Klinefelter syndrome, also known as XXY syndrome, is a genetic disorder that involves an additional X sex chromosome in males. Physiologically, males inherit one X chromosome from their mothers and one Y chromosome from their fathers and thus possess XY. Males with Klinefelter syndrome have an additional X chromosome that is inherited from either the mother or the father and therefore have XXY.
Unlike many genetic problems, Klinefelter syndrome is not a hereditary condition that is inherited from the parents. Instead, it is thought to occur as a result of a random error in the meiosis of the sperm or egg cell.
A risk factor for the condition is a mother who is older at the time of conceiving. The age of the father may also be an associated factor.
Klinefelter syndrome is estimated to affect approximately 1 in 500 male babies and is, therefore, one of the most common chromosomal variations. However, only about 25% of these cases are diagnosed with Klinefelter syndrome and the majority do not have an impact on sexual characteristics. The prevalence of the condition is considerably higher (5-20 times) in individuals with mental retardation than in the general newborn population.
Throughout the early stages of life, the symptoms of Klinefelter syndrome are usually very subtle. A young boy may have undescended testicles, weak muscles and delayed motor skill and speech development.
At the age of puberty, however, signs of the condition become more obvious as there are insufficient testosterone levels required to complete the normal development. Men may have a small penis and testicles, enlarged breast tissue, low bone density, fatigue, quiet character and tall stature with long legs, short torso and broad hips.
However, many men won’t report these symptoms and diagnosis of the condition is only made when the man wishes to start a family and struggles with the problem of infertility.
Males with Klinefelter syndrome have a heightened risk of several health conditions, such as:
- Diabetes mellitus
- Lung diseases
- Depression and anxiety
An individual usually presents with symptoms of Klinefelter syndrome during childhood, puberty or adulthood when infertility becomes an issue. The initial stage of the diagnostic process is a physical examination to investigate for signs of the condition, such as a small penis and testicles or enlarged breast tissue.
To confirm the diagnosis, chromosomal analysis with a karyotype testing is required. This involves a blood or skin sample, which is examined for the additional X chromosome that is characteristic of Klinefelter syndrome.
There is no cure for Klinefelter syndrome and the treatment of the condition focuses on improving symptoms and providing support to the individual.
Hormonal androgen therapy can help to increase testosterone levels and induce the normal changes at the age of puberty. This is a life-long treatment that can help to reduce symptoms of the condition by improving energy levels and physical strength.
For infertile men who wish to have a child, in vitro fertilization (IVF) may be an option. As a result of new reproductive technologies, up to 25% of men with Klinefelter syndrome are now able to have biological children, which was previously very rare.
Other treatments that may be required include speech, physical, occupational and cosmetic therapy as well as counseling.
Reviewed by Jonas Wilson, Ing. Med.