Osteogenesis imperfecta (OI), commonly known as brittle bone disease, is a group of genetic bone disorders. People with OI do not produce enough good quality collagen to produce healthy, strong bones. Collagen is an important protein and without a good enough supply the bones are weak and break very easily.

As a genetic disorder, OI is a autosomal dominant defect. Most people with OI receive it from a parent but it can also be an individual (de novo or "sporadic") mutation.

Types

There are four types of OI, though the symptoms range from person to person. Type I is the most common and mildest form, followed by Type IV, Type III and Type II.

Type I

Collagen is normal but not of a high enough quantity:

• Bones fracture easily, especially before puberty
• Slight spinal curvature
• Loose joints
• Poor muscle tone
• Discolouration of the sclera (whites of the eyes)
• Early loss of hearing

Type II

Collagen is not of a sufficient quality or quantity

• Most cases die before adulthood
• Severe respiratory problems due to underdeveloped lungs
• Severe bone deformity and small stature

Type III

Collagen quantity is sufficient but is not of a high enough quality

• Bones fracture easily, sometimes even before birth
• Bone deformity, often severe
• Respiratory problems possible
• Short stature, spinal curvature and barrel-shaped rib cage
• Loose joints
• Poor muscle tone in arms and legs
• Discolouration of the sclera (whites of the eyes)
• Early loss of hearing

Type IV

Collagen quantity is sufficient but is not of a high enough quality

• Bones fracture easily, especially before puberty
• Short stature, spinal curvature and barrel-shaped rib cage
• Bone deformity is mild to moderate
• Discolouration of the sclera (whites of the eyes)
• Early loss of hearing

Treatment

There are no known cures for osteogenesis imperfecta, with the emphasis being on prevention of breakages. Those with OI are advised to exercise, maintain a positive diet and generally lead a healthy life.

One severe method of treatment is a procedure called rodding. This involves the insertion of metal rods through the length of the bone in order to strengthen them.

Links

• OI Foundation Inc. (USA)
• OI Federation Europe