From the Guidelines
Osteogenesis Imperfecta (OI) is a collagen type I disorder, where mutations in the genes involved in the biosynthesis of collagen type I result in fragile bones. This genetic disorder results from mutations in the genes that encode the alpha chains of type I collagen, leading to either reduced production of normal collagen or the formation of structurally abnormal collagen molecules 1. The severity of the condition varies widely depending on the specific genetic mutation and how it affects collagen synthesis or structure. Key characteristics of OI include:
- Fragile bones that break easily
- Variable severity of manifestations
- Involvement of other organ systems, including the lungs
- Need for a standard set of outcomes and measuring instruments for care Some important aspects of OI include:
- Type I collagen is essential for providing strength and structure to bones, skin, tendons, and other connective tissues
- Mutations in the COL1A1 and COL1A2 genes encode the alpha chains of type I collagen
- Treatment typically focuses on managing symptoms through physical therapy, surgical interventions, and sometimes medications like bisphosphonates to increase bone density, though these approaches don't correct the underlying collagen defect 1.
From the Research
Type of Collagen Affected in Osteogenesis Imperfecta (OI)
Causes of OI
- OI is caused by dominant autosomal mutations in the type I collagen coding genes (COL1A1 and COL1A2) in about 85% of individuals, affecting collagen quantity or structure 2.
- Mutations in the type I collagen genes can lead to quantitative or qualitative defects in type I collagen 4.
- Defects in other proteins involved in type I collagen synthesis, processing, secretion, and post-translational modification can also cause OI 2, 3, 5.
Forms of OI
- The most common form of OI is caused by mutations in the two collagen type I genes, with stop mutations leading to reduced collagen amount and missense mutations provoking structural alterations in the collagen protein 3.
- Autosomal recessive forms of OI are caused by deficiency of proteins that interact with type I procollagen for post-translational modification and/or folding 5.