What is osteogenesis imperfecta (OI)?

Updated: Feb 24, 2020
  • Author: Manoj Ramachandran, MBBS, MRCS, FRCS; Chief Editor: Harris Gellman, MD  more...
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Answer

Osteogenesis imperfecta (OI) is a disorder of bone fragility chiefly caused by mutations in the COL1A1 and COL1A2 genes that encode type I procollagen. Four types of osteogenesis imperfecta were originally described by Sillence in 1979 and are now used broadly as the Sillence criteria. [1]  The Nosology and Classification of Genetic Skeletal Disorders provided similar categorization in the 2010 revision. [2]  Precise typing is often difficult and depends in large degree on the experience of the clinician. Severity ranges from mild forms to lethal forms in the perinatal period.

Additional genes have been discovered in which mutations can also cause brittle bones. These are typically clinically indistinguishable and are considered by most to be subtypes of OI.

The earliest known case of OI is in a partially mummified infant’s skeleton from ancient Egypt now housed in the British Museum in London. In 1835, Lobstein coined the term osteogenesis imperfecta and was one of the first to correctly understand the etiology of the condition. Other names for OI are Lobstein disease, brittle-bone disease, blue-sclera syndrome, and fragile-bone disease.

OI is one of the most common skeletal dysplasias. It is a generalized disease of connective tissue that may manifest itself with one or more of the following findings:

  • Blue sclerae
  • Triangular facies
  • Macrocephaly
  • Hearing loss
  • Defective dentition
  • Barrel chest
  • Scoliosis
  • Limb deformities
  • Fractures
  • Joint laxity
  • Growth retardation

Additional features, such as constipation and sweating, may also occur.

Because OI is a genetic condition, it has no cure. A multidisciplinary approach is required to manage the disease. [3, 4, 5]  Medical treatments aimed at increasing bone mass and strength have gained popularity. [6, 7]  Orthotics play a limited role in management of OI and are used to stabilize lax joints and to prevent progressive deformities and fractures. It is more important to provide walking aids, specialized wheelchairs, and home adaptation devices to help improve the patient’s mobility and function. Surgery remains a pillar of treatment, [8] but it should be performed only if it is likely to improve function and only if the treatment goals are clear.


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