The Klinefelter Syndrome

Nadia Tokovic

Mr. Youell

Science 9 Extended

13 October 2014

The XXY (Klinefelter) syndrome

An article on NY Times talks about a boy named Sam who was diagnosed with the Klinefelter syndrome. Sam’s parents began to suspect that something wasn’t right, when he hasn’t started to walk or speak at the age of 2. His parents decided to test him to see if he had any medical condition, and only the genetic test showed an abnormality. Sam’s cells had an extra copy of the X chromosome, instead of the normal combination for a boy: just XY (see fig. 1). The Klinefelter syndrome is actually, one of the most common genetic abnormalities, it occurs in around 500-1000 newborn males, however about two thirds of boys and men that have this syndrome do not even notice it. At 13 years old, Sam receives special education services, and is able to keep up at school. His speech is completely normal, and he loves to participate in sports and athletics, despite some of his social problems. His levels of testosterone are checked by a doctor, and as he enters puberty, if they drop below normal, he will be receiving testosterone treatments.

Fig 1. Karyotype of a male with Kleinfelter Syndrome

The “XXY syndrome” is also known as the Klinefelter syndrome. It was discovered in 1942 by Dr. Harry Klienfelter, hence the name. This is a chromosomal syndrome that affects male physical and mental development. It is caused by an extra X sex chromosome in each cell, which is caused by a mistake in cell division (non-disjunction). This genetic abnormality cannot be inherited, because chromosomal changes occur completely randomly during the process of meiosis (the formation of sex cells).

 The effects of this syndrome can vary between individuals. Common effects of this condition are: 

•        Taller than peers
•        Shortage of testosterone
•       Reduced facial and body hair
•      Delayed or incomplete puberty
•      Breast development
•      Infertility
•      Small testes
•      Small penis
•      Delayed speech development (difficulty learning to read and write)
•      IQ ability slightly lower than average
•      Sudden mood swings, depression, social problems (no psychiatric disturbances)
•      Have an increased risk of developing breast cancer and chronic inflammatory disease called systemic lupus erythematosus

Once a Klinefelter syndrome is diagnosed, regular testosterone treatments can stop many of the symptoms and consequences listed above. Early recognition of this abnormality can greatly improve the quality of the person’s life. The testosterone treatment can improve mood and behavior, increase masculinity, strength, bone mineral density and body hair. However, it cannot cure infertility. Boys that are diagnosed at a school age can greatly be helped by special educational services to keep up at school and be helped with any behavioral problems they might have.

According to The Genetic Home Reference, there are many different variants of the Klinefelter syndrome:  some people have more than 1 extra X chromosome in their cells, such as “XXXY”, who usually show more severe symptoms than the original Klinefelter Syndrome. However, there are also males who have an extra X chromosome in only some of their cells, and they tend to show milder symptoms.

In conclusion, this syndrome is a quite common one, but its effects are not as extreme as other genetic syndromes can be. With proper treatment, boys and men, with this syndrome, such as Sam can live an almost completely normal life.