CD-ROM Today 1996 January/CD-ROM Today 1996 January.iso/dp/0429/04290.txt

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$Unique_ID{BRK04290}
$Pretitle{}
$Title{Trisomy}
$Subject{Trisomy Chromosomal Triplication Trisomy 6p, Partial Trisomy 8
Trisomy 9p Trisomy 10q Trisomy 13 Syndrome (Patau's Syndrome) Trisomy 18
Syndrome (Edward's Syndrome) Trisomy 21 Syndrome (Down Syndrome) Trisomy 22,
Partial (Cat-Eye Syndrome) }
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Copyright (C) 1987, 1990 National Organization for Rare Disorders, Inc.

429:
Trisomy

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

Synonyms

     Chromosomal Triplication

There are many different types of trisomies which are usually identified
by numbers and letters.  This entry contains information on the following
specific trisomies:

     Trisomy 6p, Partial
     Trisomy 8
     Trisomy 9p
     Trisomy 10q
     Trisomy 13 Syndrome (Patau's Syndrome)
     Trisomy 18 Syndrome (Edward's Syndrome)
     Trisomy 21 Syndrome (Down Syndrome)
     Trisomy 22, Partial (Cat-Eye 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.

Trisomies are very rare genetic disorders characterized by a chromosome
aberration.  Chromosomes are found in the nucleus of all body cells.  They
carry the genetic characteristics of each individual.  Pairs of human
chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X
and Y chromosomes for males, and two X chromosomes for females.  People with
a Trisomy have an extra chromosome added to one of the normal pairs.  Each
chromosome has a short arm which is designated "p", and a long arm identified
by the letter "q".  The triplication of the chromosome may be partial; i.e.
either an extra short arm or an extra long arm is present.  Defects are
classified by the name of the abnormal chromosome pair and which portion of
the chromosome is affected.  For example, 22p+ means that there is an extra
short arm added to the 22nd pair of chromosomes.

In general, the most common symptom of the trisomies is mental
retardation.

Symptoms

Trisomies are often characterized by mental retardation.  Following is a
description of a few trisomy disorders:

PARTIAL TRISOMY 6p:  This disorder is characterized by a triplicated
section of the short arm of the 6th chromosome.  Mental retardation, multiple
facial abnormalities as well as malformations of the lungs, kidney and the
presence of two kidneys on one side of the body with crossed ureters may
occur.

TRISOMY 8:  Patients with this form of Trisomy are often slender and of
normal height.  The ears are low-set and malformed, and the eyes tend to be
slanted down.  Bone and joint abnormalities may involve the ribs, spine and
kneecaps; joint contractures with poor range of motion are frequent.
Unusually deep creases in the palms and the soles of the feet are evident.
There is mild to moderate mental and motor retardation, often with delayed
and hard to understand speech.  Most of the patients are chromosomal mosaics,
(i.e., they have two or more cell types that have different numbers of
chromosomes).

TRISOMY 9p is identified by an extra short arm of the 9th chromosome.
This disorder is characterized by abnormalities in the hands, feet, and
pelvic bones.  The pattern of bone structures in X-rays of patients with
Trisomy 9p appears to be unique among patients with chromosomal
abnormalities.  Other symptoms include down-turned corners of the mouth, a
large rounded nose, slightly wide and deep-set slanted eyes, unusual
fingerprints and mental retardation.

TRISOMY 10q:  This type of Trisomy is characterized by a triplication of
part of the long arm of the 10th chromosome.  The predominant symptoms of
this disorder include a long head (dolichocephaly), prominent forehead, and
abnormally open seams and soft spots (fontanelles) on the skull at birth.  A
broad nose, cleft lip and palate, clubfoot, and cysts in the kidney may also
occur.

TRISOMY 13 SYNDROME (PATAU'S SYNDROME) is a genetic disorder which occurs
in approximately 1 in 5,000 live births.  It is characterized by midline
abnormalities, gross defects of the brain, mental retardation, and cleft lip
and/or cleft palate in most cases.  (For more information on this disorder,
choose  "Trisomy 13" as your search term in the Rare Disease Database.)

TRISOMY 18 SYNDROME (EDWARDS' SYNDROME) is a genetic disorder with onset
before birth.  Paternal and maternal age are usually higher than average.
Babies appear thin and frail.  They fail to thrive and have difficulty
feeding.  These children show generalized increased muscle tension
(hypertonicity) with rigidity in flexion of the limbs, and mental
retardation.  (For more information on this disorder, choose "Trisomy 18" in
the Rare Disease Database.)

PARTIAL TRISOMY 22 (CAT-EYE SYNDROME) is characterized by a congenital
absence or defect of certain eye tissue called coloboma, and the lack of an
opening for the anus (atresia).  Severe mental and physical retardation,
wide-set slanted eyes, small skin appendages (tags) or openings to the inside
of the mouth (fistulas) in front of the ears may develop.  Congenital heart
disease may also occur.  Full trisomy has been reported in a few patients
with similar symptoms, but a small jaw and low muscle tone (hypotonia)
distinguishes them from the partial Trisomy.

TRISOMY 21, also known as DOWN SYNDROME is the most prevalent and readily
identifiable genetic condition associated with mental retardation.  The extra
chromosome 21 changes the orderly development of body and brain.  (For more
information on this disorder, choose "Down" as your search term in the Rare
Disease Database.)

Causes

The Trisomies are inborn abnormalities of the chromosomes.  In some cases the
chromosome abnormalities are related to advanced maternal or paternal age.
Some genetic counselors suggest that pregnant women over the age of 35 should
undergo amniocentesis to rule out these birth defects.

Affected Population

Most Trisomies are very rare disorders that affect patients from birth.  Some
Trisomies might affect a few hundred or a few thousand children per year;
some may affect only a handful of children in the United States.  The most
common Trisomy is Down Syndrome (Trisomy 21 Syndrome) affecting approximately
7,000 newborn infants each year.  (For more information, choose "Down
Syndrome" as your search term in the Rare Disease Database.)

Related Disorders

There are many possible Trisomy disorders with a wide range of symptoms.
There are many causes of mental retardation, most of which are genetic
anomalies which are not trisomies.

Therapies:  Standard

Children with mental retardation associated with Down Syndrome (Trisomy 21)
usually benefit from early intervention programs and special education.
Parent and infant education can begin immediately after birth.  The
individual child should receive direct service programming to develop
learning, language, mobility, self-care and socialization skills.  Toddler
and preschool programs can further enhance the acquisition of skills to
enable people with mental retardation to reach their maximum potential.

Genetic counseling will be helpful to families of patients with a Trisomy
disorder.  Women over the age of 35 who are planning to have children may
wish to undergo amniocentesis since many trisomies can be detected before
birth.

Therapies:  Investigational

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 Trisomy, please contact:

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

     Support Organization for Trisomy 18/13 (SOFT 18/13)
     National Headquarters
     4625 Lindell Blvd., Suite 501
     St. Louis, MO  63108
     [phone]

     Trisomy 9p Support Group
     160 Locket Rd.
     Harrow Weald, Middlesex, Scotland, HA3 7NZ

     Contact Group for Trisomy 9P
     11 Durgoyne Drive
     Bearsden
     Glasgow, Scotland


     S.O.F.T. Canada Inc.
     1214 Concession 5 West
     RR 2 Waterdown, Ontario LOR 2H2
     [phone]

     Association for Retarded Citizens of the U.S.
     P.O. Box 6109
     Arlington, TX  76005
     [phone]
     1-800-433-5255

     National Down Syndrome Congress
     1640 West Roosevelt Road
     Chicago, IL  60608
     [phone]
     [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

RED BLOOD CELL GLUCOSE METABOLISM IN TRISOMY 10p:  POSSIBLE ROLE OF
HEXOKINASE IN THE ERYTHROCYTE:  M. Magnani, et al.; Blood (May 1983: issue
61,5).  Pp. 71-75.

TRISOMY 11p15 AND BECKWITH-WIEDEMANN SYNDROME.  REPORT OF TWO NEW CASES:
H. Journel, et al.; Annales Genet (Paris) (1985: issue 28,2).  Pp. 97-101.

MENDELIAN INHERITANCE IN MAN, 7th ed.:  Victor A. McKusick; Johns Hopkins
University Press, 1986.