CD-ROM Today (UK) (Spanish) 15/CDRT.iso/dp/0407/04073.txt

Text File | 1994-01-17 | 10KB | 230 lines

$Unique_ID{BRK04073}
$Pretitle{}
$Title{Osteopetrosis}
$Subject{Osteopetrosis Albers-Schonberg Disease Melorheistosis Osteopoikilosis
Osteogenesis Imperfecta}
$Volume{}
$Log{}

Copyright (C) 1987, 1990 National Organization for Rare Disorders, Inc.

354:
Osteopetrosis

** IMPORTANT **
It is possible the main title of the article (Osteopetrosis) is not the
name you expected.  Please check the SYNONYMS listing to find the alternate
names, disorder subdivisions, and related disorders covered by this article.

Synonyms

     Albers-Schonberg Disease
     Osteosclerosis Fragilis Generalisata
     Generalized Congenital Osteosclerosis
     Ivory Bones
     Marble Bones

Information on the following diseases can be found in the Related
Disorders section of this report:

     Melorheistosis
     Osteopoikilosis
     Osteogenesis Imperfecta

General Discussion

** REMINDER **
The information contained in the Rare Disease Database is provided for
educational purposes only.  It should not be used for diagnostic or treatment
purposes.  If you wish to obtain more information about this disorder, please
contact your personal physician and/or the agencies listed in the "Resources"
section of this report.


Osteopetrosis is a combination of several rare genetically caused
symptoms grouped together as one disorder.  It can be inherited as either a
dominant or recessive trait and is marked by increased bone density, brittle
bones, and in some cases, skeletal abnormalities.  Although symptoms may not
initially be apparent in people with mild forms of this disorder, trivial
injuries may cause bone fractures due to abnormalities of the bone.  The
dominantly transmitted form is milder than the recessive form of
Osteopetrosis, and may not be diagnosed until adolescence or adulthood when
symptoms first appear.  More serious complications occur in the recessive
form which may be diagnosed from examination of skeletal x-rays during
infancy or childhood.

Symptoms

Initial symptoms of the dominant form of Osteopetrosis may include bone
fractures caused by trivial injuries, and unusual dental problems.  Bone pain
may occur in the spine, and cranial nerves may be affected.  Some vision
defects or facial palsy may also be symptomatic of the dominant form of
Osteopetrosis.  Severe anemia may occur due to obliteration of the bone
marrow.

A more serious recessive form of Osteopetrosis is present at birth and
can be diagnosed by skeletal x-rays.  Symptoms may include retardation of
growth, enlargement of the head, a deformity of the base of the skull and
delayed closure of the soft spot on the skull of infants with this disorder.
Vision failure or cataracts, deafness, dental decay, chest deformity and
brain damage are also symptomatic of the more severe form of Osteopetrosis.

Bone defects may involve increased density of many bones including
vertebrae, ribs, long bones, the pelvis and the skull.  Concurrently there is
a decrease in density of the bone marrow in people affected by this disorder.

Causes

Osteopetrosis can be inherited as either a dominant or recessive trait.  The
basic defect in bone growth involves an insufficient production of
intercellular bone tissue by cells called osteoblasts.  These osteoblasts aid
in the production of bone by maintaining a balance between formation and loss
of calcium (resorption) in the bone.

Human traits including the classic genetic diseases, are the product of
the interaction of two genes for that condition, one received from the father
and one from the mother.

In dominant disorders, a single copy of the disease gene (received from
either the mother or father) will be expressed "dominating" the normal gene
and resulting in appearance of the disease.  The risk of transmitting the
disorder from affected parent to offspring is 50% for each pregnancy
regardless of the sex of the resulting child.

In recessive disorders, the condition does not appear unless a person
inherits the same defective gene from each parent.  If one receives one
normal gene and one gene for the disease, the person will be a carrier for
the disease, but usually will show no symptoms.  The risk of transmitting the
disease to the children of a couple, both of whom are carriers for a
recessive disorder, is twenty-five percent.  Fifty percent of their children
will be carriers, but healthy as described above.  Twenty-five percent of
their children will receive both normal genes, one from each parent and will
be genetically normal.

Affected Population

Osteopetrosis occurs in children and lasts throughout life.  The dominant
form (which is milder than the recessive form) may be present in childhood,
but not diagnosed until adolescence or adulthood.  Both forms of this
disorder affect males and females in equal numbers.  Osteopetrosis is very
rare.

Related Disorders

Melorheistosis is a rare disorder characterized by shortening or deformity of
one or more limbs due to a problem with calcium density in bones.  It is
inherited as a dominant trait.  Pain and limitation of movement of the
affected arm(s) or leg(s) is usually present.  The prognosis for this
disorder is guardedly favorable.

Osteopoikilosis, also known as "spotted bones", is a rare disorder which
may occur in conjunction with melorheostosis.  Usually without apparent
symptoms, Osteopoikilosis may be discovered during X-ray examination for
other bone growth disorders.  Symptoms usually occur most often between the
ages of fifteen and sixty.  Spotty shadows appear on x-rays of wrist and
ankle bones, finger or toe bones, long bones, pelvis, skull, and/or ribs
(spinal bones exempted).  These spots are less than one centimeter in
diameter and usually of uniform density.  Bone growth nodules can grow larger
or diminish and disappear.

Osteogenesis Imperfecta, or "brittle bone disease", is a group of
hereditary connective tissue disorders characterized by unusual bone
fragility and tendency to fracture.  Traditionally the disease has been
recognized in two forms.  Osteogenesis Imperfecta Congenita is apparent at
birth, while Osteogenesis Imperfecta Tarda manifests itself only later,
usually at three or four years of age.  OI Tarda tends to be a milder form of
the disease.  Both forms of Osteogenesis Imperfecta affect 1 in 20,000 to
50,000 births in the United States.  (For more information on this disorder,
choose "osteogenesis imperfecta" as your search term in the Rare Disease
Database.)

Therapies:  Standard

Treatment of Osteopetrosis is symptomatic and supportive.  Physical therapy
may be of benefit in some cases.  Genetic counseling can be of assistance for
families in which this disorder occurs.

Therapies:  Investigational

Experimental treatment of Osteopetrosis includes bone marrow transplantation.
Bone marrow is found inside the bone and produces white blood cells, red
blood cells, or clotting cells (platelets).  The transplant procedure
involves extracting cross-matched bone marrow from a healthy donor and
injecting it intravenously into a patient.  The healthy marrow cells enter
the general circulation and migrate through the blood to marrow cavities in
the patient's bones.  The new marrow cells begin to grow and produce new
white blood cells, red blood cells, and platelets.  The procedure involves
risks which must be balanced against possible benefits, and is used
experimentally in the most severe cases of Osteopetrosis.

The most serious cases of Osteopetrosis are also being treated
experimentally with a combination of steroids (prednisone) and a low calcium,
high phosphate diet.

Another alternative treatment is the administration of calcitriol, the
biologically active form of vitamin D.  High doses of this drug, which
stimulates bone-resorbing cells called osteoclasts, improved bone turnover in
patients on whom it was studied, and it increased formation of blood cells.
In one patient disease symptoms were reversed almost completely, but more
research is needed to determine long-term safety and effectiveness of the
experimental therapies.

This disease entry is based upon medical information available through
January 1990.  Since NORD's resources are limited, it is not possible to keep
every entry in the Rare Disease Database completely current and accurate.
Please check with the agencies listed in the Resources section for the most
current information about this disorder.

Resources

For more information on Osteopetrosis, please contact:

     National Organization for Rare Disorders (NORD)
     P.O. Box 8923
     New Fairfield, CT  06812-1783
     [phone]

     The National Arthritis and Musculoskeletal and Skin Diseases Information
     Clearinghouse
     Box AMS
     Bethesda, MD  20892
     [phone]

     Research Trust for Metabolic Diseases in Children
     Golden Gates Lodge, Weston Rd.
     Crewe CW1 1XN, England
     Telephone:  [phone]


For information on genetics and genetic counseling referrals, please
contact:

     March of Dimes Birth Defects Foundation
     1275 Mamaroneck Avenue
     White Plains, NY  10605
     [phone]

     Alliance of Genetic Support Groups
     35 Wisconsin Circle, Suite 440
     Chevy Chase, MD  20815
     (800) 336-GENE
     [phone]

     The Paget's Disease Foundation, Inc.
     (and other diseases of bone resorption)
     200 Varick St., Suite 1004
     New York, NY  10014-4810
     [phone]
     (800) 23-PAGET

References

JUVENILE OSTEOPETROSIS:  EFFECTS ON BLOOD AND BONE OF PREDNISONE AND A LOW
CALCIUM, HIGH PHOSPHATE DIET:  L.M. Dorantes, et. al.; Arch Dis Child (July
1986, issue 61(7)).  Pp. 666-670.

BONE MARROW TRANSPLANTATION:  RESEARCH REPORT;  U.S. Dept. of Health and
Human Services, National Cancer Institute.  (September 1986, NIH publication
No. 86-1178).