- Brittle bone disease
- Fragilitas ossium
- Vrolik disease
Your QuestionWhat are the chances of passing osteogenesis imperfecta on to a child while pregnant? Can a vaginal delivery be perfomed or will a C-section be necessary?
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Mutations in the COL1A1, COL1A2, CRTAP, and LEPRE1 genes cause osteogenesis imperfecta (OI). Each of the genes that cause OI plays a role in how the body makes collagen. Collagen is a material in bones that helps make them strong. When these genes aren't working properly, there isn't enough collagen, or the collagen doesn't work properly. This leads to weak bones that break easily.
Most children inherit the gene that doesn't work properly from one parent. Some inherit it from both parents. In some cases, neither parent passes on this gene. Instead, the gene stops working properly soon after the child is conceived.
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 . 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. 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.
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 . 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.
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. Instructions for locating a genetics professional are provided in the Services tab of the home page for this topic.
Additional information regarding OI and pregnancy can be found through the Osteogenesis Imperfecta Foundation by clicking here.
- Osteogenesis imperfecta. Genetics Home Reference (GHR). 2007; http://ghr.nlm.nih.gov/condition=osteogenesisimperfecta. Accessed 11/11/2011.
- Osteogenesis Imperfecta. National Institute of Arthritis and Skeletal and Skin Diseases (NIAMS). 2007; http://www.niams.nih.gov/Health_Info/bone/Osteogenesis_Imperfecta/osteogenesis_imperfecta_ff.asp. Accessed 4/29/2009.
- Steiner RD, Pepin MG, Byers PH. Osteogenesis Imperfecta. GeneReviews. 2005; http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=gene&part=oi. Accessed 4/29/2009.
- Krakow D. OI Issues: Pregnancy Considerations for women with OI. Osteogenesis Imperfecta Foundation. 2007; http://www.oif.org/site/PageServer?pagename=PregOI. Accessed 4/29/2009.