What is osteogenesis imperfecta?
Osteogenesis imperfecta (OI) is a group of rare genetic disorders. People with OI have bones that may break or fracture easily. Breaking or fracturing of the bones occurs because of very mild trauma (that would not break bones in a person without OI), or with no trauma or cause. OI is also called 'brittle bone disease.' There are several forms and the symptoms and severity can be very different among people with this disorder. Some people will only be mildly affected and have a slightly increased risk of breaking bones. They may only have premature osteoporosis, a condition where bone mass is reduced making people more likely to have a bone fracture. Osteoporosis commonly affects people, even those without OI, as they grow older. Other people with OI may frequently break or fracture bones. The most severe form can cause death just before or just after birth (OI type II). This is known as the perinatal period. Other symptoms include problems affecting the teeth, loose skin or ligaments, or abnormal curving of the spine. Some people may be very short when they stop growing, a condition called short stature. Certain forms may cause hearing loss in later childhood or as an adult.
OI is a genetic disorder. This means that people have a problem in a specific gene. People have about 20,000-25,000 genes in their bodies. Genes are like our body's instruction manual - they control the growth, development and normal function of the body. Because of a change in one of at least several different genes, people with OI lack a protein, have an abnormal protein or have low levels of an abnormal protein. Most of these proteins are involved in the creation, health and proper function of collagen. Collagen is the major structural protein in the body. Problems in collagen production weaken connective tissue, which in turn makes bones weaker and prone to fracturing or breaking. More than 90% of people with OI have changes (mutations) in two genes, the COL1A1 and the COL1A2 genes.
Osteogenesis Imperfecta. The Genetics Home Reference website. Accessed April 6, 2017. https://ghr.nlm.nih.gov/condition/osteogenesis-imperfecta
Steiner RD, Adsit J, Basel D. COL1A1/2-Related Osteogenesis Imperfecta. GeneReviews website. Accessed April 6, 2017. https://www.ncbi.nlm.nih.gov/books/NBK1295/
Osteogenesis Imperfecta. The National Organization for Rare Disorders website. Accessed April 6, 2017. https://rarediseases.org/rare-diseases/osteogenesis-imperfecta/