood test
  • distinctive “fish-scale” appearance to bone when viewed under the microscope
  • diagnosed by bone biopsy
  • unknown whether this form is inherited in a dominant or recessive manner, but researchers believe the mode of inheritance is most likely recessive
  • eight people identified with this type of OI to date

 

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