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$Unique_ID{BRK03919}
$Pretitle{}
$Title{Laurence-Moon-Biedl Syndrome}
$Subject{Laurence-Moon-Biedl Syndrome Bardet-Biedl Syndrome Laurence-Biedl
Syndrome Laurence-Moon Syndrome Laurence-Moon-Bardet-Biedl Syndrome
Adipogenital-Retinitis Pigmentosa-Polydactyly Syndrome LMB Syndrome }
$Volume{}
$Log{}
Copyright (C) 1986, 1987, 1989, 1990 National Organization for Rare
Disorders, Inc.
104:
Laurence-Moon-Biedl Syndrome
** IMPORTANT **
It is possible that the main title of the article (Laurence-Moon-Biedl
Syndrome) is not the name you expected. Please check the SYNONYM listing to
find the alternate names and disorder subdivisions covered by this article.
Synonyms
Bardet-Biedl Syndrome
Laurence-Biedl Syndrome
Laurence-Moon Syndrome
Laurence-Moon-Bardet-Biedl Syndrome
Adipogenital-Retinitis Pigmentosa-Polydactyly Syndrome
LMB 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.
Laurence-Moon-Biedl syndrome (LMB) is characterized by abnormalities of
the retina, often leading to blindness, mental retardation, delayed or absent
sexual maturation, obesity, and the presence of extra fingers or toes. Other
anomalies or illness, especially of the kidney, may accompany these features.
Almost 600 cases have been reported. Boys are affected twice as often as
girls. The disorder is hereditary. Some researchers feel that Laurence-
Moon-Bardet syndrome actually comprises two distinct syndromes, Laurence-Moon
and Bardet-Biedl; the similarities between them, however, warrant considering
them as one entity, at least until more information about how the various
features develop becomes available.
Symptoms
The cardinal characteristics of Laurence-Moon-Biedl Syndrome are retinitis
pigmentosa (a disorder of the pigmented, light sensitive layer of the eye),
mental retardation, hypogonadism (underdevelopment of the testes and
ovaries), obesity from childhood due an unusually good appetite, and
polydactyly (presence of extra digits). (For more information on retinitis
pigmentosa, choose "RP" as your search term in the Rare Disease Database.)
The earliest manifestations usually appear in childhood and include
evidence of mental retardation and diminished night vision. Central vision,
then peripheral vision deteriorate. Three quarters of LMB patients are blind
by their early twenties. Cataracts, strabismus, and unusually small eyes
also frequently occur. The other cardinal symptoms do not progress.
Associated with hypogonadism is delayed puberty and delayed development
of secondary sex characteristics such as body hair, facial hair and voice
changes in males, and breasts in females. Boys may have fat accumulations
resembling breasts, and fail to develop sperm. Girls may fail to develop
breasts or menstruate.
Various other abnormalities are found in some patients. Neuromuscular
abnormalities include ataxia, problems coordinating muscle movements,
paralysis of certain muscles, and rigidity or spasticity. There may be
diabetes and malformations of the skull or urogenital tract. Kidney disease
is common including abnormalities of renal structure, function, or both.
Very rarely, the individual has congenital heart defects.
LMB can be diagnosed if retinal degeneration and three of the other
cardinal features are present.
Causes
Laurence-Moon-Biedl Syndrome appears to be transmitted by one or two
autosomal recessive genes on the same chromosome. Hypogonadism may be due to
unresponsiveness of the gonads to sex hormones. The cause of the abnormal
appetite is not known, although obesity is often associated with delayed
sexual maturation.
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 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.
Related Disorders
Alstrom syndrome has similar symptoms, but there is no mental retardation,
and there are no extra fingers or toes; instead, the individual has nerve
deafness, baldness, and metabolic abnormalities. Weiss syndrome is
characterized by deafness, hypogonadism, obesity, and mental retardation.
Biemond II syndrome resembles LMB except that eye abnormalities consist of
anomalies of the iris rather than retinitis pigmentosa.
Prader-Willi syndrome is also characterized by hypogonadism, obesity, and
neurological and intellectual/behavioral abnormalities; it does not include
blindness, however. Hypogonadotropic hypogonadism and Froelich syndrome
similarly exhibit delayed sexual development and obesity, but not visual
problems.
Therapies: Standard
In Laurence-Moon-Biedl Syndrome, the testes do not seem to respond to sex
hormones; thus, stimulation with gonadotropic hormones does not seem to be a
useful treatment. Abnormalities of the hands and feet may be corrected
surgically if desired. Where blindness is not complete, visual aids may be
useful. The appetite may be difficult to manage, but a strictly controlled
diet helps reduce weight.
Therapies: Investigational
Researchers at the Cullen Eye Institute of the Baylor College of Medicine in
Houston, Texas are studying inherited retinal diseases including Laurence-
Moon-Biedl Syndrome. Families with at least two affected members and both
parents living are needed to participate in this program. Other disorders
being included in the study are Leber's Congenital Amaurosis, Usher Syndrome
(Types I and II), Macular Degeneration and Polymorphic Macular Degeneration,
and Rod Monochromacy (Complete Congenital Achromatopsia).
Other inherited retinal disorders of interest include blue cone
monochromacy (Congenital Incomplete X-linked Achromatopsia), Choroideremia,
the Oculo-Cerebro-Renal Syndrome of Lowe, Hereditary X-linked cataracts, and
other hereditary diseases with significant visual impact.
This disease entry is based upon medical information available through
May 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 Laurence-Moon-Biedl Syndrome, please contact:
National Organization for Rare Disorders (NORD)
P.O. Box 8923
New Fairfield, CT 06812-1783
(203) 746-6518
Laurence-Moon-Biedl Support Network
76 Lincoln Ave.
Purchase, NY 10577
(914) 251-1163
NIH/National Institute of Child Health and Human Development
9000 Rockville Pike
Bethesda, MD 20892
(301) 496-5133
NIH/National Institute of Neurological Disorders & Stroke (NINDS)
9000 Rockville Pike
Bethesda, MD 20892
(301) 496-5751
(800) 352-9424
For services to blind people, please contact:
American Council of the Blind, Inc. (ACB)
1211 Connecticut Avenue, N.W., Suite 506
Washington, DC 20036
(202) 833-1251
(800) 424-8666
American Foundation for the Blind (AFB)
1010 Vermont Ave., NW, Suite 1100
New York, NY 10011
(202) 393-3666
American Printing House for the Blind
P.O. Box 6085
Louisville, KY 40206-0085
(502) 895-2405
National Association for Parents of the Visually Impaired (NAPVI)
3329 Northaven Road
Dallas, TX 75229
(214) 358-1995
National Library Service for the Blind and Physically Handicapped
Library of Congress
1291 Taylor Street, NW
Washington, DC 20542
(202) 287-5100
National Society to Prevent Blindness
79 Madison Avenue
New York, NY 10016
(212) 684-3505
Vision Foundation, Inc.
2 Mount Auburn Street
Watertown, MA 02172
(617) 926-4232
(800) 852-3029 (Toll-free in Mass.)
References
Bardet-Biedl syndrome and related disorders. Schachat, A.P. and Maumenee,
I.H. Arch Ophthalmol 1982 Feb; 100(2):285-8.
The Spectrum of Renal Disease in Laurence-Moon-Biedl Syndrome. J.D.
Harnett, et al.; New England Journal of Medicine, (September 8, 1988, Vol.
319, (10)). Pp. 615-618).