What is OI
Osteogenesis Imperfecta (OI) means “bones formed imperfectly”. It is a genetic condition that someone is born with and will always carry throughout their life. It primarily affects the bones, causing them to be fragile.
There are currently 5 ‘Types’ of OI (with many sub-types) that vary in the level of fragility and other accompanying properties. 17 genetic causes have been identified and research continues. It is estimated that roughly 7 people per 100 000 are born with OI. It is considered rare.
The mildest form of OI (Type I) is the most common and can often go undiagnosed until later in life. OI may also result in: short stature, blue tinted sclerae (the white of the eyes), hearing loss, brittle teeth, muscle weakness, hypermobility and restricted breathing.
Children born with more severe Types of OI can often sustain fractures in the womb or during childbirth. The most severe cases of OI can result in infant death, often due to respiratory failure during or shortly after birth. People with OI are all unique! No two people display exactly the same characteristics of OI, even within the established Types.
This video is about 10 common OI Myths and by Neel Desai, M.D., a father to a boy with Osteogenesis Imperfecta (OI). Share and subscribe to our Dr D Channel!
What Causes OI
Osteogenesis imperfecta (OI) is the result of a mutation in one of the two genes that carry instructions for making type 1 collagen (the major protein in bone and skin). 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 OI, a person has either less collagen than normal, or a poorer quality of collagen than normal, leading to weak bones that fracture easily.
OI is most often caused by a mutation (error) in one of two genes affecting the production of collagen. Collagen is the main structural protein in the human body – like the framework or scaffolding of a building. The body uses collagen in bones, muscles, tendons, skin and many other areas to provide structural support.
The two most common mutations cause either not enough collagen to be produced, or poor quality collagen – both resulting in structural weakness. A genetic mutation causing OI may have been inherited from one or both parents (who may or may not display OI themselves) or it can be the result of a new, random mutation.
Genetic testing can determine if a person has OI and which Type it is, though a preliminary diagnosis is often made on sight by a doctor who is very familiar with the condition.
OI is not something you can ‘catch’ or spread to others. It is not the result of poor nutrition or a lack of calcium (one of many old wives tales!).
OI occurs equally among the sexes and affects people on every continent across the globe.
How is OI diagnosed
OI is usually diagnosed as a result of family history and/or clinical observation. In most cases OI will be detected early on in a child’s life as a result of the child having a number of fractures. In addition to this some key clinical observations may be present such as:
Blue Sclerae (whites of the eyes) – this is a characteristic feature of OI Type 1 but is not present in all forms of OI.
Opalescent teeth – again this is not always present in all types of OI
Family history – understanding family history is a step in diagnosing OI, however in many cases there may be no family history of OI.
Blood tests – taken to measure the level of calcium, phosphorus and an enzyme called serum alkaline phosphate (SAP). It is also used to exclude other causes of osteoporosis.
Urine tests – these tests are undertaken to determine the level of bone breakdown and bone turnover.
X-rays – a skull x-ray may indicate the presence of Wormian bones, which are extra bones in the skull of many OI patients.
Bone density is also used to identify OI in patients. This is usually undertaken by a special x-ray machine called a DEXA scan.
Genetic testing – This can also be undertaken to anaylse the particular genes that cause OI however, in most cases this is not conducted due to both the expense and time consuming nature of doing these tests.
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