American Association for Klinefelter Syndrome Information and Support (AAKSIS) is dedicated to bringing you accurate and current information about Klinefelter Syndrome and is a network for individuals, families, and anyone interesting in learning more about Klinefelter Syndrome. Klinefelter Syndrome, 47XXY, the most common of the sex chromosome variations, is said to occur in 1 out of 500 males. Statistics suggest that there are thousands of 47XXY individuals in the United States alone. Many remain undiagnosed.
Kleinfelter Syndrome from the Mayo Clinic. Klinefelter syndrome is a genetic condition that results when a boy is born with an extra copy of the X chromosome. Klinefelter syndrome is a common genetic condition affecting males.