CD-ROM Today 1996 January/CD-ROM Today 1996 January.iso/dp/0417/04177.txt

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$Unique_ID{BRK04177}
$Pretitle{}
$Title{Retinitis Pigmentosa}
$Subject{Retinitis Pigmentosa RP Acanthocytosis Laurence-Moon-Biedl Syndrome
Choroideremia Refsum Syndrome Usher Syndrome }
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Copyright (C) 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1992 National
Organization for Rare Disorders, Inc.

21:
Retinitis Pigmentosa

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

Synonyms

     RP

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

     Acanthocytosis
     Laurence-Moon-Biedl Syndrome
     Choroideremia
     Refsum Syndrome
     Usher 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.


Retinitis Pigmentosa (RP) is one of a group of inherited visual disorders
that causes the degeneration of the retina of the eyes.  Vision gradually
decreases and may eventually be lost.  Retinitis Pigmentosa can be associated
with deafness and other malfunctions, central nervous system and metabolic
disorders, and chromosomal abnormalities.

Symptoms

Retinitis Pigmentosa usually begins as night blindness followed sometime
later by tunnel vision.  Symptoms are generally noticed between the age 10
and 40.  The rate and extent of progression are widely variable.  When other
members of a family are affected, the rates of progression are usually
similar within that family.

Some individuals with Retinitis Pigmentosa are also born deaf (Usher
syndrome Type I), or hearing-impaired (Usher syndrome Type II).  For more
information on Usher Syndrome, see the "Related Disorders" section of this
report.

Causes

Most cases of Retinitis Pigmentosa are isolated, but this disorder may be
inherited as a recessive, autosomal dominant, or X-linked genetic trait.  At
least 32 systemic disorders show some type of retinal involvement similar to
Retinitis Pigmentosa.

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 not show 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.

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.

X-linked recessive disorders are conditions which are coded on the X
chromosome.  Females have two X chromosomes, but males have one X chromosome
and one Y chromosome.  Therefore, in females, disease traits on the X
chromosome can be masked by the normal gene on the other X chromosome.  Since
males only have one X chromosome, if they inherit a gene for a disease
present on the X, it will be expressed.  Men with X-linked disorders transmit
the gene to all their daughters, who are carriers, but never to their sons.
Women who are carriers of an X-linked disorder have a fifty percent risk of
transmitting the carrier condition to their daughters, and a fifty percent
risk of transmitting the disease to their sons.

At least 32 systemic disorders show some type of retinal involvement
similar to Retinitis Pigmentosa.

In 1989, mutations on the long arm of chromosome 3 were shown to be
associated with 20 percent of families who have autosomal dominant Retinitis
Pigmentosa.

The gene responsible for early-onset autosomal dominant Retinitis
Pigmentosa is thought to be different from the gene that causes late-onset
Retinitis Pigmentosa.  It is hoped that this knowledge will lead to discovery
of chromosome markers or genes that cause other types of Retinitis
Pigmentosa.

Affected Population

Retinitis Pigmentosa affects 1 in 3,000 to 5,000 people in the United States.

Related Disorders

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

Acanthocytosis is an inherited blood disorder characterized by the
presence of malformed red blood cells (acanthocytes) in the circulating
blood.  This disorder usually begins in the first year of life and is
characterized by an impaired ability to coordinate movement (ataxia),
Retinitis Pigmentosa and the malabsorption of fat in the digestive system.
(For more information on this disorder, choose "Acanthocytosis" as your
search term in the Rare Disease Database).

Laurence-Moon-Biedl Syndrome is a rare disorder characterized by a
decrease in the efficiency of the testes or ovaries (hypogonadism), Retinitis
Pigmentosa (degeneration of the retina of the eyes), mental retardation, more
than the normal number of fingers (polydactyly), and obesity.  Obesity is one
of the earliest signs of this disorder.  (For more information on this
disorder, choose "Laurence-Moon-Biedl" as your search term in the Rare
Disease Database).

Choroideremia is an inherited vision disorder characterized by extensive
defects in the pigmented surface layer of cells in the eye (peripheral
retinal epithelium).  The major symptoms of this disorder include a
progressive loss of the central field of vision and night blindness during
childhood.  Choroideremia usually affects males; female carriers may have
mild symptoms without loss of vision.  (For more information on this
disorder, choose "Choroideremia" as your search term in the Rare Disease
Database).

Refsum Syndrome is a slowly progressive inherited disorder of fat (lipid)
metabolism that is characterized by the accumulation of phytanic acid in the
blood and tissues.  The four major features of this disorder are Retinitis
Pigmentosa, peripheral neuropathy, impaired ability to coordinate movement
(ataxia) and the elevation of protein in the cerebrospinal fluid.  (For more
information on this disorder, choose "Refsum Syndrome" as your search term in
the Rare Disease Database).

Usher Syndrome is a group of inherited disorders characterized by night
blindness and the loss of vision similar to that seen in Retinitis
Pigmentosa, in association with congenital hearing impairment.  This syndrome
is considered to be separate from other forms of Retinitis Pigmentosa.  The
two forms of Usher Syndrome are distinguished by the severity of the symptoms
and the age at onset.  (For more information on this disorder, choose "Usher
Syndrome" as your search term in the Rare Disease Database.)

Therapies:  Standard

Retinitis Pigmentosa has no cure at the present time.  In cases where
cataracts significantly interfere with vision, it may be advisable to remove
them surgically.  Whether or not surgery helps to improve vision often
depends on how far the retinal changes have advanced.

Various vision aids help people to make the maximum use of their
remaining vision.  The visual aids include optical aids such as Corning and
NOIR glasses, the Fresnel Prising telescopes, microscopes and night vision
devices.

There are other non-optical aids that may be useful for patients with
Retinitis Pigmentosa.  These include the Wide Angle Mobility Light, paper
guides, large print typewriters and adjustable stands.  The Apollo Laser and
Visualtek closed-circuit television may be of assistance in some cases.
There are also reading machines and talking computers that can enhance the
quality of life for those patients whose vision is severely impaired by
Retinitis Pigmentosa.

Affected relatives should be examined to determine the pattern of
inheritance, the basis for diagnosis, prognosis and genetic counseling.

Genetic counseling may be of benefit for patients and their families.
Other treatment is symptomatic and supportive.

Therapies:  Investigational

Researchers at the Cullen Eye Institute of the Baylor College of Medicine in
Houston, Texas are studying inherited retinal diseases including Usher
Syndrome (Types I and II).  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,
Macular Degeneration and Polymorphic Macular Degeneration, Laurence-Moon-
Biedl Syndrome, and Rod Monochromacy (Complete Congenital Achromatopsia).
Other inherited retinal disorders of interest to the Baylor researchers
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.

At the present time, scientists investigating the orphan drug Cronnassial
as a possible treatment for some symptoms of Retinitis Pigmentosa.
Physicians who would like more information on this treatment may contact:

     Fidia Pharmaceutical
     1775 K Street, NW
     Suite 800
     Washington, D.C.  20006

Research on birth defects and their causes is ongoing.  The National
Institutes of Health (NIH) is sponsoring the Human Genome Project which 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
September 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 Retinitis Pigmentosa, please contact:

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

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

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

For Genetic Information and Genetic Counseling Referrals:

     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]

For services to blind people, please contact:

     American Council of the Blind, Inc. (ACB)
     1211 Connecticut Avenue, N.W., Suite 506
     Washington, D.C.  20036
     [phone]
     [phone]

The American Council of the Blind is a national membership organization
dedicated to improving living conditions of the blind and visually impaired.
The council provides legal services and periodic training workshops, conducts
legislative activities, and maintains 16 occupational and special interest
affiliates, as well as 51 state affiliates.  Their monthly publication is
entitled "The Braille Forum."

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

American Foundation for the Blind provides information and services in
the areas of rehabilitation, orientation and mobility, employment, low
vision, legislative issues, aging, children and youth, radio information
services, recreation, education and research.  Many catalogs, informational
brochures are free.  The Foundation also publishes books, monographs and
periodicals in print, recording, and braille.  They manufacture and record
talking books as well as develop, manufacture and sell aids and appliances
for blind and visually impaired people.

     American Printing House for the Blind
     P.O. Box 6085
     Louisville, KY  40206-0085
     [phone]

The American Printing House for the Blind produces educational aids and
literature for the visually impaired, braille and talking book editions of
several magazines, braille books, music and large-type texts.  They also
manufacture special educational aids for the blind and visually impaired as
well as maintain a reference catalogue service for students.

     National Association for Parents of the Visually Impaired (NAPVI)
     3329 Northaven Road
     Dallas, TX  75229
     [phone]

The National Association of Parents of the Visually Impaired is a non-
profit membership organization comprised of agencies and parents dedicated to
providing support to families with children who have visual impairments.
They develop local and state groups and workshops.  They also function as a
national clearinghouse for information, referral and education.

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

     or

     3201 Balboa Street
     San Francisco, CA  94121
     [phone]

The National Association of Visually Handicapped is as association
providing youth and adult services, large print publishing, library services,
visual and audio information, public and professional education and special
services to senior citizens.  They also serve as an advocate for partially
sighted, and offer demonstration and pilot programs for youth in San
Francisco.  There are adult discussion and counseling programs in San
Francisco and New York, and a Career Planning/Job Seeking Workshop in New
York.

     National Federation of the Blind (NFB)
     1800 Johnson Street
     Baltimore, MD  21230
     [phone]
     [phone] (Job Opportunities for the Blind)

The National Federation of the Blind is a membership organization with
state and local chapters providing information concerning rights of the
blind, program development, and job opportunities for the Blind (an
employment placement and training program).  The Federation publishes "The
Braille Monitor" on a monthly basis as well as other publications.  Advocacy
and legal representation are provided through the Federation.  Local projects
are underway to improve conditions for visually impaired people.

     National Library Service for the Blind and Physically Handicapped
     Library of Congress
     1291 Taylor Street, NW
     Washington, DC  20542
     [phone]

The National Library Service for the Blind and Physically Handicapped
heads a national network of 160 cooperating libraries housing extensive
collections.  They lend braille books, talking books and magazines and also
publish regular catalogues which may be obtained as recorded audio tapes, as
large printed text, or in braille.  They also provide talking-book machines
and accessories as well as large print music and recorded music instructional
material.  All material is free on loan and no postage is required.  The user
must be certified by a professional authority as unable to read standard
print material because of visual or physical impairment.

     Recording for the Blind, Inc. (RFB)
     215 East 58th Street
     New York, NY  10022
     [phone]

Recording for the Blind provides recorded educational textbooks to
visually, physically and perceptually handicapped students at all grade
levels, and also to professionals.  There are over 58,000 titles in the
library catalogue.  This organization has 5,000 specially trained volunteers
and 28 recording centers.  Their services are free to medically certified
registered borrowers.

References

THE MERCK MANUAL 15th ed:  R. Berkow, et al:  eds; Merck, Sharp & Dohme
Research Laboratories, 1987.  Pp. 2234.

CECIL TEXTBOOK OF MEDICINE, 18th ed.:  James B. Wyngaarden, and Lloyd H.
Smith, Jr., Eds.:  W. B. Saunders Co., 1988.  Pp. 2236, 2292-3.

MENDELIAN INHERITANCE IN MAN, 10th Ed.:  Victor A. McKusick, Editor:
Johns Hopkins University Press, 1992.  Pp. 974-975.

BIRTH DEFECTS ENCYCLOPEDIA, Mary Louise Buyse, M.D., Editor-In-Chief;
Blackwell Scientific Publications, 1990.  Pp. 1485-1486.

CLINICAL OPHTHALMOLOGY, 2nd Ed.; Jack J. Kanski, Editor; Butterworth-
Heinemann, 1990.  Pp. 372-374.

MOLECULAR GENETICS OF RETINITIS PIGMENTOSA, D.B. Farber et al.; West J
Med (Oct 1991; 155(4)):  Pp. 388-399.

RETINITIS PIGMENTOSA, R.A. Pagon; Surv Ophthalmol (Nov-Dec 1988; 33(3)):
Pp. 137-177.