What is OI ?

What is Osteogenesis Imperfecta (OI)?

Osteogenesis Imperfecta (OI) or Brittle Bone Disease is a genetic disorder that makes the bones of an individual break easily with little trauma or without any apparent reason.

The term Osteogensis imperfect simply means Imperfect Bone Formation.

The major cause of OI is when there is a mutation (change) in a gene that affects the bone formation, bone strength and the structure of other tissues in an individual. Both male and females in all racial groups can be affected with this condition and the severity ranges from mild, moderate to severe.

Usually bones of OI individuals experience frequent breaks during infancy through to puberty and decrease as the individual grows to adulthood.

Currently it has no cure but with good medical management and supportive mechanisms individuals with OI live healthy productive lives.

General Symptoms

Signs and symptoms of the most common forms of OI can be present at birth, or later in childhood.
This includes:

  • Bone deformity,
  • Easily fractured bones
  • Short stature.
  • Blue Sclera (ie blue pigments on the normal white area of the eyeball)
  • Spinal curvature
  • Triangular –shaped face
  • Low Bone Density.
  • Loose joints, ligament laxity and muscle weakness are common.
  • Hearing loss
  • Brittle teeth (called dentinogenesis imperfecta or DI) are seen in 50% of people who have OI
    Respiratory issues.

How is OI Diagnosed?

OI can be diagnosed by

  • Physical examination
  • X-rays
  • Ultra Scans (prenatally)
  • Genetic testing

How is OI Treated?

There is no cure for OI, but there are ways to manage the symptoms to minimize fractures, bone pain and promote good health

Fracture Care. Fracture Care includes casting, splinting and bracing broken bones can help them heal properly and reduce pain.

Physical Therapy and Safe Exercise. Physical therapy is basically needed to increase muscle strength and increase mobility of an OI individual.it is very ideal to begin this therapy in infancy to help counteract the delay in motor skill development many children experience due to OI related muscle weakness. Adaptive devices may be needed. Swimming and water therapy are known to be an effective way to increase muscle strength and particularly well-suited for people with OI of all ages, as they allow independent movement with little fracture risk.

Surgery. Surgery is mainly used to correct bone deformities such as bowing in OI. Surgical procedure known as rodding (metal rods insertion) into the long bones are used to control fractures and improve deformities that interfere with function. Both non-expandable and expandable rods are available.

Medications. Bisphosphonate drugs, is currently used to increase bone density in children and adults with moderate and severe OI is specific for OI. This medication is however proven to help reduce bone fractures and pain.

Healthy Nutrition. Healthy balanced diet is very important in the general health of an OI individual. Adequate intake of nutrients, such as Vitamin D and calcium is necessary to maintain bone health. Bad habit such as smoking, excessive alcohol and Caffeine should be avoided by OI individuals since it reduces bone density. Obesity and overweight should also not be encouraged in OI since it attributes to health issues.

Other Treatments that focus on OI related symptoms include:

  • The use of Hearing aids
  • Crowning the teeth of dentinogenesis imperfecta cases.
  • The use of Mobility aids such as walkers, crutches, canes and wheelchairs

How Is OI Inherited?

Osteogenesis imperfecta (OI) is a genetic disorder. Most cases (90 percent) are caused by a faulty gene that reduces either the amount or the quality of type 1 collagen throughout the body. These mutations are inherited in a dominant manner. The other 10 percent of cases are caused by mutations in other genes that are inherited in either a dominant or a recessive manner.

Types of OI

Type I

  • Most common and mildest type of OI.
  • Bones fracture easily. Most fractures occur before puberty.
  • Normal or near-normal stature.
  • Loose joints and muscle weakness.
  • Sclera (whites of the eyes) usually have a blue, purple, or gray tint.
  • Triangular face.
  • Tendency toward spinal curvature.
  • Bone deformity absent or minimal.
  • Brittle teeth possible.
  • Hearing loss possible, often beginning in early 20s or 30s.
  • Collagen structure is normal, but the amount is less than normal.

Type II

  • Most severe form.
  • Frequently lethal at or shortly after birth, often due to respiratory problems. 
  • Numerous fractures and severe bone deformity.
  • Small stature with underdeveloped lungs.
  • Tinted sclera.
  • Collagen improperly formed.

Type III

  • Bones fracture easily. Fractures often present at birth, and x-rays may reveal healed fractures that occurred before birth.
  • Short stature.
  • Sclera have a blue, purple, or gray tint.
  • Loose joints and poor muscle development in arms and legs.
  • Barrel-shaped rib cage.
  • Triangular face. 
  • Spinal curvature.
  • Respiratory problems possible.
  • Bone deformity, often severe.
  • Brittle teeth possible.
  • Hearing loss possible.
  • Collagen improperly formed.

Type IV

  • Between Type I and Type III in severity.
  • Bones fracture easily. Most fractures occur before puberty.
  • Shorter than average stature.
  • Sclera are white or near-white (i.e. normal in color).
  • Mild to moderate bone deformity.
  • Tendency toward spinal curvature.
  • Barrel-shaped rib cage.
  • Triangular face.
  • Brittle teeth possible.
  • Hearing loss possible.
  • Collagen improperly formed

Type V

  • Clinically similar to Type IV in appearance and symptoms of OI.
  • A dense band seen on x-rays adjacent to the growth plate of the long bones.
  • Unusually large calluses (hypertrophic calluses) at the sites of fractures or surgical procedures. (A callus is an area of new bone that is laid down at the fracture site as part of the healing process.)
  • Calcification of the membrane between the radius and ulna (the bones of the forearm). This leads to restriction of forearm rotation. 
  • White sclera.
  • Normal teeth. 
  • Bone has a “mesh-like” appearance when viewed under the microscope. 
  • Dominant inheritance pattern

Type VI

  • Clinically similar to Type IV in appearance and symptoms of OI.
  • The alkaline phosphatase (an enzyme linked to bone formation) activity level is slightly elevated in OI Type VI. This can be determined by a blood test. 
  • Bone has a distinctive “fish-scale” appearance when viewed under the microscope.
  • Diagnosed by bone biopsy.
  • Whether this form is inherited in a dominant or recessive manner is unknown, but researchers believe the mode of inheritance is most likely recessive.
  • Eight people with this type of OI have been identified.

Recessive Forms of OI
Researchers have identified two forms of OI that are inherited in a recessive manner.

Type VII

  • Sometimes symptoms of this type are similar to Type IV OI in many aspects of appearance and symptoms.

Type VIII

  • Similar to l Type II or Type III OI in appearance and symptoms Normal white sclera.

Suggested OI support organization websites for more information includes:

http://www.cbbf.org

http://www.oif.org

http://www.brittlebone.org

http://www.oifnigeria.org

http://www.oife/en/