Other Interesting Facts

• No females can be born with XYY Syndrome, only male
• XYY Syndrome males are usually sterile
• XYY Syndrome (47,XYY) is often compared to 47,XXX Syndrome, 45,X, and 47,XXY Syndrome. Perhaps there is some relation. Maybe it's paranormal???

 

• The earliest known case of XYY Syndrome was in the 1960's was Avery Sandburg
• In 1974, a psychologist named John Money experimented with 13 XYY boys by giving them a high dosage of Depo-Provera, resulting in weight gain and suicide

Current Research

In the last decade, multiple tests have been done to get further information on XYY Syndrome, due to the significant increase of XYY males being born. Tests have been done in Boston, Scotland, and many other places, but so far not much information is being found, because there is NOTHING on Google! LITERALLY NOTHING!

The Medical Side of Things

Most males will go their entire life without knowing they have XYY Syndrome. However, chromosome tests can be done through blood samples of skin samples. It can also be prenatally diagnosed through cytogenetic analysis of cells trough procedures like amniocentesis and chorionic villus sampling.Genetic counseling is likely an option to help with people to feel comfortable with themselves and other males with XYY Syndrome. Unfortunately, XYY Syndrome is untreatable and there is no known treatments or cures.

Cause and Incidence

XYY Syndrome is not inherited, but rather is caused by a random formation of sperm cells. An error in chromosome separation during Anaphase II of Meiosis II called nondisjunction can result in the duplication of a Y chromosome.It occurs averaging in every 1 of every 1000 males. 

Behavioral Characteristics

In males with XYY Syndrome, their IQ was not affected whatsoever. Developmental delays and behavioral problems can also occur, as well as significant aggression. Studies also show a significant amount of XYY boys to have learning difficulties. They are at an increased risk for psychiatric disorders and ADD. XYY Syndrome has been proven to have a lot of the same characteristics as autism.

What is XYY Syndrome?

XYY Syndrome is a sex-linked disorder where males receive and extra Y chromosome, giving them 47 chromosomes, whereas a normal human has 46. It occurs in 1 out of every 1000 human males.

An XYY Karyotype. Notice the 2 Y chromosomes on the sex-linked genes

Physical Traits

Males will have an increased growth velocity from early childhood to adulthood. The average final height of a male is 3 inches above the expected height. In Scotland, 8 XYY males were tested in 1967-1972, and their average height was 188.1 cm, or 6'2" at age 18, while their father's average height was 174.1 cm, or 5'8 1/2" and their mother's average height was 162.8 cm, or 5'4". There is also a chance of severe acne. Testosterone levels are also abnormally high in males with XYY Syndrome.