Osteogenesis Imperfecta (OI)

Osteogenesis imperfecta, usually shortened to OI and often called brittle bone disease, is a genetic condition in which bones break more easily than they should.

At its root, OI is about collagen, the protein that gives bone its strength and flexibility.

Understanding the genetics behind OI helps you and your family make sense of a diagnosis, plan ahead, and know what to watch for over a lifetime.

Our clinic in Tulsa, OK is the only Oklahoma practice listed in the Osteogenesis Imperfecta Foundation’s clinic directory for adults living with OI.

On this page

• What is osteogenesis imperfecta?
• Is osteogenesis imperfecta genetic or inherited?
• Why genetic testing matters, and which test to use
• How to read OI genetic test results
• Diagnosis when genes do not tell the whole story
• Osteogenesis imperfecta vs. osteoporosis
• Adult OI care in Tulsa, Oklahoma

What is osteogenesis imperfecta?

Osteogenesis imperfecta is an inherited disorder of bone that leaves the skeleton fragile from birth.

Most bone is built on a framework of type 1 collagen. Think of collagen as the steel rebar inside concrete: it lets bone bend a little under stress instead of snapping.

In OI, a change in the genes that carry the recipe for collagen means the body either makes too little collagen, or makes collagen that is the wrong shape.

Either way, the result is bone that is more fragile than normal.

What causes osteogenesis imperfecta?

Genes are the instructions our cells use to build the body, and we each carry two copies of most genes, one from each parent.

Usually those instructions work exactly as intended. Occasionally a gene carries a change, sometimes called a mutation or a variant, that alters the instructions.

When the affected gene is one that helps build collagen, OI can be the result.

Most cases trace back to the two genes that carry the instructions for type 1 collagen, COL1A1 and COL1A2, though changes in a number of other genes can cause OI as well.

Is osteogenesis imperfecta genetic or inherited?

OI is always genetic, but it is not always inherited from a parent.

That distinction is the point families most often get wrong, and it matters.

A gene change causes the condition in every case. In some families that change is passed down. In others it appears for the first time in the child.

Knowing which pattern applies to your family matters for understanding the chance of passing OI on, and for making informed decisions about family planning.

Dominant inheritance, the most common pattern

In about 90 percent of people with OI, only one of the two gene copies carries the change, and that single copy is enough to cause the condition.

This dominant form is usually tied to the collagen genes.

A person with dominant OI has about a 50/50 chance of passing it to each child, whether or not they inherited it themselves.

Recessive inheritance, less common

In about 5 to 10 percent of cases, OI only appears when a child inherits a changed copy of the same gene from both parents.

The parents usually have no symptoms themselves, because their one working copy is enough to keep their own bones healthy. They are carriers.

When both parents are carriers, there is about a 25 percent chance in each pregnancy of having a child with this form of OI.

X-linked inheritance, rare

Fewer than 5 percent of OI cases are tied to a gene on the X chromosome.

Because of how the X chromosome is inherited, this pattern typically affects sons, who inherit the change from a mother who usually has no symptoms.

This is the least common of the three patterns.

Why does genetic testing matter for OI?

OI can often be recognized from physical signs and family history alone, so why test the genes?

Because a clear genetic answer can do four things.

• Confirm the diagnosis when the picture is uncertain or overlaps with other bone conditions.
• Identify which type of OI is present, which helps guide monitoring and treatment.
• Clarify how OI is being inherited in your family, which is useful information for family planning.
• Open the door to research studies and, in some cases, newer treatment options.

What types of genetic testing are used for OI?

Testing is usually done from a simple blood or saliva sample, and which test makes sense depends on your situation.

• Bone fragility (OI) gene panel. Checks many genes known to cause OI at once. This is often the best first step when no gene change has been identified in the family yet.
• Whole exome or genome sequencing. A broader look, used when a panel does not provide an answer.
• Single gene testing. When a specific gene change is already known in the family, testing can target just that change.

How do you read OI genetic test results?

Genetic labs sort each finding into categories that describe how confident they are that a change actually causes disease.

In plain terms, here is what each category means.

A negative test does not always rule OI out. It may simply mean the test that was run did not cover the right gene.

If a limited test comes back negative but the clinical picture still fits OI, broader testing, or a look at conditions that resemble OI, may be the next step.

How is OI diagnosed when genes do not tell the whole story?

Genetic testing is a powerful tool, but it is not the only one.

OI is frequently recognized from a combination of clinical signs and family history.

Those signs include frequent fractures from little or no injury, bone deformities, a bluish tint to the whites of the eyes, hearing changes, short stature, and loose joints.

In many families the diagnosis is made on this clinical picture, with testing used to confirm it, pin down the type, or guide planning.

A careful history and a hands-on physical examination stay central to bone care here, the same way they do when we evaluate a suspected vertebral compression fracture.

Osteogenesis imperfecta vs. osteoporosis: what is the difference?

OI and osteoporosis both lead to fragile bones, but they are not the same thing.

OI is about how bone is built. Osteoporosis is about how much bone is lost over time.

Here is the part that matters most for anyone living with OI: you can have both.

Because OI already leaves bone more fragile, many adults with OI are at higher risk of developing osteoporosis, and often earlier in life than the general population.

That makes ongoing bone health monitoring especially valuable.

Watching bone density over time means thinning bone can be caught and treated before it leads to a fracture, rather than after.

Adult OI care in Tulsa, Oklahoma

Managing OI works best as a team effort.

A genetic counselor helps you understand your test results, sort out inheritance patterns, and think through family planning.

A medical geneticist, or a bone health specialist, helps monitor bone density and decide whether treatments to strengthen bone are appropriate.

Our focus at Dr. James Webb & Associates is on protecting and strengthening bone: thorough evaluation, advanced bone quality testing, and a plan built around you.

That includes watching for the earlier onset osteoporosis that adults with OI are more prone to, and treating spinal fractures if they occur.

Whether you are working through a new OI diagnosis or you simply want a clear picture of your bone health, our Tulsa team is here to help, with a focus on treating pain and protecting bone without unnecessary surgery.