Download Klinefelter’s syndrome is caused by a nondisjunction event

Klinefelter’s Syndrome
By Greg Schreck
and
Troy Krause
Klinefelter’s syndrome is caused by
a nondisjunction event during
meiosis 1. A gamete ends up with
two sex chromosomes, and when
the two sex chromosomes of one
parent are added to the one of the
other it causes a trisomy in their
offspring. Because it is caused by
nondisjunction, the disorder is
neither dominant or recessive.
Klinefelter’s Syndrome is the
result of nondisjunction, so the
parents may have perfectly
normal genotypes. The
abnormality that occurs is that a
male inherits an extra X
chromosome for an XXY
genotype (not XY.)
1 in 1000 men have the
syndrome, and 1 in 500 males
have the trisomy but do not
express symptoms. Women
cannot inherit this condition.
Because the disease affects the
testes, most people who have it
find that they are sterile, and so
they cannot pass it onto their
offspring.
A karyotype is all that’s needed to
diagnose individuals with
Klinefelter’s syndrome as an extra
sex chromosome is rather easy to
spot. The disorder can be
diagnosed prenatally as well using
chorionic villus sampling
or amniocentesis.
Most men have no idea that they’re
affected with this disease until they
hit puberty. Symptoms include:
-More breast tissue than normal
-A less muscular body
-Little to no facial or body hair
-Sterility (can’t have children)
-Learning disabilities (not classified
as mental retardation) are also
common.
The Life expectancy of an
individual with klinefelter’s
syndrome is 5 years less than
average.
Injections of testosterone are
used as treatment to replace the
testosterone that would
normally be produced by the
body. The synthetic testosterone
has the same function as
testosterone naturally found in
the human body; it increases
muscle mass and hair growth.
No one’s really pursuing cures
or treatments of klinefelter’s. the
disorder is easily managed with
horomone therapies and there’s
seemingly no possible cure
because the extra chromasome
cant just be removed from all
the cells of the afflicted.
Sources:
www.wikipedia.com
www.nlm.nih.gov
www.webmd.com
http://www.nlm.nih.gov/medlineplus/