Osteogenesis Imperfecta

Understanding the condition

From: MedlinePlus, National Library of Medicine

Osteogenesis imperfecta (OI) is a genetic disorder in which bones fracture (break) easily. Sometimes the fractures happen for no known reason. OI can also cause weak muscles, brittle teeth, a curved spine, and hearing loss. OI is caused by one of several genes that aren't working properly. When these genes don't work, it affects how you make collagen, a protein that helps make bones strong.

OI can range from mild to severe, and symptoms vary from person to person. A person may have just a few or as many as several hundred fractures in a lifetime.

There is no specific test for OI. Your doctor uses your medical and family history, physical exam, and imaging and lab tests to diagnose it. Your doctor may also test your collagen (from skin) or genes (from blood). There is no cure, but you can manage symptoms. Treatments include exercise, pain medicine, physical therapy, wheelchairs, braces, and surgery.

Genetic causes described in the linked summary

From: MedlinePlus Genetics

Osteogenesis imperfecta can be caused by mutations in one of several genes. Mutations in the COL1A1 and COL1A2 genes cause approximately 90 percent of all cases. These genes provide instructions for making proteins that are used to assemble type I collagen. This type of collagen is the most abundant protein in bone, skin, and other connective tissues that provide structure and strength to the body.

Osteogenesis imperfecta type I is caused by mutations in the COL1A1 gene or, less commonly, the COL1A2 gene. These genetic changes reduce the amount of type I collagen produced in the body, though the molecules that are produced are normal. A reduction in type I collagen causes bones to be brittle and to fracture easily. The mutations that cause osteogenesis imperfecta types II, III, and IV occur in either the COL1A1 or COL1A2 gene. These mutations typically alter the structure of type I collagen molecules, resulting in abnormal type I collagen. A defect in the structure of type I collagen weakens connective tissues, particularly bone, resulting in the characteristic features of these more severe types of osteogenesis imperfecta.

Mutations in other genes cause rare forms of osteogenesis imperfecta. Many of these genes provide instructions for proteins that help process type I collagen into its mature form. Mutations in these genes disrupt different steps in the production of collagen molecules. These changes weaken connective tissues, leading to severe bone abnormalities and problems with growth. Other genes involved in osteogenesis imperfecta provide instructions for making proteins that control the development and function of bone-forming cells. Mutations in these genes impair normal bone development, causing the bones to be brittle and to fracture easily.

Inheritance described in the linked summary

From: MedlinePlus Genetics

When caused by mutations in the COL1A1 or COL1A2 gene, osteogenesis imperfecta has an autosomal dominant pattern of inheritance, which means one copy of the altered gene in each cell is sufficient to cause the condition. Many people with type I or type IV osteogenesis imperfecta inherit a mutation from a parent who has the disorder. Most infants with more severe forms of osteogenesis imperfecta (such as type II and type III) have no history of the condition in their family. In these infants, the condition is caused by new (sporadic) mutations in the COL1A1 or COL1A2 gene. Type V is also inherited in an autosomal dominant pattern.

Less commonly, osteogenesis imperfecta has an autosomal recessive pattern of inheritance. Autosomal recessive inheritance means two copies of the gene in each cell are altered. The parents of a child with an autosomal recessive disorder typically are not affected, but each carry one copy of the altered gene. Types VI through XVIII follow this pattern of inheritance.

Osteogenesis imperfecta type XIX is inherited in an X-linked recessive pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes in each cell. In males, who have only one X chromosome, a mutation in the only copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked recessive disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.

Which doctor should you see?

The suggested department for discussing Osteogenesis Imperfecta is Orthopaedics, with a orthopaedic specialist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• What explains the change in pain, movement or function?
• Which activities need adjustment while the diagnosis is being clarified?
• What are the roles of rehabilitation, observation and surgery in this situation?

Treatment discussions and follow-up

Where the source describes treatments, these are an overview of possible care, not a prescription for an individual. Ask which option applies to the confirmed diagnosis, what benefit is expected, what adverse effects to watch for and how progress will be assessed. Availability, approvals and local practice can differ from the country described in the source.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.