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$Unique_ID{BRK03917}
$Pretitle{}
$Title{Laron Dwarfism}
$Subject{Laron Dwarfism Pituitary Dwarfism II Laron Type Pituitary Dwarfism
LTD Growth Hormone Receptor Deficiency Growth Hormone Receptor GHR Growth
Hormone Binding Protein GHBP Coffin-Siris Syndrome Cockayne Syndrome }
$Volume{}
$Log{}
Copyright (C) 1990, 1992 National Organization for Rare Disorders, Inc.
821:
Laron Dwarfism
** IMPORTANT **
It is possible that the main title of the article (Laron Dwarfism) is
not the name you expected. Please check the SYNONYM listing to find the
alternate names and disorder subdivisions covered by this article.
Synonyms
Pituitary Dwarfism II
Laron Type Pituitary Dwarfism
LTD
Growth Hormone Receptor Deficiency
Growth Hormone Receptor
GHR
Growth Hormone Binding Protein
GHBP
Information on the following diseases can be found in the Related
Disorders section of this report:
Coffin-Siris Syndrome
Cockayne Syndrome
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.
Laron Dwarfism is a rare genetic disorder that results from the body's
inability to use the growth hormone that it produces. People with this
disorder produce normal levels of growth hormone but the levels in their
plasma may be high because the body does not use the hormone properly. The
Laron form of dwarfism is characterized by very small stature, peculiar
facial features, and high levels of growth hormone in plasma.
Symptoms
Laron Dwarfism is characterized by proportionate severe short stature which
is evident at birth or soon after. Along with growth retardation there are
delays in tooth eruption. There is also disproportion between the growth of
the head and jaw, a saddle nose and deep set eyes. Sexual development is
slow but it does occur. The usual age of sexual maturation in boys with
Laron Dwarfism is about 22 years of age. In females with the disorder sexual
maturation usually takes place between 16 to 19 years of age. Hands and feet
are smaller than normal. Obesity and a high-pitched voice may also be
present.
There are always high levels of growth hormone in the plasma of people
with Laron Dwarfism. A high percentage of patients have extremely low blood
sugar levels (Hypoglycemia) which can have very serious consequences if not
treated quickly by a doctor.
Causes
Laron Dwarfism is inherited as an autosomal recessive genetic disorder.
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 recessive disorders, the condition does not appear unless a person
inherits the same defective gene for the same trait 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.
The gene for Laron Dwarfism is thought by scientists to be located on
chromosome 5p 13.1-p12. The defect in this gene causes growth hormone
receptor defects which are not yet clearly understood. If growth hormone
receptors are abnormal, the body cannot use the hormone to grow. The
disorder may differ from family to family.
Affected Population
Laron Dwarfism affects six females to every two males. The disorder was
first recognized in persons of Middle Eastern Jewish ancestry and in
Mediterranean populations. However, Laron Dwarfism may occur in any ethnic
group. The disorder is usually evident at birth or shortly after.
Related Disorders
Symptoms of the following disorders can be similar to those of Laron
Dwarfism. Comparisons may be useful for a differential diagnosis:
Coffin-Siris Syndrome is a disorder of unknown cause. It is present at
birth and affects both sexes. It is chiefly characterized by feeding
problems, frequent respiratory infections, and growth deficiencies. (For
more information on this disorder, choose "Coffin-Siris" as your search term
in the Rare Disease Database).
Cockayne Syndrome is a progressive disorder which manifests itself during
the second year of life. It is characterized by a hypersensitivity to
sunlight and growth retardation. (For more information on this disorder,
choose "Cockayne" as your search term in the Rare Disease Database).
There are many disorders that can cause dwarfism. For more information
on those disorders choose "Dwarf" as your search term in the Rare Disease
Database or contact the Human Growth Foundation or the Short Stature
Foundation noted in the resources section of this report.
Therapies: Standard
Treatment of Laron Dwarfism with human growth hormone (HGH) is not effective
because the body cannot utilize the hormone to grow. If the patient has low
blood sugar (Hypoglycemia) this condition must be treated to prevent further
complications. Other treatment is symptomatic and supportive.
Genetic counseling may be of benefit for patients and their families.
Therapies: Investigational
The insulin-like growth factor 1, Somazom (somatomedin C), manuactured by
Fujisawa Pharmaceutical's, is being studied as a treatment for Laron-type
dwarfism. Early results are promising but further studies are necessary to
determine the long-term safety and effectiveness of this type of treatment.
Scientists continue their investigations into the causes and treatment of
short stature and dwarfism.
This disease entry is based upon medical information available through
July 1992. 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 Laron Dwarfism, please contact:
National Organization for Rare Disorders
P.O. Box 8923
New Fairfield, CT 06812-1783
(203) 746-6518
The Magic Foundation
1327 N. Harlem Ave.
Oak Park, IL 60302
(708) 383-0808
Human Growth Foundation
7777 Leesburg Pike
P.O.Box 3090
Falls Church, VA 22043
703-883-1773
800-451-6434
Short Stature Foundation
17200 Jamboree Rd., Suite J
Irvine, CA 92714-5828
(714) 474-4554
800-24 DWARF
Little People of America
P.O. Box 633
San Bruno, CA 94066
(415) 589-0695
NIH/The National Institute of Child Health and Human Development
9000 Rockville Pike
Bethesda, MD 20892
(301) 496-5133
For Genetic Information and genetic counseling referrals:
March of Dimes Birth Defects Foundation
1275 Mamaroneck Avenue
White Plains, NY 10605
(914) 428-7100
Alliance of Genetic Support Groups
35 Wisconsin Circle, Suite 440
Chevy Chase, MD 20815
(800) 336-GENE
(301) 652-5553
References
MENDELIAN INHERITANCE IN MAN, 9th ed.: Victor A. McKusick; Johns Hopkins
University Press, 1990. Pp. 1426-1427.
LARON DWARFISM AND MUTATIONS OF THE GROWTH HORMONE-RECEPTON GENE, Serge
Amelm, et al.; N Eng J Med. (October 12, 1989, issue 321 (15)). Pp. 1426-
1427.
RECEPTOR-ACTIVE GROWTH HORMONE IN LARON DWARFISM. L.S. Jacobs, J Clin
Endocrinol Metab, (February, 1976, issue 42 (2)). Pp. 403-406.
CHARACTERIZATION OF THE HUMAN GROWTH HORMONE RECEPTOR GENE AND
DEMONSTRATION OF A PARTIAL GENE DELETION IN TWO PATIENTS WITH LARON-TYPE
DWARFISM. P.J. Godowski, et al.; Proc Nat Acad Sci USA, (October, 1989,
issue 86 (20)). Pp. 8083-8087.
PUBERTY IN LARON TYPE DWARFISM. Z. Laron, et al.; Eur J Pediatr, (June,
1980, issue 134 (1)). Pp. 79-83.