General Information / OI Types

What is Osteogenesis Imperfecta (OI)?

Osteogenesis Imperfecta (OI) is a broad group of genetic mutations that cause a defect in the way the body manufactures collagen.  The general defects are the insufficient production of normal collagen and/or the production of abnormal collagen.

The most common and obvious effect is brittle bones.  There are currently 4 classifications or types, with each type having a range in severity.  Because most cases of OI are new genetic mutations, each person's genetic defect is slightly different.  This means that each person with OI is different from each other person in regards to the specific effect this has on thier body.  Some people tend to break only certain bones, while others seem to (and sometimes do) break just about everything.  The severity of OI is extremely broad.  The most mildly affected people may not ever break a bone or may break only a couple times in their life, while the most severely affected break hundreds of times and may die prematurely from fractures, skeletal deformities, respiratory or other complications.

Types (classifications) of OI.

This list of OI type classifications IS out of date. Several additional types have been described in the last few years.


This is generally the mildest form of OI.  People with this type may not fracture at all or may have up to a dozen or more fractures in their lifetime.  Usually fractures will be easily explainable as being caused by sports injuries, accidents or hard falls.  More severely affected individuals with this type may fracture easily from light trauma such as a bump, light fall or twisting/pulling motions.  Often, children with this type of OI sustain fractures that are not easily explained or not caused by obvious trauma and the parents may sometimes be accused of child abuse.  One of the distinguishing features of people with this type of OI is that they have blue (ranging from light grey-blue to intense blue) sclera (whites of the eyes).  Most are of average or nearly average height.  Some people may have a moderate to severe hearing loss begining in thier teens-twenties, barrel chest, scoliosis, underbite and bruise easily.

Type II

This is the severest form of OI and is sometimes called the perinatal lethal type.  Many children with this type die during or shortly after birth.  Most have many fractures at birth, deformed or bowed limbs and hydrocephalus with evidence of healed/healing fratures before birth (seen on sonograms and x-rays).  Most will have dozens of fratures per year, with many being spontaneous/stress fractures or from very light trauma such as from rolling over, being picked up or sitting.  Few people with this type will achieve much independance due to the constant numerous fractures and other complications.

Type III

This type is usually fairly severe.  People with this type are generally moderately to extremely short statured, most will not be able to walk without some type of aid and many will never be able to walk.  Most have from a few to dozens of fractures yearly which may be caused by light trauma (bumps, twisting, falls, lifting), walking (or trying to) or may be spontaneous.  Many children will have fractures at birth and show evidence of fractures in utero.  Most will have bowed or shortened limbs and a triangular shaped head.  Some people may have blue sclera, underbite, scoliosis, large protruding (buggy) eyes, high pitched voice, barrel chest.  For many people, fractures rates drop after puberty and many people with this type are able to become fairly independent by their teen or early adult years.

Type IV

Type IV is generally moderate to severe.  Many people will be able to walk un-aided while others will need crutches or braces to walk and some may not walk.  Children may have fractures at birth and some show signs of fractures in utero.  Many will have up to a few fratures yearly, but some people may go several months or even years between fratures, especially after puberty.  The majority of fractures are caused by mild to moderate trauma, but there may be some spontaneous fractures.  Many children have fractures of a type that is common with child abuse (spiral fracture) leading parents to become suspected of child abuse in some cases.  Many people will be slightly to moderately short statured and may have short or bowed limbs, barrel chest, scoliosis, large eyes, underbite, triangular shaped head or face and some may have blue sclera.  Many are able to participate in non-contact sports such as golf or swimming and most people are able to become independent.

Go to the Osteogenesis Imperfecta Foundation, Inc. web page

 page last updated 3/24/98

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