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Osteogenesis imperfecta
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Osteogenesis imperfecta is a genetic disorder of connective tissue, the material that gives the body its support. What goes wrong is type I collagen: either it is not made properly or it is not processed properly.
Its shape comes with a surprising requirement. Three chains coil into a rigid triple helix, and for that helix to close, every third amino acid has to be glycine, the smallest residue that fits there. A triple helix only closes if every third link is the smallest one in the row.
In at least 90% of cases there is a defect in the amount of type I collagen, in its quality, or in both. And the disease is marked by bones that fracture easily and low bone density. That is why it is also called brittle bone disease.
In brief
Osteogenesis imperfecta is a genetic connective tissue disorder caused by an abnormality in the synthesis or processing of type I collagen.
That collagen forms a rigid triple helix, which is possible because glycine sits at every third position, the smallest residue that fits there.
A triple helix only closes if every third link is the smallest one in the row.
At least 90% of cases have a defect in the amount or the quality of that collagen. It is marked by easy fractures and low bone density.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingOsteogenesis Imperfecta, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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