genetic disorder that affects males. Klinefelter syndrome occurs
when a boy is born with one or more extra X chromosomes. Most
males have one Y and one X chromosome. Having extra X
chromosomes can cause a male to have some physical traits
unusual for males. Many men with an extra X chromosome are not
aware that they have it, and they lead normal lives. Males who
have Klinefelter syndrome may be described as XXY males or males
with XXY syndrome. Klinefelter syndrome occurs in about 1 out of
1,000 males. The presence of an extra X chromosome in males most
often occurs when the genetic material in the eggs splits
unevenly. But it can also occur when the genetic material in the
sperm splits unevenly. Many men who have Klinefelter syndrome do
not have obvious symptoms. Others have sparse body hair,
enlarged breasts, and wide hips. In almost all men the testicles
remain small. In some men the penis does not reach adult size.
Their voices may not be as deep. They usually cannot father
children. But they can have a n