Brittle bone disease – osteogenesis imperfecta

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Osteogenesis imperfecta also known as brittle bone disease is a disease that causes an abnormality in the production of a protein called collagen.

Collagen is an important protein that supports the body, or, more exactly, the frame on that the body is built. There are several types of collagen, but the one that is found in highest amount in the body called collagen type I.

Type I collagen is found in bones, eye sclera, ligaments and teeth. Osteogenesis imperfecta occurs when there is a deficiency in collagen type I.


1. Overview
2. Causes
3. Symptoms
4. Treatment


- Abnormal collagen rods – Experts explain that rods alter abnormal bone collagen elasticity bone structure. In osteogenesis imperfecta they are different sizes and we can found them in smaller quantities.

A defect in the collagen molecules structure causes a mutation in the DNA of genes that create collagen. Mutation produces abnormal deformed collagen and abnormal collagen fibers. Bones are not solid because abnormal collagen fibers affect and consume any healthy collagen fibers.

The process is cyclic in a child growing and prevents new and healthy bone. The result is increased risk of fractures and fracture during youth. However, this process will improve at puberty when the bone growth process slows down.

- Genetics – Scientists believe that most types of osteogenesis imperfecta result from an inherited autosomal dominant pattern. This means that if a child is born to a mother, who presents a dominant mutation, 50% are likely to be transmitted to the baby. However, it seems that about 15% of children have inherited osteogenesis imperfecta as a result of recessive mutations.

In essence, recessive mutation occurs when both parents carry the recessive gene for the disease but show no disorder. Probability of carrying the recessive gene and pass it on heirs is 100%, but this does not mean that the disorder will manifest itself in future generations.

- Other factors – a major cause of brittle bone disease is the osteoblasts that are affected by the collagen molecules. Osteoblasts are cells responsible for bone formation. Because of poor quality of collagen fibers that have a negative impact on osteoblasts, new bone cells can’t form and divide properly.


Since collagen is a fibrous protein found in bones, cartilage, tendons and other connective tissues, most fragile bone disease symptoms occurs in the bones and joints.

1. Fractures – The bones are complex structures consisting of proteins, minerals and living cells. Skeleton is composed of protein collagen rods tied together to form strong fibers. The minerals are then deposited on this strong foundation. For patients with osteogenesis imperfecta, or the body don’t produces enough collagen or that that is produced is abnormal. Therefore, collagen rods are weak and deformed. The bones that contain them break easily, especially for children whose bones are growing rapidly.

2. Joint laxity – Laxity is characterized by instability of joint that connect two bones. Joints consist of two bones that are covered by cartilage, tendons and ligaments, which hold the bones together and are composed of collagen. Abnormal collagen present in patients with osteogenesis cause a malfunction of the ligaments, cartilage and tendons, resulting in joint laxity.

3. Blue sclera eye – Eye sclera is a fibrous membrane that, with cornea, covers the eyes and provides protection. The part of sclera, which is easily seen, is called the sclera eye or eye’s white. It contains collagen. Because dysfunction of collagen products, those diagnosed with brittle bone disease type I have a sclera thinner than normal. This allows visualization of veins in the eye, which offers sclera the blue color.

4. Hearing loss – Approximately 50% of those who have brittle bones experiences hearing loss too. Ability to hear sound waves supposed to be translated by the three small bones of the middle ear. If a one of these bones is fractured, hearing loss can occur.

5. Chronic pain – This is a symptom seen in many adults with fragile bones. Pain, often located in the lower back or hips may be due to old fractures or compression fractures in the spine. Predominant and joint pain may be already affected by disease as they grow old.


Currently, there is no known cure for osteogenesis imperfecta. The main goal of treatment should be to prevent accidents and maintain bone health. In children with osteogenesis imperfecta should be provided a diet with nutrients. They need to exercise regularly and maintain a healthy weight. Often children with osteogenesis imperfecta will need splints, wheelchair or ambulatory aid.

Surgical treatment of osteogenesis imperfecta conditions depends on the severity and patient age. Most fractures of the very young children are treated as if the child has no underlying condition. However, surgical stabilization of fractures is quite common even at young ages.

Fractures in children with osteogenesis imperfecta are often treated with surgery to stabilize bone and to prevent deformation. One of the procedures used is one that involves inserting a metal rod in the center hollow bone to support the fragile bones and prevent bone deformity.

Scoliosis is treated aggressively because the problem tends to progress in children with osteogenesis imperfecta. The role of drugs in the treatment of osteogenesis imperfecta is increasingly appreciated, and recent studies have demonstrated the benefits of treatment with bisphosphonates, especially calcium supplements. The reason is that these treatments strengthen bones and reduce fracture rates. Ongoing research examines the use of growth hormones and genetic therapies for fragile bone disease.



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