Klinefelter Syndrome (KS) is a birth defect in which males are born with at least one extra sex chromosome. In 1942, certain physical characteristics, abnormal in adult males, were first identified by Dr. Harry Finch Klinefelter, Jr. and two colleagues. These characteristics were abnormally small testes and fatty breast tissue. Detailed chromosome studies conducted years later resulted in the discovery that males with these characteristics have an extra sex chromosome
American Association for Klinefelter Syndrome Information and Support – AAKSIS (pronounced “access”)
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.
2945 W. Farwell Ave.
Chicago, IL 60645-2925
Phone: 888 466-5747
Fact Sheet last updated on: 4/10/2020