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$Unique_ID{BRK03920}
$Pretitle{}
$Title{Leber's Congenital Amaurosis}
$Subject{Leber's Congenital Amaurosis LCA Leber's Amaurosis Congenital Retinal
Blindness Congenital Retinitis Pigmentosa Leber's Congenital Tapetoretinal
Degeneration Dysplasia Congenital Absence of the Rods and Cones Retinitis
Pigmentosa Congenital Stationary Night Blindness Macular Degeneration Flecked
Retina Syndrome }
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Copyright (C) 1986, 1987, 1990 National Organization for Rare Disorders, Inc.

308:
Leber's Congenital Amaurosis

** IMPORTANT **
It is possible that the main title of the article (Leber's Congenital
Amaurosis) is not the name you expected.  Please check the SYNONYM listing to
find the alternate names and disorder subdivisions covered by this article.

Synonyms

     LCA
     Leber's Amaurosis
     Congenital Retinal Blindness
     Congenital Retinitis Pigmentosa
     Leber's Congenital Tapetoretinal Degeneration or Dysplasia
     Congenital Absence of the Rods and Cones

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

     Retinitis Pigmentosa
     Congenital Stationary Night Blindness
     Macular Degeneration
     Flecked Retina 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.


Leber's Congenital Amaurosis (LCA) is a retinal hereditary disorder of
the eye.  It is characterized by blindness at birth, roving eye movements,
pupils that react poorly to light and dilate widely in the dark.

Symptoms

In Leber's Congenital Amaurosis (LCA) children are born with an absence of
light-gathering cells (rods and cones) of the retina.  A decrease in visual
responsiveness at birth is the first sign of the disease.  Often the eyes are
deeply set and the child will rub the eyes to stimulate the retina to produce
light (oculodigital stimulation).  Absence or reduction of the electrical
activity of the retina is always observed and is necessary for the diagnosis
of LCA.  This disorder is frequently associated with a family history of loss
of eye muscle coordination.

Causes

Leber's Congenital Amaurosis is believed to be inherited as a recessive
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 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.

Rarely, LCA has been inherited as a dominant trait.  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 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.

Leber's Congenital Amaurosis can be seen as part of systemic disorders;
for example, neurological dysfunction, kidney disease, and rarely chromosomal
imbalance.

Affected Population

Leber's Congenital Amaurosis (LCA) is a rare eye disease that affects males
and females in equal numbers.

Related Disorders

Symptoms of the following disorders can be similar to those of Leber's
Congenital Amaurosis.  Comparisons may be useful for a differential
diagnosis:

Retinitis Pigmentosa (RP) is one of a group of inherited vision disorders
causing degeneration of the retina.  Initially this causes reduced vision but
it can progress to blindness.  Retinitis Pigmentosa may also be associated
with other conditions such as deafness (Usher's Syndrome), central nervous
system disorders, metabolic disorders and chromosomal abnormalities.
Difficulty in seeing at night is usually the initial symptom of RP.  Onset of
symptoms usually first occur during young adulthood.  (For more information on
this disorder, choose "RP " as your search term in the Rare Disease
Database).

Congenital Stationary Night Blindness is a hereditary nonprogressive
disorder that begins in infancy.  The main symptom is limited vision in dim
light, but patients often have normal color perception and/or clearness of
central vision.  It may take between two and eight hours for the eyes of
affected individuals to adapt to darkness.  The inside back of the eye is
normal when examined by a doctor and the retinal vessels stand out with
clarity.  The optic disk (part of the optic nerve) is normal.  The electrical
activity is abnormal and is characteristic of this disease.

Macular Degeneration is a more common hereditary eye (retinal) disorder
with several subdivisions.  This progressive disorder is characterized by a
gradual loss of vision usually in both eyes.  Symptoms of the various forms
of Macular Degeneration may overlap with those of other degenerative retinal
disorders.  The primary symptoms of macular degeneration include perception
of unclear shapes and blind spots within the field of vision.  (For more
information on this disorder, choose "Macular Degeneration" as your search
term in the Rare Disease Database).

Flecked Retina Syndrome is characterized by reduced clear vision and loss
of night vision in some cases.  To an ophthalmologist, the area behind the
retinal vessels appears marked with white or yellow flecks.  These flecks are
similar to those found in persons with Leber's Congenital Amaurosis, but the
retina is free from the abnormal markings characteristic of Leber's.  The
macula, retinal and choroidal vessels are usually not affected by this
genetic disorder.

Therapies:  Standard

Treatment of Leber's Congenital Amaurosis is symptomatic and supportive.
Standard procedures such as genetic counseling, and services that benefit the
sight impaired, can be helpful.

Therapies:  Investigational

Researchers at the Cullen Eye Institute of the Baylor College of Medicine in
Houston, TX, and The Hospital For Sick Children in Toronto, Canada are
studying a group of inherited retinal disorders including Leber's Congenital
Amaurosis.  Families with at least two affected members whose parents are
both living are needed to participate in the program.  In Toronto, isolated
cases are also being studied by DNA methods.  For more information, please
contact:

     Richard A. Lewis, M.D.
     Cullen Eye Institute
     Department of Ophthalmology
     Baylor College of Medicine
     One Baylor Plaza
     6501 Fannin Street
     Houston, TX 77030
     [phone]

     Maria A. Musarella, M.D.
     F.R.C.S. (C)
     Hospital For Sick Children
     Research Institute
     555 University Avenue
     Toronto, Ontario, Canada
     M5G 1x8

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 Leber's Congenital Amaurosis, please contact:

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

     NIH/National Eye Institute
     9000 Rockville Pike
     Bethesda, MD  20892
     [phone]

     RP Foundation fighting Blindness
     1401 Mt. Royal Avenue, 4th Floor
     Baltimore, MD 21217
     [phone]
     [phone]
     TDD [phone] (for the deaf)

     National Association for the Parents of the Visually Impaired, Inc.
     (NAPVI)
     P.O. Box 180806
     Austin, Texas 78718
     [phone]

     National Association for the Visually Handicapped
     305 East 24th Street
     New York, NY 10010
     [phone]

     American Foundation for the Blind (AFB)
     1010 Vermont Ave., NW, Suite 1100
     New York, NY 10011
     [phone]

     Richard A. Lewis, M.D.
     Cullen Eye Institute
     Department of Ophthalmology
     Baylor College of Medicine
     One Baylor Plaza
     6501 Fannin Street
     Houston, TX 77030
     [phone]

     Maria A. Musarella, M.D.
     F.R.C.S. (C)
     Hospital For Sick Children
     Research Institute
     555 University Avenue
     Toronto, Ontario, Canada
     M5G 1x8
     [phone] or [phone]

For genetic information 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]

References

LEBER'S CONGENITAL AMAUROSIS.  IS MENTAL RETARDATION A FREQUENT ASSOCIATED
DEFECT?  B. Nickel, et al.; Arch Ophthalmol (July, 1982, issue 100 (7)).  Pp.
1089-1092.

AMAUROSIS CONGENITA (LEBER), T. Hirose, et al,; Ann Aphthalmos (January,
1975, issue 7 (1)).  Pp. 59-63.

LEBER'S CONGENITAL AMAUROSIS. K. Mizuno, et al.; Am J Ophthalmol
(January, 1977, issue 83 (1)).  Pp. 32-42.