CD-ROM Today (UK) (Spanish) 15/CDRT.iso/dp/0341/03413.txt

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$Unique_ID{BRK03413}
$Pretitle{}
$Title{Achondroplasia}
$Subject{Achondroplasia Chondrodystrophy Chondrohystrophia Chondrodystrophia
Fetalis Hypoplastic Chondrodystrophy Parrot Syndrome Achondroplastic Dwarfism
Dwarfism}
$Volume{}
$Log{}

Copyright (C) 1986, 1990, 1992, 1993 National Organization for Rare
Disorders, Inc.

80:
Achondroplasia

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

Synonyms

     Chondrodystrophy
     Chondrohystrophia
     Chondrodystrophia Fetalis
     Hypoplastic Chondrodystrophy
     Parrot Syndrome
     Achondroplastic Dwarfism

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

     Dwarfism

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.


Achondroplasia is an inherited congenital disorder that results in very
short stature (dwarfism) due to an impairment in the ability of cartilage to
form bone (endochondral bone formation).  Craniofacial abnormalities are also
associated with Achondroplasia.

Symptoms

Infants born with Achondroplasia typically have an arched or "dome-like"
(vaulted) skull to adapt to the abnormally enlarged brain (megalencephaly)
that is characteristic in this syndrome.  This results in a very broad
forehead.  Excessive accumulation of fluid around the brain (hydrocephalus)
may also be present.  Compression of the brain stem may occur in some
children with Achondroplasia resulting in a life-threatening condition.  (For
more information on this disorder, choose "Hydrocephalus" as your search term
in the Rare Disease Database.)

Infants with Achondroplasia typically have a low nasal bridge.  Arms and
legs are usually very short and the trunk of the body appears long in
comparison.  The hands of children with this disorder are generally short and
broad.  The index and middle finger are typically close together as are the
ring finger and the pinkie, giving the hand a three pronged (trident)
appearance.  An abnormal condition of the spine characterized by the outward
(convex) curvature of the upper back (dorsal kyphosis) is usually present in
children with this disorder and their legs may be bowed.  Most adult males
with Achondroplasia are under 4 feet 6 inches tall, while females are
typically 3 inches shorter than males.

Children with Achondroplasia may also have deformities of the rib cage
including the excessive curvature or "cupping" of the ribs.  Achondroplasia
does not cause any impairment or deficiencies in mental abilities.  The life
expectancy of infants over the age of 12 months is normal.

Causes

Achondroplasia is inherited as an autosomal dominant genetic trait.  Human
traits, including the classic genetic diseases, are the product of the
interaction of two genes, 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 other
normal gene and resulting in the appearance of the disease.  The risk of
transmitting the disorder from affected parent to offspring is fifty percent
for each pregnancy regardless of the sex of the resulting child.

Children of fathers of advanced age are more likely to be born with a
spontaneous case (de novo mutation) of Achondroplasia.  In these cases the
Achondroplasia is not inherited through autosomal dominant genes, and the
exact cause is unknown.

Affected Population

Achondroplasia is a rare disorder that affects males and females in equal
numbers.  This disorder begins in the developing fetus (congenital) and is
one of the most common forms of skeletal dysplasia that causes dwarfism.
Approximately 5 to 15 newborns in 100,000 are affected by this disorder in
the United States.

Related Disorders

Symptoms of the following disorders can be similar to those of
Achondroplasia.  Comparisons may be useful for a differential diagnosis:

Dwarfism may be associated with many other disorders.  Some of these
include Diastrophic Dysplasia, Osteogenesis Imperfecta, Thanatophoric
Dysplasia, Hypochondroplasia, Constitutional Growth Delay, Growth Hormone
Delay, and Russell-Silver Syndrome.  Achondroplasia may be distinguished from
other forms of short-limbed stature through examination by a physician as
well as x-rays studies and/or magnetic resonance imaging.  Many forms of
dwarfism are not associated with an abnormally enlarged head or other
symptoms of Achondroplasia that are characteristic for the disorder.  (For
more information on these disorders, choose "Diastrophic Dysplasia,"
"Osteogenesis Imperfecta," "Thanatophoric Dysplasia," "Hypochondroplasia,"
"Constitutional Growth Delay," "Growth Hormone Delay," and "Russell-Silver"
as your search terms in the Rare Disease Database.)

Therapies:  Standard

Ultrasonography or magnetic resonance imaging (MRI) of the brain in infancy
may be done to determine the presence of hydrocephalus which is sometimes
associated with Achondroplasia.  Orthopedic surgery and physical therapy may
be beneficial in the management of this disorder.  Genetic counseling may
also be useful.

Little People of America is an organization providing social services for
persons with Achondroplasia.  The organization also acts as an advocate on
their behalf (see Resources Section of this report).

Therapies:  Investigational

The Titanium Rib Project is underway to implant expandable ribs in children
with disorders such as Achondroplasia and other disorders involving missing,
underdeveloped, or otherwise malformed rib cages, and/or chest walls.  Birth
defects, fused ribs, or hypoplastic chests may be improved using the titanium
ribs that can be expanded as the child grows.  More research is needed to
determine the long-term safety and effectiveness of these artificial ribs.
People who are interested may have their physicians contact:

     Dr. Robert Campbell
     Santa Rosa Children's Hospital
     519 W. Houston St.
     San Antonio, TX  78207-3198
     [phone]

Research on genetic defects and their causes is ongoing.  The National
Institutes of Health (NIH) is sponsoring the Human Genome Project that is
aimed at mapping every gene in the human body and learning why they sometimes
malfunction.  It is hoped that this new knowledge will lead to prevention and
treatment of genetic disorders in the future.

This disease entry is based upon medical information available through
May 1993.  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 Achondroplasia, please contact:

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

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

     Little People of America
     P.O. Box 633
     San Bruno, CA  94066
     [phone]

     International Center for Skeletal Dysplasia
     St. Joseph Hospital
     7620 York Rd.
     Towson, MD  21204
     [phone]

     Human Growth Foundation (HGF)
     7777 Leesburg Pike
     P.O. Box 3090
     Falls Church, VA  22043
     [phone]
     [phone]

     The Magic Foundation
     1327 N. Harlem Ave.
     Oak Park, IL  60302
     [phone]

     Short Stature Foundation
     17200 Jamboree Rd., Suite J
     Irvine, CA  92714-5828
     [phone]
     (800) 24-DWARF

     Parents of Dwarfed Children
     11524 Colt Terrace
     Silver Spring, MD 20902

     Association for Research into Restricted Growth
     2 Mount Court
     81 Central Hill
     London SE 19 1 BS
     England
     01-678-2984

For Genetic Information and Genetic Counseling Referrals:

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

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

References

SMITH'S RECOGNIZABLE PATTERNS OF HUMAN MALFORMATION, 4th ed., Kenneth L.
Jones, M.D., W.B. Saunders, Co. 1988.  Pp. 298-303.

MENDELIAN INHERITANCE IN MAN, 10th Ed.:  Victor A. McKusick, Editor:
Johns Hopkins University Press, 1992.  Pp. 10-11.

CECIL TEXTBOOK OF MEDICINE, 19th Ed.:  James B. Wyngaarden, and Lloyd H.
Smith, Jr., Editors; W.B. Saunders Co., 1990.  Pp. 1435-36.

THE MERCK MANUAL, 16th Ed.:  Robert Berkow Ed.; Merck Research
Laboratories, 1992.  Pp. 2255-2256.

BIRTH DEFECTS ENCYCLOPEDIA, Mary Louise Buyse, M.D., Editor-In-Chief;
Blackwell Scientific Publications, 1990.  Pp. 11-12.

NELSON TEXTBOOK OF PEDIATRICS, 14th Ed.; Richard E. Behrman et al; W.B.
Saunders Co., 1992.  Pp. 1733-34.

MAGNETIC RESONANCE IMAGING IN THE ASSESSMENT OF MEDULLARY COMPRESSION IN
ACHONDROPLASIA.  I.T. Thomas; Am J Dis Child (Sep 1988; 142(9)).  Pp. 989-992.

GROWTH HORMONE THERAPY IN ACHONDROPLASIA.  W.A. Horton; Am J Med Genet
(Mar 1992; 42(5)).  Pp. 667-70.