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$Title{Klinefelter Syndrome}
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Copyright (C) 1986, 1990 National Organization for Rare Disorders, Inc.

96:
Klinefelter 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.

Klinefelter Syndrome, which is characterized by the presence of one or
more extra x-chromosomes in at least one tissue, is the most frequent cause
of primary hypogonadism.  Hypogonadism is a condition in which abnormally
decreased functional activity of the gonads results in retardation of growth
and sexual development).  Klinefelter Syndrome is clearly evident only after
puberty with evidence of infertility and/or eunuchoidism of varying degrees.
Abnormally large mammary glands occur with high frequency.

Symptoms

The most common symptoms of Klinefelter Syndrome may include abnormally
small testes which contain sclerosed (hard) tubules, lack of sperm, enlarged
mammary glands, and abnormally small penis.  Mental deficiency may also
occur.  Other clinical manifestations may include retarded development of
external and accessory sex organs, absence of beard and body hair, a high
pitched voice, and a striking lack of muscular development.

If mosaicism (cells consisting of male tissue in one part and female
tissue in another part) with the XXY genotype occurs in only a few cell
lines, many of these characteristics may be absent.  In this case, the only
manifestation of the disorder might be either infertility or decreased
fertility.

Causes

Klinefelter Syndrome results from the presence of supernumerary X
chromosomes.

Affected Population

Only males are predominantly affected with Klinefelter Syndrome.  The rate

of occurrence is 1 in 500.

Therapies:  Standard

Treatment of male primary hypogonadism is with androgens to promote
virilization.  Testosterone enanthate or cypionate may provide satisfactory
replacement.  However, patients with Klinefelter Syndrome cannot become
fertile so gonadotropin therapy need not be considered.  Mastectomy may be
necessary for cosmetic purposes in some patients.

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 Klinefelter Syndrome, please contact:

     National Organization for Rare Disorders (NORD)
     P.O. Box 8923
     New Fairfield, CT  06812-1783
     (203) 746-6518

     Klinefelter's Syndrome Association of America
     P.O. Box 93
     Pine River, WI  54965

     Klinefelter Syndrome and Associates
     P.O. Box 119
     Roseville, CA  95661-0119

     Klinefelter's Syndrome Support Group of Canada
     P.O. Box 5000
     Pentanguishene, Ontario, LOK 1PO
     Canada

     NIH/National Institute of Child Health and Human Development
     9000 Rockville Pike
     Bethesda, MD  20892
     (301) 496-5133

For genetic information and genetic counseling referrals, please contact:

     March of Dimes Birth Defects Foundation
     1275 Mamaroneck Avenue
     White Plains, NY  10605
     (914) 428-7100

     Alliance of Genetic Support Groups
     35 Wisconsin Circle, Suite 440
     Chevy Chase, MD  20815
     (800) 336-GENE
     (301) 652-5553

References

CECIL TEXTBOOK OF MEDICINE, 18th ed.:  James B. Wyngaarden, and Lloyd H.
Smith, Jr., Eds.:  W. B. Saunders Co., 1988.  Pp. 167-70, 1412-13.

THE MERCK MANUAL 15th ed:  R. Berkow, et al:  eds; Merck, Sharp & Dohme
Research Laboratories, 1987.  Pp. 2074-5, 2150.