CD-ROM Today 1996 January/CD-ROM Today 1996 January.iso/dp/0360/03602.txt

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$Title{Chromosome 9 Ring}
$Subject{Chromosome 9 Ring Ring 9 Ring 9 Chromosome Chromosomal Disorders}
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Copyright (C) 1993 National Organization for Rare Disorders, Inc.

952:
Chromosome 9 Ring

** IMPORTANT **
It is possible that the main title of the article (Chromosome 9 Ring) is
not the name you expected.  Please check the SYNONYMS listing to find the
alternate name and disorder subdivisions covered by this article.

Synonyms

     Ring 9
     Ring 9, Chromosome

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

     Chromosomal Disorders

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.

Chromosome 9 Ring is a rare chromosomal disorder in which the patient has
a breakage of chromosome 9 at both ends, and the ends of the chromosome join
together to form a ring.  The amount of genetic material lost at the two ends
of the chromosome can vary.  As a result, an affected individual with very
little absent genetic material may have no apparent symptoms, while a patient
with a significant part of the chromosomal ends missing may have more severe
symptoms.  Symptoms of this disorder may include unusual facial features,
heart defects, moderate to severe mental retardation, and skeletal
abnormalities.

Symptoms

Chromosome 9 Ring is a rare chromosomal disorder in which the symptoms depend
on the amount of genetic material lost on the small and long arms (ends) of
the 9th chromosome.  As a result, patients symptoms can very greatly.  Some
patients with Chromosome 9 Ring have very mild symptoms while others may be
more severely affected.

The symptoms of this chromosomal abnormality are often very mild.  Facial
abnormalities may include a small head (microcephaly), a triangular shaped
forehead (trigonocephaly), eyes that are downslanting and protrude outward,
an exaggerated arch to the eyebrows, a small chin and/or a short neck.  Heart
defects, as well as skeletal abnormalities including cleft palate, have been
seen in some affected individuals.  (For more information choose "Cleft
Palate" as your search term in the Rare Disease Database).

A few affected males may have abnormal external genitalia and/or an
abnormal urinary opening located on the underside of the penis (hypospadias).

Mental retardation can vary from very mild to severe.  Some affected
individuals may become agitated easily or they may be very shy and withdrawn.

Causes

Chromosome 9 Ring is a chromosomal disorder caused by a deletion of
Chromosome 9 at both ends and the joining of the ends to form a ring.  The
amount of genetic material lost from the ends can vary from a small amount
causing few symptoms to a significant amount causing many symptoms.  There is
no apparent reason why this occurs.  Most chromosomal deletions occur "de
novo" which means that they occur very early in the development of the
embryo.  The parents of the affected child typically have normal chromosomes
and a very low possibility of having another child with a chromosomal
abnormality.

A parent may have Chromosome 9 Ring with few apparent symptoms.  When
this is the case, the parent may transmit the chromosomal abnormality to the
child.  In these cases the affected parent has a fifty percent chance of
having another child with Chromosome 9 Ring.

Affected Population

Chromosome 9 Ring is a very rare chromosomal abnormality that affects males
and females equally.  There have been approximately twelve cases of this
disorder reported in the medical literature, although there may be several
hundred unreported cases.

Related Disorders

Symptoms of the following disorders can be similar to those of Chromosome 9
Ring.  Comparisons may be useful for a differential diagnosis:

Many chromosomal disorders involving mental retardation have some
features similar to Chromosome 9 Ring.  The only way to determine which
chromosomal abnormality an affected person has is through genetic testing.
(For more information choose "Mental Retardation and "chromosomal disorder"
as your search term in the Rare Disease Database.)

Therapies:  Standard

Special education and related services will be beneficial to children with
Chromosome 9 Ring.  In cases where cleft palate occurs, surgical treatment
and speech therapy may be warranted.  (For more information on the treatment
of cleft palate, choose "Cleft Palate" as your search term in the Rare
Disease Database).

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

Therapies:  Investigational

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 birth defects in the future.

This disease entry is based upon medical information available through
June 1993.  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 Chromosome 9 Ring, please contact:

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

     Chromosome Deletion Outreach
     P.O. Box 164
     Holtsville, NY  11742
     [phone]

     Association for Retarded Citizens of the U.S.
     P.O. Box 6109
     Arlington, TX  76005
     [phone]
     [phone]

     American Cleft Palate Cranial Facial Association
     1218 Granview Ave.
     Pittsburgh, PA 15211
     [phone]
     (800) 24CLEFT

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]

References

BIRTH DEFECTS ENCYCLOPEDIA, Mary Louise Buyse, M.D., Editor-In-Chief;
Blackwell Scientific Publications, 1990.  P. 354.

APPARENT PRADER-WILLI PHENOTYPE IN A WOMAN WITH RING CHROMOSOME 9:  R.O.
Hess, et al., Am J Med Genet Suppl (1987, issue 3).  Pp. 133-8.

RING CHROMOSOME 9.  CASE REPORT AND REVIEW OF THE LITERATURE:  S.
Manouvrier-Hanu et al.; Ann Genet (1988, issue 31(4)).  Pp.  250-3.