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The Association For X and Y Chromosome Variations


P.O. Box 861
Mendenhall, PA 19357 USA

800 Number


Email Address


The Association For X and Y Chromosome Variations, is a voluntary, non-profit organization whose mission is to help individuals with one or more extra X and/or Y chromosomes and their families lead fuller and more productive lives. Klinefelter syndrome is characterized by the presence of an extra X chromosome in males. The most common symptoms of Klinefelter syndrome may include abnormally small testes and impaired function of the testes resulting in infertility. Some males with this disorder may have abnormally enlarged breasts (gynecomastia). The development of secondary sexual characteristics may be diminished resulting in a high-pitched voice and the lack of facial and body hair. Major muscles of the arms and legs may remain underdeveloped. Many other variants of Klinefelter syndrome can occur, including chromosome abnormalities such as 46,XY/47,XXY (mosaic), 48,XXXY, and 48,XXYY. KS&A also provides support to individuals with other sex chromosome abnormalities including females wtih triple X syndrome.

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