What is osteogenesis imperfecta (OI)?

Osteogenesis imperfecta (OI) is a genetic disorder that affects the bones. This disease causes bones to be very weak and break with little or no trauma. OI is also known as brittle bone disease. People with OI also have weak muscles and bone deformities. In order to understand OI, it is important to know the different types. There are eight different types of OI. Each type has different signs and symptoms. There are four main types and four lesser-known types. Only the four main types will be discussed. The four lesser-known types only affect a total of 10 percent of people with OI.

What are the four main types of OI?

Type I

  • Least severe and most common
  • More fractures during childhood than adulthood
  • Some children may experience hearing loss

Type II

  • More severe
  • Underdeveloped bones at birth
  • Infants are born with soft skull bones

Type III

  • Very severe
  • Many infants are born with broken bones
  • Poor muscle development
  • Curved spine
  • Treatment needed throughout life

Type IV

  • Can range from mild to severe
  • Most children experience most fractures before puberty
  • Shorter than average
  • Bowed legs and curved spine

What causes OI?

The cause of this mutation (change in a gene) is unknown and needs to be researched further.

What are the symptoms of OI?

OI symptoms can range based on the severity of the disease. The most common symptoms are:

  • Weak muscles
  • Malformed bones
  • Loose joints
  • Blue or purple sclera (whites of the eyes)
  • Problems breathing
  • Brittle teeth
  • Triangular face
  • Bowed legs
  • Curved spine

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