The severity of this type of Osteogenesis Imperfecta falls between Type I and Type III. It is inherited in an autosomal dominant manner, although it can also result from a spontaneous mutation. Type IV Osteogenesis Imperfecta is moderately severe, with improperly formed collagen. Bones fracture easily, but the whites of the eyes are normal. Some people with type IV Osteogenesis Imperfecta may be shorter than average and may have brittle teeth. Bone deformities are mild to moderate.

Type IV Osteogenesis Imperfecta is not as severe as type III, but is worse than type I. Approximately one in every twenty thousand have this form of the disease. Their collagen is improperly formed and their bones are brittle. Fractures are most common in OI Type IV before puberty. The exception to this is in women, who after menopause experience resurgence in the number of fractures.

The degree of bone deformity in their spines and legs prevent them from walking and require them to use a wheelchair. They have a barrel shaped rib cage because their organs are the same size as they would be if they didn't have the diseases. Because the organs are all squished within the small body, there are a number of problems that can occur, such as asthma, bowel issues, acid reflux disease, and many more.

Typical characteristics of Osteogenesis Imperfecta Type IV include ...

• Between Type I and Type III in severity.

• This type of OI is not clearly defined.

• Autosomal dominant.

• Short stature.

• Abnormal collagen.

• Below average height.

• Scoliosis.

• Mild to moderate bone deformity.

• Triangular face.

• Barrel-shaped ribcage.

• Little tendency to develop hearing loss

• Possible brittle teeth.

• Loose, easily overstretched joints.

• Bones fracture easily. Most fractures occur before puberty. Fractures usually begin in infancy, but in utero fractures may occur.

• Sclera is white or near-white (i.e. normal in color).

• Tendency toward spinal curvature.

• Femoral bowing, only a mild bone deformity.

Other Types ...

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 that groups had other features in common.

They named these groups Types V and 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 I collagen genes.