What is XYY?
XYY refers to the genetic disorder in males called “XYY syndrome”. In normal males, they are born with one X chromosome and one Y chromosome. But in this genetic condition, male babies are born with an additional Y chromosome, hence the term “XYY syndrome” or medically known as “47 XYY karyotype”. The number 47 represents 47 total chromosomes instead of the normal 46. The extra Y chromosome is the 47th chromosome.
But even with the additional chromosome, males who have this genetic disorder usually do not present any symptoms. This condition also rarely occurs and if it does, it only comes out once in every 1000 male births. And since most boys having this condition are asymptomatic, many of them do not even know that they have the condition. The only chance they have of knowing that they have the XYY syndrome is when they undergo genetic testing. Most boys with this syndrome also develop just like other boys for both sexual and physical characteristics. Testosterone levels are also noted as normal as well as their fertility rates.
Based on studies, males with the XYY syndrome may grow physically taller especially during the early parts of their childhood. They are also said to be more prone to have learning difficulties, particularly in the areas of language and speech. These two characteristics are pretty much what experts believe are the only major difference between normal males and those with the XYY syndrome. Many discredit the notion that XYY males are “super males” and that they tend to be overly aggressive. But this past stereotype has been erased with no clinical evidence to support it. Some experts do acknowledge thought that XYY males are more predisposed to having behavioural problems later in life. But these same people also point out that simple predisposition to a particular condition does not merit any stereotyping of this genetic disorder.