What Is Brittle Bone Disease?
Brittle bone disease is a disorder that results in fragile bones to break easily. It’s typically present at birth, but it only develops in children who have a family history of the disease. The disease is often referred to as osteogenesis imperfecta (OI), which means “imperfectly formed bone.”
Brittle bone disease can range from mild to severe. Most cases are mild, resulting in few bone fractures. However, the severe forms of this disease can cause:
Osteogenesis imperfecta (OI) is a group of genetic disorders that mainly affect the bones. People with this condition have bones that break easily, often from little or no trauma. Severity varies among affected people. Multiple fractures are common, and in severe cases, can even occur before birth. Milder cases may involve only a few fractures over a person’s lifetime.
There are various recognised forms of OI which are distinguished by their features and genetic causes. Depending on the genetic cause, OI may be inherited in (more commonly) or autosomal recessive manner. Treatment is supportive and aims to decrease the number of fractures and disabilities.
OI can sometimes be life-threatening if it occurs in babies either before or shortly after birth. Approximately one person in 20,000 will develop brittle bone disease. It occurs equally among males and females and among ethnic groups.
What Causes Brittle Bone Disease?
Brittle bone disease is caused by a defect, or flaw, in the gene that produces type 1 collagen, a protein used to create bone. The defective gene is usually inherited. In some cases, however, a genetic mutation, or change, can cause it.
What Are the Types of Brittle Bone Disease?
Four different genes are responsible for collagen production. Some or all of these genes can be affected in people with OI. Defective genes can produce eight types of brittle bone disease, labeled as type 1 OI through type 8 OI. The first four types are the most common. The last four are extremely rare, and most
The first four types are the most common. The last four are extremely rare, and most are subtypes of type 4 OI. Here are the four main types of OI:
Type 1 OI
Type 1 OI is the mildest and most common form of brittle bone disease. In this type of brittle bone disease, your body produces quality collagen but not enough of it. This results in mildly fragile bones. Children with type 1 OI typically have bone fractures due to mild traumas. Such bone fractures are much less common in adults. The teeth may also be affected, resulting in dental cracks and cavities.
Type 2 OI
Type 2 OI is the most severe form of brittle bone disease, and it can be life-threatening. In type 2 OI, your body either doesn’t produce enough collagen or produces collagen that’s poor quality. Type 2 OI can cause bone deformities. If your child is born with type 2 OI, they may have a narrowed chest, broken or misshapen ribs, or underdeveloped lungs. Babies with type 2 OI can die in the womb or shortly after birth.
Type 3 OI
Type 3 OI is also a severe form of brittle bone disease. It causes bones to break easily. In type 3 OI, your child’s body produces enough collagen but it’s poor quality. Your child’s bones can even begin to break before birth. Bone deformities are common and may get worse as your child gets older.
Type 4 OI
Type 4 OI is the most variable form of brittle bone disease because its symptoms range from mild to severe. As with type 3 OI, your body produces enough collagen but the quality is poor. Children with type 4 OI are typically born with bowed legs, although the bowing tends to lessen with age.
What Are the Symptoms of Brittle Bone Disease?
The symptoms of brittle bone disease differ according from one person to another pending on the type of the disease. Everyone with brittle bone disease does have fragile bones, but the severity varies from person to person. Brittle bone disease has one or more of the following symptoms:
How Is Brittle Bone Disease Diagnosed?
Your doctor can diagnose brittle bone disease by taking X-rays. X-rays allow your doctor to see current and past broken bones. They also make it easier to view defects in the bones. Lab tests may be used to analyse the structure of your child’s collagen. In some cases, your doctor may want to do a skin punch biopsy. During this biopsy, the doctor will use a sharp, hollow tube to remove a small sample of your tissue. Genetic testing can be done to trace the source of any defective genes.
How Is Brittle Bone Disease Treated?
There’s no cure for brittle bone disease. However, there are supportive therapies that help reduce your child’s risk of broken bones and increase their quality of life. Treatments for brittle bone disease include:
What Is the Long-Term Outlook for Someone with Brittle Bone Disease?
The long-term outlook varies depending on the type of brittle bone disease. Outlooks for the four main types of brittle bone disease are:
Type 1 OI
If your child has type 1 OI, they can live a normal life with relatively few problems.
Type 2 OI
Type 2 OI is often fatal. A child with type 2 OI may die in the womb or shortly after birth from respiratory problems.
Type 3 OI
If your child has type 3 OI, they may have severe bone deformities and often require a wheelchair to get around. They usually have shorter lifespans than people with type 1 or 4 OI.
They usually have shorter lifespans than people with type 1 or 4 OI.
Type 4 OI
If your child has type 4 OI, they may need crutches to walk. However, their life expectancy is normal or close to normal.
It is said there OI is now up to type 20. There can be a combination of symptoms of different type in one individual.
Frequently asked Questions
Q What is Osteogenesis Imperfecta (OI)?
A. Osteogenesis Imperfecta (OI) is a genetic condition characterised by bones that break easily, often from little or no apparent cause. The condition can vary quite drastically from person to person so a classification system has been identified to describe the different types of OI which is commonly used to help describe how severely a person with OI is affected. For example, a person may have just a few or as many as several hundred fractures in a lifetime.
Q What causes the condition?
A. OI is caused by a genetic mutation that affects the body’s production of collagen, which can be found throughout the body, especially in a person’s bones and other tissues
Q What are the symptoms?
A. As well as frequent fractured bones, people with OI often have muscle weakness, hearing loss, fatigue, joint laxity, curved bones, scoliosis, blue sclerae, dentinogenesis imperfecta (brittle teeth), and short stature amongst other medical problems.
Q Does OI only affect the bones?
A. Though fragile bones are the hallmark of OI, other medical problems, including loose joints, early hearing loss, brittle teeth, respiratory problems and easy bruising are also part of the condition
Q Does OI only affect Children?
A. OI is a genetic condition that is present throughout a person’s lifetime. The frequency of fractures may decrease after puberty, when growth stops. Later, it may increase again in women with the onset of menopause and in men due to age-related changes in their endocrine system
Q Is OI infections or contagious?
A. No, you cannot “catch” OI from a person who has the condition
Q How common is OI?
A. Few cases have been reported across the country. As proper statistics in the past have not been kept but it’s very common worldwide and well known in other African counties.
Q Is OI hereditary?
A. Yes, just sickle cell trait, genetic conditions such as OI are passed on from parents to children and this can occur in a number of ways, for instance, just one parent may pass on a defective copy of the gene or, in some cases, both parents. As we all have two copies of each gene with each parent passing one copy each to the new child there are instances where the condition is not passed on
Q Can people at risk of passing on the condition be tested?
A. Yes, people with OI or with known OI in their family can seek genetic counselling to discuss the chances of the condition being passed on to any children.
We would like to know if you have OI or if you know someone living in Nigeria with this illness. Contact us if you are a network centre, doctor, nurse as we would like to develop a Professional Network to provide support and information for people suffering with OI. Are you a professional or specialist working in the field of Osteogenesis Imperfecta and other rare bone diseases? Please get in touch!
Osteogenesis imperfecta (OI) is most commonly inherited. This means that having only one changed copy of the responsible gene in each cell is enough to cause features of OI. The mutated copy of the gene may be inherited from an affected parent, or it may occur for the first time in an affected person.
When a person with an autosomal dominant form of OI has children, each child has a 50% (1 in 2) chance of inheriting the mutated gene. If the child inherits the mutated gene, the child’s symptoms may be milder, or more severe, than those of the parent.
Less commonly, OI is inherited in an autosomal manner. This means that both copies of the responsible gene in each cell must have a mutation for a person to be affected. The parents of a person with an autosomal recessive condition typically are unaffected, but each carry one mutated copy of the gene. When two carriers of an autosomal recessive form of OI have children, each child has a 25% (1 in 4) chance to be affected, a 50% (1 in 2) chance to be a carrier like each parent, and a 25% chance to be unaffected and not be a carrier.
Organisations Supporting this Disease
Osteogenesis Imperfecta Foundation
804 West Diamond Avenue, Suite 210
Gaithersburg, MD 20878