Klinefelter syndrome is a chromosomal condition that affects male physical and cognitive development, occurring in approximately 1 in 500 males who are born with an extra X chromosome, giving them a 47,XXY chromosome pattern rather than the typical 46,XY pattern. Males with Klinefelter syndrome may experience delayed or incomplete puberty, infertility, and other physical traits that become apparent during adolescence due to a shortage of testosterone. While not inheritable, it can be treated through hormone replacement therapy such as testosterone injections to help promote typical physical development.

1. Morella Morales
Klinefelter syndrome
http://ghr.nlm.nih.gov/condition/klinefelter-syndrome
http://www.medicinenet.com/klinefelter_syndrome/article.htm
http://learn.genetics.utah.edu/content/disorders/whataregd/klinefelter/
Chromosomal condition that affects male physical and cognitive
development.
When males have an extra X chromosome, when regular people have XY
chromosomes.
People with this disorder develop as males with subtle characteristics that
become apparent during puberty.
One of the most common abnormalities in humans.
About one of 500 males has an extra chromosome.
A shortage of testosterone can lead to a delay in puberty.
Infertile male.
Not inheritable.
Occurs when random events in the formation of the baby occur in the parent.
Males with klinefelter syndrome usually will discover they have the
syndrome when they are delayed on puberty or can’t have children.
Klinefelter can be treated.
The best way to treat this is by hormone replacement.
Teenagers are typically given testosterone injections to replace the hormone
that would normally be produced by the testes
Synthetic testosterone works like natural testosterone - it builds muscle and
increases hair growth.
The disorder is named for Dr. Harry Klinefelter, who first reported its
symptoms in 1942.