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Genetic and Rare Diseases Information Center (GARD)

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Osteogenesis imperfecta


Other Names for this Disease
  • Brittle bone disease
  • Fragilitas ossium
  • OI
  • Vrolik disease
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Your Question

I have a cousin with osteogenesis imperfecta. Neither of his parents has the dominant gene. Is there a genetic test that can be done to determine whether I am a carrier?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

How is osteogenesis imperfecta inherited?

Most types of osteogenesis imperfecta (OI) have an autosomal dominant pattern of inheritance, which means one copy of the altered gene in each cell is sufficient to cause the condition. The altered copy of the gene may be inherited from an affected parent, or it may occur for the first time in an affected individual. Each child of an individual with a dominantly inherited form of OI has a 50% (1 in 2) chance of inheriting the mutation.[1] The child would have the same OI-causing mutation as the parent, although the child’s symptoms may be milder or more severe than the parent’s symptoms.[2] Many people with type I or type IV OI inherit a mutation from a parent who has the disorder, while most infants with more severe forms (such as type II and type III) have no history of the condition in their family and have a new (sporadic) mutation that occurred for the first time in their cells.[3]

Less commonly, osteogenesis imperfecta has an autosomal recessive pattern of inheritance. Autosomal recessive inheritance means that 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 (they are referred to as carriers). When two carriers for an autosomal recessive condition have children, each child has a 25% (1 in 4) risk to have the condition, a 50% (1 in 2) risk to be a carrier, and a 25% chance to not have the condition and not be a carrier. The children of an individual with an autosomal recessive type of OI are always carriers for a disease-causing mutation.[1] Some cases of osteogenesis imperfecta type III are autosomal recessive, as well as some other types of OI that are caused by mutations in the CRTAP or LEPRE1 genes.[3]

It is recommended that couples at risk of having a child with OI seek genetic counseling before conception, or as early in the pregnancy as possible. A genetic counselor can provide information on OI genetics and prenatal diagnosis.[2] Instructions for locating a genetics professional are provided in the Services tab of the home page for this topic.

Last updated: 10/5/2011

What does it mean if an individual has osteogenesis imperfecta (OI) and neither of his/her parents has an OI mutation?

For autosomal dominant forms of osteogenesis imperfecta (OI), the condition may be inherited from an affected parent or the disease-causing mutation may occur for the first time in the affected individual. The number of cases that are caused by new mutations (called de novo mutations) varies by the severity of disease. Generally, the more severe the disease is, the more likely it is to be caused by a de novo mutation. Evaluation of parents of an affected individual with an apparent de novo mutation may include a clinical exam and genetic testing if the mutation in the affected individual has been identified. The risk to other family members depends on the genetic status of the affected individual's parents. If a parent is affected, his or her family members are at risk.[4]

When the parents of an affected individual do not have any signs or symptoms of OI, there is still a risk of about 5% for siblings of the affected individual to have OI. This is because it is possible (but uncommon) for one of the parents to have somatic and/or germline mosaicism.[4] Somatic cells are all of the cells of the body except the egg and sperm cells. Somatic mosaicism means that there are two or more genetic cell lines within the cells of the body (i.e. one cell line with the disease-causing mutation and one cell line without). Germline cells are the reproductive cells (egg and sperm cells). Germline mosaicism means that there are two or more genetic cell lines that are present only in the egg or sperm cells. A fact sheet with additional information about mosaicism is available on the Centre for Genetics Education's Web site and can be viewed by clicking here.

Last updated: 10/5/2011

Is genetic testing available for osteogenesis imperfecta?

Genetic testing is available for individuals with osteogenesis imperfecta. The rate for detecting mutations in the genes that are responsible for OI varies depending on the type.[4] Carrier testing may be available to relatives of affected individuals if the type of OI, disease-causing gene, and specific mutation in the affected individual are known.

Prenatal testing for at-risk pregnancies can be performed by analysis of collagen made by fetal cells obtained by chorionic villus sampling (CVS) at about ten to 12 weeks' gestation if an abnormality of collagen has been identified in cells from the affected individual. Analysis of collagen after an amniocentesis (usually performed at 15-20 weeks gestation) is not useful, because the cells obtained do not produce type I collagen. However, prenatal testing can be performed by analyzing the genes (molecular genetic testing) if the specific mutation has been identified in the affected relative.[4]

GeneTests lists the names of laboratories that are performing genetic testing for different types of osteogenesis imperfecta. To view the contact information for the clinical laboratories conducting testing, click here and click on "Testing" next to the type of OI in which you are interested. Please note that most of the laboratories listed through GeneTests do not accept direct contact from patients and their families; therefore, if you are interested in learning more, you will need to work with a health care provider or genetics professional. Genetics professionals, such as genetic counselors, can also explain the inheritance of OI in detail including information about genetic risks to specific family members.
Last updated: 4/5/2012

How can I find a genetics professional in my area?

Genetics clinics are a source of information for individuals and families regarding genetic conditions, treatment, inheritance, and genetic risks to other family members. More information about genetic consultations is available from Genetics Home Reference. To find a genetics clinic, we recommend that you contact your primary healthcare provider for a referral.

The following online resources can help you find a genetics professional in your community:
Last updated: 10/18/2013

References