Osteogenesis Imperfecta.
Last updated Thursday, December 23, 2004
SymptomsWhat are symptoms of osteogenesis imperfecta? There are four distinct types of OI: types I, II, III, and IV.
The type of OI is consistent, or "runs true," in a family. For
example, a parent with OI type IV will not have a child with OI type
III. The diagnosis of the type of OI is made based upon information
obtained from the person's physical examination, family history, and
X-ray studies. A skin biopsy often is done. This involves removing a
tiny piece of skin, usually from the back of the arm. The skin cells
are grown in culture and the collagen is studied.
OI Type I
OI type I is the most common type of OI. It is inherited in an
autosomal dominant pattern but may occur as a result of a spontaneous
mutation. People with OI type I have an average of 20 to 40 fractures
before puberty. Fewer fractures occur after puberty. Prenatal diagnosis
often is possible. People with OI type I have one or more of the
following features:
- fragile bones
- triangular-shaped face
- blue sclerae (the white part of the eye)
- hearing loss beginning in the teens, twenties, or thirties
- curvature of the spine (scoliosis)
- thin, smooth skin
OI Type II
About 10 percent of people with OI have OI type II. OI type II
results from a new mutation. OI type II is a very severe form of OI.
Infants with this form of OI have fractures before birth, have
extremely fragile bones, and usually die shortly after birth. Prenatal
diagnosis is possible.
OI Type III
Approximately 20 percent of people with OI have OI type III. It
usually results from a new dominant mutation. These people often have
many spontaneous fractures. It is not unusual for a person to have 20
or more fractures occurring during the first three years of life and
more than 100 fractures by puberty. Loose joints and poor muscle
development are common. Prenatal diagnosis often is possible.
Characteristic features include:
- soft bones that not only break but also bend easily
- misshapen arms and legs
- compressed vertebrae and severe curvature of the spine (scoliosis)
- severely misshapen chest that may cause problems with breathing
- poor development of the teeth (dentinogenesis imperfecta), causing teeth to be discolored and to break easily
- mild to severe hearing loss in adult life
- short stature (some people may only grow to be three feet tall)
OI Type IV
OI type IV is inherited in an autosomal dominant pattern, although
some people have the disorder as a result of a new dominant mutation.
In OI type IV, most fractures occur during childhood, but women often
have a recurrence of fractures after menopause. Typical features
include:
- pale blue sclerae at birth that become white by adulthood
- curvature of the spine
- loose, easily overstretched joints
- dentinogenesis imperfecta
- mild short stature
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