Xyy Syndrome

XYY Syndrome is a rare genetic disorder which affects males due to an extra Y chromosome. Healthy males have 46 chromosomes including one X and one Y chromosome. Men with XYY syndrome have 47 chromosomes, two of which are Y chromosomes. It is not known why the extra Y chromosome occurs. The disorder is present at birth and is estimated to occur in one out of every one thousand live births.

In very rare instances, the syndrome has been passed from father to son, but

in most cases heredity cannot be established.

The characteristics of XYY syndrome are often very subtle and do not indicate and serious chromosomal disorder. Therefore, males with this condition are frequently undiagnosed or misdiagnosed. The primary symptoms include tall or very tall height which becomes evident at the age of five or six, and severe cystic acne during adolescence.

Lower than average intelligence and/or behavioral problems, such as an explosive

temper, aggressive or defiant actions, or sometimes antisocial behavior are

other symptoms. Some individuals with this disorder may also have language

difficulties or psychosexual problems. XYY Syndrome is often undiagnosed until

tests for other medical reasons are performed. Other than being unusually

tall and/or having behavioral problems, in many cases, these boys or men appear

normal.

Physical characteristics of XYY Syndrome may include an exceptionally

long head with a slightly protrusive forehead, long hands and feet, long ears,

mild indentation of the breastbone, and/or large teeth. Poor chest and shoulder

muscle development is also common. Even though males with this syndrome are

large, they tend to be weak and uncoordinated. Some may have a fine intentional

tremor, such as shaking hands when the try to drink a glass of water. Occasionally,

a bony formation across the joints in the two bones of the forearm resulting