An inborn disorder of bone formation, in which the bones are imperfectly formed and much more fragile than usual.
Fragile bone disease, glass-bone disease ; brittle bone disease ; OI.
What is this?
A congenital genetic error in the structure of bone and connective tissue, of different forms and variable severity, from lethal to mild. It occurs worldwide, though it is especially common in the Shona and Ndebele tribes in Zimbabwe.
What causes this?
There is an inborn abnormality in the formation of a particular type of collagen protein, a component in the makeup of bone and other tissues, including tendons and skin. There can be a family history, but many cases arise from new genetic mutations. If you have OI, there’s a 50 % chance of passing on the disorder to each child.
What are its symptoms?
The essential symptom is the occurrence of fractures after a very minor injury or stress, which may heal easily. Depending on the severity of the disorder, unexpected fractures occur in adults (in the mild form ), or in childhood ; in very severe forms, fractures can occur within the uterus and before birth. They may bruise easily, and may develop early deafness. They may have a high pain tolerance, so much so that the existence of some old and healed fractures may only be identified by x-ray.
How is it diagnosed?
A history of broken bones from mild trauma is typical. In some forms, the whites of the eyes are blue-gray. In more severe forms, distorted and misshapen bones may be recognised. The results of usual blood tests which would identify other forms of bone disease are usually normal. X-rays and skin or bone biopsies may show typical features. Mild forms may be mistaken for child abuse, and distinguishing between these conditions needs skilful assessment.
How is it treated?
There is no cure. Some centres use courses of intravenous Pamidronate to increase the mineral density and strength of the bone, and reduce the incidence of fractures. A diet, including enough calcium, phosphorus, and vitamin D, is helpful. Orthopaedic surgery may be needed to correct fractures and strengthen bones. Expert physiotherapy is important.
What is the prognosis?
Infants with the most severe forms usually die early in life, though some reach adulthood. With milder forms, the lifespan may be relatively normal.
When to call your doctor
This condition should be considered when a child fractures bones uncommonly easily; and it needs to be considered a possibility when child abuse is suspected on the basis of multiple or frequent fractures.
How can it be prevented?
There is no way to prevent the disorder, though genetic counselling once a case has been identified may limit the risk of the parents having more afflicted children. Extreme caution to avoid minor trauma may limit the number and extent of fractures. The condition has been identified in an Egyptian mummy from 1000 BC, and may have been the affliction from which the early Norse Viking King Ivar the Boneless, suffered. A number of celebrities have the condition, including actors and actresses, and American Olympic coxswain, and the brilliant jazz pianist Michel Petrucciani. It has been featured in a number of movies, including Unbreakable (2000) where Mr Glass is played by Samuel L. Jackson, Fragile (2005), and the character The Glass Man in Amelie (2001).
Copyright MA Simpson
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