A Family Guide to Non-Oncologic Blood Disorders
Osteogenesis Imperfecta
What is osteogenesis imperfecta? Osteogenesis imperfecta (OI) is an inherited disorder that is characterized by weak or fragile bones that fracture (or break) for no specific reason or cause. Your child with OI also may have weak muscles, brittle teeth, and hearing loss. OI is some- times called “brittle bone” disease. What are causes of OI? Type I collagen is a major component of the connective tissues in bones and is important in forming ligaments, teeth, and sclera (the white outer tissue of the eyeballs). In OI there is a defective gene that is unable to tell the body to make a specific protein. As a result of the defective gene, the body cannot make enough type I collagen, or the body makes enough but it is of poor quality. The bones are fragile and can break easily. In most cases of OI, children will inherit the defective gene from one of their parents. However, in some cases, neither par- ent has OI and the genetic defect is a spontaneous mutation (change) in the gene. This means it stops functioning correctly. What are some symptoms of OI? The following are the most common symptoms of OI. However, each child may experience symptoms differently. Symptoms vary based on the type of OI diagnosed and may include: • Bones fracture easily
• Symptoms include:
» » Little or no bone deformity, but bones are easily broken » » Teeth prone to cavities and cracking » » Blue, purple, or gray tint to the sclera of the eyes
Type II • Most severe form of the disease • Symptoms include:
» » Infants often born with small chest and soft skull » » Legs often in the frog-leg position » » Characteristic radiologic features such as flat vertebral body and very short telescoped, broad femurs » » Low birth weight » » Dark blue or grey sclerae
Type III • Most severe form of the disease • Symptoms include: » » Severe bone deformities
» » Infants often born with fractures » » Blue, purple, or gray tint to the sclera of the eyes » » Generally shorter than average » » Spinal deformities » » Respiratory complications » » Brittle teeth
• Blue, purple, or gray color to the sclera • Dental problems (brit- tle teeth) • Hearing loss beginning around ages 20 to 30 • Triangular shaped face • Spinal curvature
• Bone deformities • Muscle weakness • Improperly formed collagen • Loose joints • Short, small body
Type IV • Moderately severe • Symptoms include:
» » Mild to moderate bone deformities » » Bones fracture easily » » Normal sclera of the eyes (white in color) » » May be shorter than average » » May have brittle teeth
What are the types of OI? Type I • Most common and mildest type of this disease
Osteogenesis Imprefecta
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