CD-ROM Today (UK) (Spanish) 15/CDRT.iso/dp/0375/03752.txt

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$Unique_ID{BRK03752}
$Pretitle{}
$Title{Fragile X Syndrome}
$Subject{Fragile X Syndrome X-linked Mental Retardation and Macroorchidism
Marker X Syndrome Fraxa Martin-Bell Syndrome Repenning Syndrome Autism}
$Volume{}
$Log{}

Copyright (C) 1988, 1989, 1990, 1991 National Organization for Rare
Disorders, Inc.

586:
Fragile X Syndrome

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

Synonyms

     X-linked Mental Retardation and Macroorchidism
     Marker X Syndrome
     Fraxa
     Martin-Bell Syndrome

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

     Repenning Syndrome
     Autism

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.


Fragile X Syndrome is a defect of the X chromosome which causes mild
mental retardation.  The disorder occurs more frequently and severely among
males than females.  This condition is the leading known familial cause of
mental retardation in the U.S.  Language delays, behavioral problems, autism
or autistic-like behavior (including poor eye contact and hand-flapping),
enlarged external genitalia (macroorchidism), large or prominent ears,
hyperactivity, delayed motor development and/or poor sensory skills are among
the wide range of symptoms associated with this disorder.

Symptoms

Fragile X Syndrome is characterized by connective tissue abnormalities such
as joints which may be extended beyond normal limits (hyperextensible) and
heart problems including mitral valve prolapse.  Flat feet, large external
genitalia (macroorchidism), large ears, and/or frequent ear infections
(otitis media) also occur.  Additionally, low muscle tone, a long narrow
face, high arched palate, dental problems and an inability of the eyes to
look in the same direction (strabismus) are common characteristics.  Delayed
motor development, hyperactivity, behavior problems, toe walking, and/or
occasional seizures can also occur in some patients.  Autism (a neurological
behavior disorder) or autistic like behavior may include poor eye contact,
hand flapping, and/or self-stimulating behaviors.  (For more information
about Autism, please choose "Autism" as your search term in the Rare Disease
Database.)

Poor sensory skills and mathematical ability are sometimes found in
conjunction with good reading skills.  Speech and language problems can
include automatic repetition of words or phrases (echolalia), inability to
mentally move from one idea to another (perseveration), poor language
content, and/or dropping of letters or syllables when speaking (cluttering).
The I.Q. of people with this disorder is generally lower than normal,
although some people may have average intelligence.

Causes

Fragile X Syndrome tends to affect babies born to women later in life,
usually past the age of 35.  The condition results from a breakdown of
certain areas on the X chromosome.  Males have only one X chromosome while
females have two.  Therefore, when an X chromosome in a female is affected by
this syndrome, the normal X chromosome can compensate for the defect, while
males tend to have the more severe form of the disorder.  In 1991 scientists
discovered the gene on the X chromosome that results in Fragile X Syndrome.
Researchers are hopeful that this will soon lead to genetic testing for the
defect.

Affected Population

Fragile X Syndrome occurs with more frequency and severity among males than
females.  In 1986, scientists estimated that one in 981 males and one in 677
females have the fragile X Chromosome.  Some of these people do not have
symptoms, and many are only mildly mentally retarded.

Related Disorders

Symptoms of the following disorders can be similar to those of Fragile X
Syndrome.  Comparisons may be useful for a differential diagnosis:

Renpenning Syndrome is a form of inherited X-linked mental retardation
due to the presence of the genetic defect at a different site than that of
Fragile X Syndrome (marXq28).  This disorder occurs more frequently in males,
although some females may also be affected.

The following disorder may be associated with Fragile X Syndrome as a
secondary characteristic.  It is not necessary for a differential diagnosis:

Autism is a lifelong neurological disorder characterized by onset before
thirty months of age, retarded development of communication and language and
lack of normal response to people.  About seventy-five percent of Autistic
children have lower than normal IQ's.  Occasionally, an Autistic child shows
distinct and unusual skills in music, mathematics, or in using spatial
concepts.  Autistic people live a normal life span.  The prognosis for normal
adaptation appears to vary with the level of functioning, intelligence and
the educational methods applied.  About 5 in 10,000 children have the fully
expressed syndrome; 15 in 10,000 children show 2 or more of the main
characteristics of autism.  Boys are affected four times more frequently than
girls.  (For more information on Autism, please choose "Autism" as your
search term in the Rare Disease Database.)

Therapies:  Standard

Treatment of Fragile X Syndrome includes special education, speech,
occupational, and sensory integration training, and behavior modification
programs.  Genetic counseling will be of benefit for families.  Other
treatment is symptomatic and supportive.  Surgical correction of heart
defects may sometimes be necessary.

Therapies:  Investigational

Folic acid has been found to improve hyperactivity and attention deficits in
some pre-adolescent males with Fragile X Syndrome.  However, further study of
this treatment is warranted to determine long-term benefits and possible side
effects.

Families with children who have the Fragile X chromosome are asked to
contact Valerie Simon, Michael Reiss, M.D., and Lisa Freund, Ph.D. at the
address below to participate in clinical research.  Female children are
especially needed.

     Valerie Simon, Michael Reiss, M.D., and Lisa Freund, Ph.D.
     The Kennedy Institute
     Behavioral Genetics Unit, Room 103
     707 North Broadway Ave.
     Baltimore, MD  21205
     [phone] or [phone] (collect)

This disease entry is based upon medical information available through
June 1991.  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 Fragile X Syndrome, please contact:

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

     Fragile X Foundation
     P.O. Box 300233
     Denver, CO  80220

     Fragile X Association of Michigan
     1786 Edinborough Dr.
     Rochester Hills, MI  48064
     [phone]

     Fragile X Syndrome Support Group
     P.O. Box 3177
     Camden, NJ  08181

     Institute for Basic Research in Developmental Disabilities
     1050 Forest Hill Road
     Staten Island, NY  10314
     [phone]

     NIH/National Institute of Child Health & Human Development (NICHHD)
     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]

References

GENETICS AND EXPRESSION OF THE FRAGILE X SYNDROME:  W.T. Brown, et al.; Ups J
Med Sci [Suppl]  (1986, issue 44).  Pp. 137-154.

FOLIC ACID AS AN ADJUNCT IN THE TREATMENT OF CHILDREN WITH THE AUTISM
FRAGILE-X SYNDROME (AFRAX):  C. Gillberg, et al.; Dev Med Child Neurol
(October 1986, issue 28(5) ).  Pp. 624-627.

MENDELIAN INHERITANCE IN MAN, 7th ed.:  Victor A. McKusick; Johns Hopkins
University Press, 1986.  Pp. 1418-1421.