What Is Osteogenesis Imperfecta?
Osteogenesis imperfecta (OI) is a genetic disorder characterized by bones that break easily, often from little or no apparent trauma. OI is highly variable, and signs and symptoms range from mild to severe. In addition to broken bones, people with OI sometimes have muscle weakness or joint laxity (loose joints), and they often have skeletal malformations including short stature, scoliosis (curvature of the spine), and bowing of long bones. A classification system featuring different types of OI is commonly used to help describe how severely a person with OI is affected. OI occurs with equal frequency in males and females and among all ethnic and racial groups.
OI is caused by genetic defects that affect the body’s production of type I collagen. Collagen is the major protein of the body’s connective tissue and can be likened to the framework around which a building is constructed. In dominant (classical) OI, a person has too little type I collagen or a poor quality of type I collagen due to a mutation in one of the type I collagen genes. In recessive OI, mutations in other genes interfere with collagen production. The result in all cases is weak bones that break easily.
What Is Osteoporosis?
Osteoporosis is a condition in which the bones become less dense and more likely to break. Fractures (broken bones) from osteoporosis can result in significant pain and disability. It is a major health threat for an estimated 44 million Americans, 68 percent of whom are women.
Risk factors for developing osteoporosis include:
- thinness or small frame
- family history of the disease
- being postmenopausal and particularly having had early menopause
- abnormal absence of menstrual periods (amenorrhea)
- prolonged use of certain medications, such as those used to treat lupus, asthma, thyroid deficiencies, and seizures
- low calcium intake
- lack of physical activity
- excessive alcohol intake.
Osteoporosis is a silent disease until a fracture occurs. Osteoporosis can often be prevented. However, if undetected, it can worsen over many years without symptoms. It has been called "a pediatric disease with geriatric consequences," because building healthy bones in one's youth is important to help prevent osteoporosis and broken bones later in life.
The Link Between OI and Osteoporosis
The term osteoporosis describes bone loss that is extensive enough to increase the risk of fracture. The term is a general one, not related to any specific cause for the bone loss. In fact, there are many causes of osteoporosis. Nearly all people with OI have osteoporosis, because they do not develop appropriate bone mass at any age. Women and men with OI can experience additional bone loss, such as age-related bone loss, superimposed on a background of OI. Symptoms of additional bone loss may appear at a younger age than commonly seen in people who do not have OI. When women and men with OI reach middle-age, their risk of breaking bones more easily increases even further. Factors such as a diet low in calcium and vitamin D, smoking, decreased activity, and decreased levels of protective sex hormones (e.g., testosterone, estrogen) can compromise bone density and lead to a return to the fracture cycles they experienced as children.