Klinefelter syndrome (KS) occurs in some men who have more than
one X chromosome (XXY). Copyright © Nucleus Medical Media, Inc.
Males usually inherit a single X chromosome from their mother
and a single Y chromosome from their father. Males with KS get
at least one extra X chromosome. A risk factor is something that
increases your chance of KS. Women over age 35 have a slightly
increased chance of having a child with KS. There are no other
known risk factors for this disorder. XXY occurs in
approximately 1 out of 580 live male births, but many men with
it do not develop KS. When KS does develop, it usually goes
undetected until puberty or sometimes much later.
Characteristics may include: Men with KS have an increased risk
of: A test called a karyotype is used to diagnose KS. In the
case of KS, there are usually 47 chromosomes rather than the
normal 46. Many men with XXY do not know they have the
condition. The diagnosis may be found: Treatment of KS includes:
The main treatment is testosterone. When boys wit