Osteogenesis imperfecta is a condition causing extremely fragile
bones.
Osteogenesis
imperfecta (OI) is a congenital disease, meaning it is present at birth. It is
frequently caused by defect in the gene that produces type 1 collagen, an
important building block of bone. There are many different defects that can
affect this gene. The severity of OI depends on the specific gene defect. OI is
an autosomal dominant disease. That means if patient has one copy of the gene,
he/she will have the disease. Most cases of OI are inherited from a parent,
although some cases are the result of new genetic mutations.
A patient with OI has a 50% chance of passing
on the gene and the disease to their children.
Symptoms:
All patients
with OI have weak bones, which makes them susceptible to fractures. Persons
with OI are usually below average height (short stature). However, the severity
of the disease varies greatly.
1.
Blue tint to
the whites of their eyes (blue sclera)
2.
Multiple
bone fractures
3.
Early hearing
loss
4.
Because type
I collagen is also found in ligaments, patients with OI often have loose joints
(hypermobility) and flat feet. Some types of OI also lead to the development of
poor teeth.
5.
Bowed legs
and arms
6.
Kyphosis
7.
Scoliosis
(S-curve spine)
Signs:
OI is
usually suspected in children whose bones break with very little force. A
physical examination may show that the whites of their eyes have a blue tint.
A definitive diagnosis may be made using a
skin punch biopsy. Family members may be given a DNA blood test.
If there is
a family history of OI, chorionic villus sampling may be done during pregnancy
to determine if the baby has the condition.
The severe form of type II osteogenesis
imperfecta can be seen on ultrasound when the fetus is as young as 16 weeks.
Treatment:
There is not
yet a cure for this disease. However, specific therapies can reduce the pain
and complications associated with OI.
1.
Bisphosphonates are drugs that have been used to treat
osteoporosis. They have proven to be very valuable in the treatment of OI
symptoms, particularly in children. These drugs can increase the strength and
density of bone in persons with OI.
2.
Low impact exercises such as swimming keep muscles strong and
help maintain strong bones.
3.
In more
severe cases, surgery to place metal
rods into the long bones of the legs may be considered to strength the bone
and reduce the risk of fracture. Bracing can also be helpful for some people.
4.
Reconstructive surgery may be needed to correct any deformities.
Such treatment is important because deformities (such as bowed legs or a spinal
problem) can significantly affect a person's ability to move or walk.
Regardless of treatment, fractures will
occur. Most fractures heal quickly. Time in a cast should be limited since bone
loss (disuse osteoporosis) may occur when you do not use a part of your body
for a period of time.
Many children with OI develop body image
problems as they enter their teenage years. A social worker or psychologist can
help them adapt to life with OI.
Prognosis:
How well a
patient does depends on the type of OI he/ she has.
1.
Type I, is
the most common form. Persons with this type can live a normal lifespan.
2.
Type II is a
severe form that is usually leads to death in the first year of life.
3.
Type III is
also called severe OI. Patient with this type have many fractures starting very
early in life and can have severe bone deformities. Many become wheelchair
bound and usually have a somewhat shortened life expectancy.
4.
Type IV or
moderately severe OI, is similar to type I, although persons with type IV often
need braces or crutches to walk. Life expectancy is normal or near normal.
There are
other types of OI, but they occur very infrequently and most are considered
subtypes of the moderately severe form (type IV).
Complications:
Complications
are largely based on the type of OI present. They are often directly related to
the problems with weak bones and multiple fractures.
Complications
may include:
1.
Hearing loss
(common in type I and type III)
1.
Heart
failure (type II)
2.
Respiratory
problems and pneumonias due to chest wall deformities
3.
Spinal cord
or brain stem problems
4.
Permanent
deformity
Severe forms are usually diagnosed early in
life, but mild cases may not be noted until later in life. Make an appointment
with your health care provider if you or your child has symptoms of this
condition.
Prevention:
Genetic counselling
is recommended for couples considering pregnancy if there is a personal or
family history of this condition.
References:
Marini JC.
Osteogenesis imperfecta. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF,
eds. Nelson Textbook of Paediatrics. 19th ed. Philadelphia, Pa: Saunders
Elsevier; 2011: chap 692.
Dr. Imtiaz
Syed
M.B, B.S,
MBA, CRA, PCQI, CPC
LinkedIn: http://uk.linkedin.com/pub/imtiaz-syed/13/89/841
OpenDoor
Team member. www. OpenDoor.cc
Redditch,
Gloucestershire. UK.
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