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$Unique_ID{BRK04178}
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$Title{Retinoblastoma}
$Subject{Retinoblastoma Retina Glioma }
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Copyright (C) 1986, 1987, 1990 National Organization for Rare Disorders, Inc.

289:
Retinoblastoma

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

Synonyms

     Retina, Glioma

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.


Retinoblastoma is a very rare, congenital malignant tumor that develops
in nerve cell layers of the eye.

Symptoms

Retinoblastoma is usually diagnosed before the age of 2 years when the eyes
squint or cross (strabismus), or when a gray to yellow reflex from the pupil
("cat's eye") is investigated.  Both eyes must be carefully investigated
ophthalmoscopically with the pupils widely dilated.

The tumors appear to the examining physician as gray-yellow elevations on
the retina.  The beginning of tumors (tumor "seeds") may be visible in the
vitreous body of the eye.  In some, calcification in the tumors can be
detected radiographically, especially with a CT scan.

Causes

Although most Retinoblastomas appear sporadically, about 20% are transmitted
as an autosomal dominant trait with incomplete penetrance.  (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 dominant disorders, a single copy of the disease gene (received
from either the mother or father) will be expressed "dominating" the normal
gene and resulting in appearance of the disease.  The risk of transmitting
the disorder from affected parent to offspring is 50% for each pregnancy
regardless of the sex of the resulting child.)  "Incomplete penetrance" means
that the severity of the disorder is determined by the degree to which the
defect has produced abnormalities.

Retinoblastoma occurs frequently in patients with D group chromosomal
abnormalities.

If a child inherits a gene predisposing it to get Retinoblastoma, a
second event must take place before Retinoblastoma occurs.  The nature of
this second event is unknown, but research is underway to determine which
factors (e.g. environmental triggers such as a virus) can precipitate onset
of this disorder.

Recently, scientists isolated a gene (on chromosome number 13) that
appears to prevent retinoblastoma.  Researchers have cloned or pinpointed the
first of a class of genetic switches, called recessive oncogenes, that
normally keep cancer from occurring.

Experts believe there are two kinds of oncogenes:  those that cause
cancer by their presence, and those that cause it by their absence.  Both
types are mutant or incomplete versions of ordinary genes that normally
regulate cell growth.  One kind is dominant and causes out-of-control growth
(cancer).  Recessive oncogenes normally limit or stop the growth of cells.
When they are lost, cells can proliferate wildly, causing cancer.  When the
normal gene is present, they appear to prevent cancer from developing.  This
genetic discovery is potentially very important in the understanding of many
types of cancer.

Affected Population

Retinoblastoma occurs in one in every 15,000 to 30,000 live births.  It
represents about 2% of childhood malignancies.  It occurs in both eyes in
about 30% of cases.

Children face a high risk of getting rare forms of bone cancer
(osteosarcoma) and eye cancer (retinoblastoma) if, through some inherited
mix-up, they are born without a complete copy of a certain type of gene,
called recessive oncogene.  Retinoblastoma is the most common form of eye
cancer in children, affecting approximately five hundred children in the
United States.  Because the same gene is involved in both disorders,
youngsters who get retinoblastoma appear to be susceptible to osteosarcoma.

Therapies:  Standard

When Retinoblastoma occurs in one eye, it is usually managed by excision of
the tumor and eye (enucleation) and removal of some of the optic nerve.  In
cases where both eyes are affected, the more involved eye often is enucleated
and the other eye may be treated by photocoagulation, cold therapy
(cryotherapy), radiation, or systemic antimetabolites.  Often a combination
of these treatments is used.  Ophthalmological reexamination of both eyes is
usually required at about 2-month intervals.  Radiologic surveys for bony
metastases and studies of spinal fluid and bone marrow for malignant cells,
may be conducted until all viable tumor is destroyed.  Siblings and other
family members should also be examined.

Therapies:  Investigational

Genetic probes (synthetic genes) that seek out their natural counterparts in
human genetic material, can locate individual genes within the 50,000 to
100,000 human genes that control the human body's functions.  Currently such
probes are being used experimentally on newborn babies who may be genetically
predisposed to Retinoblastoma.  This procedure may lead to earlier diagnosis,
and perhaps help to determine which factors serve to precipitate onset of the
disorder in genetically susceptible children.

This disease entry is based upon medical information available through
April 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 Retinoblastoma, please contact:

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

     New England Retinoblastoma Support Group
     603 Fourth Range Rd.
     Pembroke, NH  03275
     [phone]

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

     American Cancer Society
     1599 Clifton Rd., NE
     Atlanta, GA  30329
     [phone]

     NIH/National Cancer Institute
     9000 Rockville Pike, Bldg. 31, Rm. 1A2A
     Bethesda, MD 20892
     1-800-4-CANCER

The National Cancer Institute has developed PDQ (Physician Data Query), a
computerized database designed to give doctors quick and easy access to many
types of information vital to treating patients with this and many other
types of cancer.  To gain access to this service, a doctor can contact the
Cancer Information Service offices at 1-800-4-CANCER.  Information
specialists at this toll-free number can answer questions about cancer
prevention, diagnosis, and treatment.

For information on genetics 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

RETINOBLASTOMA AND CANCER GENETICS (Editorial); F. Gilbert:  New England
Journal of Medicine, 314 (19):  May 5, 1986.  Pp. 1248-9.