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What is Klinefelter Syndrome?

by Josephine Andrews
Published: Last Updated on 425 views

Klinefelter syndrome is a genetic disease. It only affects men. They carry too many sex chromosomes in their cells. Typical symptoms are tall stature and infertility. Klinefelter syndrome cannot be cured. However, there are various medications to alleviate the symptoms. Read all about Klinefelter Syndrome here!

Klinefelter syndrome: description

Klinefelter syndrome is a genetic condition that only affects males. They have at least one so-called sex chromosome too many in their cells. The term XXY syndrome is also common.

Klinefelter syndrome is called a syndrome because there are different symptoms that occur simultaneously and are related to each other. It is also called a symptom complex. The Klinefelter syndrome features were first identified in 1942 by American physician Dr. Harry Klinefelter described.

Klinefelter syndrome: Occurrence

Klinefelter patients are always male. Statistically, approximately one boy in every 500 to 1000 live births is affected by Klinefelter syndrome. Statistical calculations suggest that around 80,000 men in Germany suffer from Klinefelter’s syndrome. With only around 5,000 confirmed cases, a high number of unreported cases is suspected.

Klinefelter syndrome is the most common chromosomal abnormality (chromosomal aberration) in men and the most common genetic reason for male infertility .

Klinefelter syndrome: symptoms

Klinefelter’s syndrome varies greatly from person to person and can affect many different organ systems. The childhood of those affected is usually unremarkable. During this time you may experience symptoms such as:

  • delayed language and motor development
  • Learning difficulties with often normal intelligence
  • tall with long legs

Klinefelter’s syndrome often only becomes apparent during puberty. This usually occurs with a delay or not at all:

  • Beard growth and secondary hair are absent or sparse.
  • The voice break is missing: the patients keep a high voice.
  • The sex drive (libido) is reduced
  • The testicular volume (the size of the testicles) remains small
  • The men are not fertile
  • The body fat distribution is more female

There can also be other problems:

  • anemia
  • osteoporosis (bone loss)
  • muscle weakness
  • Diabetes mellitus (diabetes)
  • Tendency to thrombosis (occlusion of vessels)
  • tiredness , listlessness
  • Gynecomastia (enlargement of the mammary glands)

Klinefelter syndrome: causes and risk factors

In order to better understand Klinefelter syndrome, here are some definitions of terms. Klinefelter syndrome is based on a chromosomal aberration. Doctors understand this to mean that the number or structure of the chromosomes is disturbed.

Our genetic information is stored on the chromosomes. Normally there are 46 chromosomes in each cell. This includes two sex chromosomes. In the female karyotype (set of chromosomes) they are designated as XX, in males as XY. A normal karyotype is accordingly described as 46, XX or 46, XY.

Klinefelter syndrome has more than 46 chromosomes.

Klinefelter syndrome: different karyotypes

Various karyotypes can lead to Klinefelter syndrome:

  • 47, XXY: Approximately 80 percent of patients have an additional X chromosome in all body cells.
  • 46, XY/47, XXY: Some patients have cells with a normal and an altered set of chromosomes in their bodies. This is called a mosaic.
  • 48,XXXY; 48, XXYY; 49, XXXXY: There are special cases in which there is not just one extra X chromosome in the cells, but several. Additional Y chromosomes are also possible.

How does Klinefelter syndrome develop?

The cause of Klinefelter syndrome lies in the maturation of the father’s sperm cells or the maturation of the mother’s egg cells.

In what is known as meiosis, the pairs of chromosomes (XX in the egg cell, XY in the sperm cell) are separated. If this does not happen, a complete pair of chromosomes is passed on and Klinefelter syndrome develops.

The double X chromosome interferes with the formation of testosterone in the testicles . Since the male sex hormone testosterone is not only important for the development of the sex organs and characteristics, but also takes on various tasks in the human metabolism, the Klinefelter syndrome symptoms are so diverse.

In addition, the remaining X chromosome is partially suppressed. This mechanism is developed differently from patient to patient and ensures a different severity of symptoms.

Klinefelter Syndrome: Investigations and Diagnosis

Due to the mild symptoms in childhood, Klinefelter’s syndrome is often only diagnosed during puberty and sometimes even in adulthood when unwanted childlessness occurs.

At the time of compulsory military service, affected men were conspicuous in the so-called screening due to a small testicle volume. Nowadays, the Klinefelter syndrome is mainly diagnosed during the preventive examination of young people at the pediatrician, the J1.

Depending on the age, treatment is carried out by a pediatrician, endocrinologist or andrologist – sometimes by several disciplines together.

Klinefelter syndrome: diagnostics

In order to make the diagnosis of Klinefelter syndrome, the doctor first asks the patient in detail about his or her medical history ( anamnesis ). Here are some of the questions he will likely ask you:

  • Did you have trouble keeping up at school?
  • Do you often feel sluggish?
  • When did your puberty start?
  • Have you and your partner been trying to have a child for a long time without success?

Klinefelter Syndrome: Physical Examination

The doctor then examines the patient physically. First of all, he pays attention to the external appearance, in particular the body proportions. Is the patient tall? Does he have longer than average legs? In addition, the doctor examines the body hair and the mammary gland.

The size of the testicles is also measured. It is usually significantly reduced in Klinefelter patients.

Klinefelter syndrome: blood test

After taking a blood sample, various hormone levels can be determined in the laboratory. Patients with Klinefelter syndrome usually have low levels of testosterone and high levels of FSH and LH in the blood . Doctors then speak of hypergonadotropic hypogonadism , i.e. underdevelopment of the gonads despite high hormonal stimulation.

In addition, the blood cells taken can be viewed under a microscope and the number and structure of the chromosomes can be analyzed. The XXY syndrome can be easily recognized because there are (at least) three sex chromosomes instead of two

Klinefelter Syndrome: Prenatal Studies

The so-called prenatal diagnosis offers the possibility of diagnosing a Klinefelter syndrome before birth. Such an early diagnosis offers the chance to provide the child with the best possible care and targeted support right from birth.

Prenatal diagnostics include invasive examinations such as amniocentesis : the doctor takes a small sample of the amniotic fluid from the pregnant woman. It contains child cells whose genetic material (DNA) can be analyzed for a wide variety of chromosomal changes (anomalies) such as Klinefelter syndrome. The disadvantage of invasive prenatal tests like amniocentesis is that they can cause miscarriage .

Non-invasive prenatal blood tests (NIPT) such as the Harmony test, Praena test and Panorama test do not have this disadvantage . You only need a maternal blood sample: it contains traces of the child’s genetic material that can be checked for chromosomal abnormalities. The prenatal blood tests deliver quite reliable results, but cost several hundred euros (depending on the test and the scope of the analysis).

If a Klinefelter syndrome is actually detected in the unborn child by means of prenatal diagnostics, this is no reason for an abortion! The symptoms of those affected are usually mild and not life-threatening.

Klinefelter syndrome: treatment

Klinefelter syndrome cannot be cured because it is caused by a chromosomal aberration. This cannot be influenced.

It is therefore necessary to treat the Klinefelter syndrome symptoms. The most important starting point is the low testosterone level in the blood of those affected. Therefore, patients receive artificial testosterone for life. This is also known as testosterone substitution. Gels, patches and syringes are available for this. Tablets are not used because the hormone breaks down quickly in the gastrointestinal tract and can lead to intolerance.

Whether a gel, patch or injection is used also depends on the patient’s preferences. Gels have the advantage of not being painful. However, they must be applied daily. Patches should be changed every two days. Injections come in the form of depot injections that only need to be administered every four weeks to three months.

Before testosterone substitution takes place, a malignant tumor of the prostate gland (prostate carcinoma) must be ruled out. Testosterone makes such tumors grow faster, so they must be treated first.

Klinefelter syndrome: therapy control

The effectiveness of the testosterone treatment should be checked regularly by taking a blood sample. The values ​​for testosterone and other hormones such as LH, FSH and estradiol are monitored for this.

The red blood cells ( erythrocytes ) are also examined because their formation is promoted by testosterone. In addition, bone density should be measured every two to three years in order to detect possible osteoporosis at an early stage. In addition, the breast should be scanned regularly, since Klinefelter patients have a higher risk of breast cancer.

Successful testosterone therapy is reflected in increased performance and reduced fatigue as well as prevention of osteoporosis, diabetes mellitus and muscle weakness.

Klinefelter syndrome: disease course and prognosis

Klinefelter syndrome usually has mild symptoms. Through consistent testosterone therapy and targeted support at school, the patients lead a balanced and self-determined life.

Nevertheless, infertility is a particular burden for those affected. The Klinefelter syndrome life expectancy is limited in that patients are 20 times more likely to develop breast cancer.

Patients with Klinefelter syndrome have average intelligence. However, they often need more time to learn new things. Speech and motor development should be promoted early on with speech therapy and occupational therapy .

Klinefelter syndrome: desire to have children

To give Klinefelter syndrome patients the opportunity to father children, sperm cells can be removed from the testicles in early adolescence.

At the time and before testosterone therapy, the chance of finding functioning sperm is highest. The material obtained from the testicular biopsy is analysed, processed and frozen ( cryopreservation ). In this way, it is preserved for a long time and is available if you want to have children later. An egg cell is then removed from the woman and artificially fertilized with sperm cells.

Parents of a child with Klinefelter syndrome have no increased risk that another child will also develop the disease.

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