Klinefelter syndrome occurs due to a chromosomal abnormality where a baby boy is born with an extra X chromosome. Chromosomes are a bundle of found in each cell of the body which carry genetic information which determine hereditary traits. There are two types of chromosomes which work to determine whether the genetic sex of the baby is male or female - these are the sex chromosomes. The sex chromosomes consist of either X or Y.
A female baby is born with the chromosome pattern of XX whilst a male baby boy is born with the chromosome pattern of XY. However, in the case of males affected by Klinefelter syndrome, the baby boy is born with the chromosome pattern of XXY (an extra X chromosome in the pattern). This means that an individual with Klinefelter syndrome is still genetically male, but may experience development problems that will require treatment.
It is therefore present from the birth of the little boy, but its symptoms usually only become visible at puberty. These include the presence of small testicles or the abnormal development of the mammary glands. While normally secretion of testosterone increases at puberty, it decreases in patients with Klinefelter syndrome.
In some cases, however, the symptoms are poorly visible and Klinefelter's syndrome is diagnosed only in adulthood when the patient experiences infertility problems. A blood test can then confirm or invalidate the diagnosis. Klinefelter syndrome is quite common since it affects one in 600 males.
The symptoms of Klinefelter syndrome vary from person to person. Some will have very few symptoms. Only infertility is common to all men with the syndrome.
In young adolescents:
- Above average height
- Small testicles
- Growth in mammary glands
- Reduced facial and body hair
- Taurodontism (a condition that affects the teeth and increases the risk of cavities)
- Slower language learning, reading and motor development
- Infertility with almost total absence of sperm
- Early osteoporosis
Klinefelter syndrome occurs directly as a result of the presence of an extra X chromosome. This additional chromosome carries an extra piece of identical genetic information which interferes with usual pubescent development. The cause of complications occurs as a result of underdevelopment of the testes, leading to a decreased production of testosterone.
Instead of having 46 chromosomes as is usually the case after conception, an individual with Klinefelter syndrome has 47. This "genetic accident" occurs most often in late pregnancy and is not directly inherited by the offspring, but rather as a result of the mother's egg or the father's sperm carrying an extra X chromosome (equal likeability for either case).
The anomaly occurs at random. This means that the chances of multiple offspring developing the syndrome are unlikely. The chances of a baby boy developing Klinefelter syndrome may be higher if the mother is over the age of 35 years old.
Since Klinefelter syndrome is of chromosomal origin, there is no treatment that completely cures all its symptoms. Hormonal testosterone therapy that begins at puberty, however, prevents the appearance of most physical symptoms. Administered in the form of injection, tablets or gel, this regular treatment allows the patient to develop hair, muscle and a broken voice as they would during puberty and to strengthen their bones.