The following information may help to address your question:
How is osteogenesis imperfecta inherited?
Osteogenesis imperfecta (OI) is most commonly inherited
in an autosomal dominant
manner. This means that having only one changed (mutated
) 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 (a de novo
mutation). 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 recessive
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.
Last updated: 10/9/2015
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 to also have OI.
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
. 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: 12/2/2015
Is genetic testing available for osteogenesis imperfecta?
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. 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
) 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.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?
Last updated: 7/15/2016
We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please
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