Klinefelter syndrome

47 XXY syndrome; XXY syndrome; XXY trisomy; 47,XXY/46,XY; 47,XXY/46,XY mosaicism; Poly-X Klinefelter syndrome

Klinefelter syndrome, also called 47,XXY, is a genetic condition that occurs in males when they have an extra X chromosome. This can cause problems with development and fertility. Some men have no symptoms and never know they have it.


Karyotyping is a test used to identify chromosome abnormalities as the cause of malformation or disease. The test can be performed on a sample of blood, bone marrow, amniotic fluid, or placental tissue.



Exams and Tests


Support Groups

Possible Complications

When to Contact a Medical Professional