Klinefelter syndrome is the presence of an extra X chromosome in
a male. 47 X-X-Y syndrome Causes, incidence, and risk factors
Most people have 46 chromosomes. Chromosomes contain all of your
genes and DNA, the building blocks of the body. Two sex
chromosomes determine if you become a boy or a girl. Girls
normally have two XX chromosomes. Boys normally have an X and a
Y chromosome. Klinefelter syndrome is when a boy is born with at
least one extra X chromosome. Usually, this occurs due to one
extra X. This would be written as XXY. Klinefelter syndrome
occurs in about 1 out of 500 - 1,000 baby boys. Women who get
pregnant after age 35 are slightly more likely to have a boy
with this syndrome than younger women. - Abnormal body
proportions (long legs, short trunk, shoulder equal to hip size)
- Abnormally large breasts (gynecomastia - Sexual problems -
Less than normal amount of pubic, armpit, and facial hair -
Small, firm testicles - Tall height Signs and tests Klinefelter
syndrome may first be diagnosed when a