What Is Osteogenesis Imperfecta (OI)?

Osteogenesis imperfecta is a group of rare congenital genetic disorders characterized by fragile bone structure. Individuals with this condition have bones that fracture easily, often without an obvious cause or following only minor trauma. Osteogenesis imperfecta is also known as brittle bone disease or “porcelain doll disease.” The severity of the condition varies widely: some individuals experience only a small number of fractures, while others may develop multiple complications. The disorder is present before birth and is not caused by injury, malnutrition, or inadequate care after birth.

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Based on the extent of bone involvement and clinical presentation, osteogenesis imperfecta is classified into several types, ranging from milder forms with relatively few fractures to more severe forms marked by frequent fractures and pronounced skeletal deformities. Considerable variation exists among individuals, which is one of the defining features of this condition.

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Why Do Bones Become So Fragile?

Healthy bones are not simply rigid structures but tissues that combine strength with flexibility. This flexibility is largely provided by collagen, which gives bones their toughness and allows them to absorb and distribute mechanical stress rather than breaking under pressure. In individuals with osteogenesis imperfecta, mutations in genes responsible for collagen production, such as COL1A1 and COL1A2, lead to insufficient collagen production or abnormal collagen structure (Figures 1 and 2). As a result, bones may appear intact but lack adequate support and shock-absorbing capacity, making fractures likely during everyday activities or after even minor external forces.

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How Does the Disease Gradually Manifest?

The effects of osteogenesis imperfecta often become apparent early in life. While anyone can develop osteogenesis imperfecta, individuals with a family history are more likely to be affected due to inherited genetic abnormalities, which may come from one or both parents. Genetic counselors can help families better understand the inheritance patterns of osteogenesis imperfecta. Some children experience fractures at birth or during infancy, while others are diagnosed later, when increased physical activity—such as rolling over, standing, or walking—makes fractures more noticeable. As affected individuals grow older, repeated fractures may interfere with normal bone development, leading to short stature and curvature of the limbs or spine. Some patients may also develop brittle teeth, hearing loss, or joint laxity. It is important to note that disease severity does not necessarily worsen in a linear manner with age, and individuals with milder forms may experience relatively stable symptoms over time.

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How Does This Condition Affect Daily Life?

Although osteogenesis imperfecta primarily affects the bones, its impact often extends to many aspects of daily life. Recurrent fractures can cause pain and limit mobility, while skeletal deformities may alter gait and increase physical strain. Long-term medical follow-up and rehabilitation therapy frequently become integral parts of life. All individuals with osteogenesis imperfecta have fragile bones, but the degree of fragility varies widely. Some people may experience only a few fractures over their lifetime, while others may sustain hundreds, including fractures that occur before birth.

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In addition to bone fragility, individuals with osteogenesis imperfecta may experience a range of other symptoms, the severity of which differs from person to person. These may include deformities or bowing of long bones, short stature, skin that bruises easily, loose joints, muscle weakness, and sclera that appear blue, purple, or gray. Some individuals may have a triangular-shaped face, barrel-shaped rib cage, spinal curvature, or compression and collapse of vertebrae. Dental abnormalities such as fragile, misshapen, or discolored teeth and misaligned bite may also occur. Hearing loss, breathing difficulties, hip deformities, downward angulation of the femoral neck (a condition known as coxa vara), and joint contractures—where joints become permanently fixed in a bent or straightened position—can further affect quality of life.​