A rare genetic condition known as osteogenesis imperfecta (OI) affects collagen production and quality, a protein essential for bones, skin, ligaments, and other tissues. It is common for people with OI to have weak, brittle bones, which are easily broken by minor trauma or even without apparent cause. Other problems can also be caused by OI, including hearing loss, dental issues, scoliosis, and short stature. Depending on the genetic mutation type and severity, OI can range from mild to severe. There are at least eight types of OI, categorized by Roman numerals from I to VIII. Type I is the most common and mildest form, while type II is the most severe and often fatal in young children. The most severe form of OI is OI type III. Type IV is the most common moderate form. Types V to VIII are rare and have variable features and severity.
Causes
Mutations in the collagen genes or the proteins that interact with collagen cause OI to occur. In addition to supporting the structure and function of bones and other organs, collagen is the main component of connective tissue. A mutation in collagen genes can make collagen weak and fragile, affecting its quantity, quality, or structure. OI is inherited in an autosomal dominant pattern, so one mutated gene from either parent is sufficient to cause the disease. In some cases of OI, the disorder is inherited from both parents in a recessive pattern, meaning both copies of the mutated gene are required. When a new or spontaneous mutation occurs in egg or sperm cells, or during early development, it causes some cases of OI.
Symptoms
The symptoms of OI vary widely depending on the type and severity of the disorder. The main symptom of OI is bone fragility, which leads to frequent and multiple fractures, often with minimal or no trauma. In addition to the arms and legs, ribs, spine, and skull, fractures are more common in the body. They cause pain, swelling, bruising, deformity, and reduced mobility. Additionally, fractures may result in short stature, scoliosis, or limb deformities. Other symptoms of OI include:
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Sclerae (the whites of the eyes) can be blue, gray, or brown
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Adults are more likely to experience hearing loss than children
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A weak enamel, decayed teeth, or malocclusion are examples of dental problems
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Joint pain or loose joints
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Bruised or torn skin
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Asthma, pneumonia, or sleep apnea are all respiratory problems
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Aortic aneurysm, mitral valve prolapse, or heart failure are all cardiac problems
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Problems with the nervous system, such as hydrocephalus, basilar invagination, or Chiari malformation
Diagnosis
The doctor will ask about the symptoms, the medical history, and the family history of the patient. He will also perform a physical examination, which will include:
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Checking the skin, eyes, and teeth for signs of OI
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Examining the bones and joints for fractures or deformities
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The patient's height and weight should be measured
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Hearing and vision tests are performed on the patient
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Analyzing the patient's respiratory and cardiac functions
To confirm the diagnosis and determine the type and severity of OI, the doctor may also order the following tests:
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In X-rays, the bone structure and fractures or deformities can be seen
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Using a bone density scan, you can determine your bone mineral density and fracture risk
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Under a microscope, bone biopsy can examine the collagen structure and bone tissue
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A genetic test can identify the specific gene mutation that causes OI
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A prenatal test that involves amniocentesis or chorionic villus sampling to diagnose OI in the fetus
Treatment
OI cannot be cured, but treatment can manage the symptoms, prevent or reduce complications, and improve quality of life. The treatment may include:
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Bone-building medications, such as bisphosphonates, growth hormone, or teriparatide, can increase bone density and strength and reduce fracture risk
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Medications that relieve pain and inflammation caused by fractures or other problems, such as acetaminophen, ibuprofen, or opioids
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Infections of the respiratory tract or urinary tract can be treated or prevented with antibiotics
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Tinnitus or hearing loss can be treated with hearing aids
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Preventing and treating dental problems, such as tooth decay, gum disease, and malocclusions
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In surgery, the bones and joints can be repaired or stabilized, deformities can be corrected, or devices can be implanted to support them, such as rods, plates, screws, or pins.
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Patients can benefit from physical therapy by improving their mobility, balance, posture, and muscle strength, as well as by preventing or reducing contractures or stiffness of the joints.
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As well as improving daily living skills, independence, and self-esteem, occupational therapy can provide the patient with adaptive equipment or assistive devices to help him or her move or function, like braces, splints, crutches, or wheelchairs.
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Counseling can help cope with emotional, social, or behavioral issues, such as depression, anxiety, stress, or low self-confidence, that can result from OI
Prevention
While OI cannot always be prevented, there are some measures that can be taken to reduce the risk or severity of the condition, such as:
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A genetic counselor can provide information and guidance about inheritance, recurrence, testing, and management of OI, enabling patients and their families to make informed decisions about their reproductive options.
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A prenatal screening can detect OI in a fetus by ultrasound, blood test, or genetic test, and help the parents prepare for the birth or treatment.
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Injury to the bones should be avoided, especially during growth or development
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Treatment and follow-up of OI according to the doctor's instructions and recommendations
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To support bone health and growth, eat a balanced diet rich in calcium and vitamin D
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Under the supervision of a physical therapist or doctor, regular exercise strengthens bones and muscles and improves joint function
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Preventing falls or accidents by using safety equipment, avoiding slippery surfaces, or removing obstacles
