Brittle bone disease or Osteogenesis Imperfecta (OI) is a rare bone disease. It is a genetic disorder which results in defects in the protein called collagen that is responsible for making stronger bones. Children suffering from the diseases have weaker bones that are susceptible to fractures. Collagen is the building brick of every tissue in the body, not just the bones. So in addition to fractures, there may be muscle weakness, joint laxity, spinal deformities, stunted growth, lung disease, teeth abnormalities, eye problems, deafness etc. It can severely affect the quality of life depending on its type and severity. Some children may have only a few fractures, while the more severe types can result in 100s of fractures. Read more about different types of fractures.
The exact prevalence of OI in Indian population is not known. However, in the west, the estimated range varies between 1 in 20000 and 1 in 50000. The prevalence is likely to be significant in India, but I suspect that it is being under diagnosed. Here’s information on another rare disease affecting children: bone cancers.
There are mainly eight types of the disease. Type I is the commonest type where the child may have only a few fractures during childhood and may have insignificant impact. Type II is a very severe form of OI where most children do not survive because of the inability to withstand trauma of delivery. These children have multiple intrauterine fractures and often do not survive. Type III is a severe form in which mobility is significantly impaired.
Osteogenesis Imperfecta (OI) is a genetic disorder which results due to defects in the protein called collagen that is responsible for making stronger bones. Because the body’s ability to make strong bones is affected, the person suffering from the diseases has weaker bones that are susceptible to fractures.
This disease is not always hereditary. Researchers have identified 8 different types of OI and the inheritance pattern is variable in different types. Some types of OI can be passed to the next generation, while others remain only as carriers without any clinical symptoms. In one type of OI, there is a 50% chance of the defective gene and disease being passed onto the next generation.
Diagnosis is complicated as there is no single diagnostic test to confirm the disease. The disease is suspected mostly with clinical symptoms and some radiological tests. In cases where OI is confirmed, molecular and genetic tests are done to verify whether the mutation is present in the gene coding for collagen. Ultrasound during pregnancy can help diagnose Type II disease.
The disease has no cure. Treatment options are twofold:
a) Medical: Bisphosphonates, a group of drugs that prevents bone loss, are generally given to the patient either intravenously or orally. Bisphosphonates have revolutionised the treatment of OI by decreasing the frequency and severity of fractures.
b) Surgical: A rodding surgery is often required to stabilise the weaker bones. The current mode of surgery involves the use of telescopic and non-telescopic rods. Telescopic rods are thinner and they allow the bones to grow and lengthen along with growing bones. Non-telescopic rods do not expand. They are used when there is no scope of bone growth.
After undergoing rodding surgery, Askar is now able to sit upright with the help of support. ‘We expect the child to come back for follow up and further reconstructive surgeries by the middle of the year. Askar might be able to stand on his feet,’ said Dr Padman.
Complications depend on the type of OI and the affected tissues. Collagen is the building brick of every tissue in the body, not just the bones. So in addition to fractures, children suffering from OI can have muscle weakness, joint laxity, spinal deformities, stunted growth, lung disease, teeth abnormalities, eye problems, deafness etc. Type II OI is a very severe form of OI where most children do not survive because of the inability to withstand trauma of delivery. These children have multiple intrauterine fractures and often do not survive.