Down syndrom

and Martina Feichter, medical editor and biologist

Martina Feichter studied biology with an elective subject pharmacy in Innsbruck and also immersed herself in the world of medicinal plants. From there it was not far to other medical topics that still captivate her to this day. She trained as a journalist at the Axel Springer Academy in Hamburg and has been working for since 2007 - first as an editor and since 2012 as a freelance writer.

More about the experts All content is checked by medical journalists.

Down syndrome, also known as trisomy 21, is a chromosomal disorder. Affected people have three copies of chromosome number 21 - usually each person has only two. The excess genetic material affects physical and mental development. How serious the effects are varies from person to person. Read everything you need to know about Down syndrome here!

ICD codes for this disease: ICD codes are internationally recognized codes for medical diagnoses. They can be found, for example, in doctor's letters or on certificates of incapacity for work. Q90

Brief overview

What is Down Syndrome? Not a disease, but a genetic anomaly. This means that the genetic makeup of those affected deviates from the "normal state".
Causes: Three (instead of two) copies of chromosome 21 can be found in all or some of the body cells of those affected. This is why Down's syndrome is also called trisomy 21.
Frequency: most common deviation from the normal number of chromosomes (numerical chromosome abnormality). It is estimated that one in 650 babies is born with Down syndrome. Around 30,000 to 50,000 people are affected in Germany.
Typical symptoms: including short head, flat back of the head, round and flat face, slanted eyes with a delicate crease in the inner corner of the eye, mostly open mouth with increased salivation, four-finger furrow, gap in sandals, short stature
Possible consequences: heart defects, malformations in the digestive tract, orthopedic problems (such as flat feet), hearing and vision disorders, increased susceptibility to infections, sleep-related breathing disorders, increased risk of leukemia, epilepsy, autoimmune diseases, autism, ADHD, etc., but also intellectual disabilities special skills such as musical talent
Treatment: targeted individual support (as early as possible), for example by means of physiotherapy, occupational therapy and speech therapy; surgical treatment of organ and skeletal malformations; Treatment of comorbidities

Down syndrome: symptoms and consequences

People with Down syndrome (trisomy 21) can usually be recognized by their typical appearance. Characteristic Down syndrome symptoms are:

short head (brachycephaly) with a flat back of the head, a short neck and a round, flat face
slightly slanted eyes with delicate skin folds at the inner corner of the eye (epicanthus)
increased interpupillary distance
bright, white spots on the iris ("brushfield spots") - they disappear with age and with the accumulation of color pigments in the iris
flat, broad bridge of the nose
mostly open mouth and increased salivation
lined tongue that is often too large and protruding from the mouth (macroglossia)
narrow, high palate
underdeveloped jaws and teeth
small, deep-set, rounded ears
excess skin on the nape of the neck, short neck
short broad hands with short fingers
Four-finger furrow (transverse furrow on the palm of the hand, starting under the index finger and continuing to below the little finger)
Sandal gap (large space between first and second toe)

Slanted eyes and a flat nasal bridge are not only found in people with Down syndrome, but also in the Mongolian tribe. This is why Down's syndrome used to be popularly known as "Mongolism" and those affected as "Mongoloid". For ethical reasons, however, these terms should no longer be used.

Other Down syndrome features include poorly developed muscles (low muscle tension) and delayed reflexes. The body growth of those affected is slower and they are below average (short stature). In addition, a pronounced weakness of the connective tissue makes the joints excessively mobile.

Down syndrome: health consequences

Trisomy 21 can affect health. Heart defects are particularly common features of trisomy 21. They occur in around half of all people with Down syndrome. A common heart defect is the so-called AV canal (atrioventricular canal). This is a septum defect between the atria and ventricles. It causes shortness of breath, growth disorders and recurring pneumonia. In many cases the heart septum between the heart chambers is not completely closed either (ventricle septum defect).

Down syndrome is also very often associated with malformations in the gastrointestinal tract, for example narrowing in the area of the small intestine or malformations of the rectum. Hearing and vision disorders are also common.

Because the immune system is underdeveloped, people are more susceptible to infections, especially in the respiratory tract. Many Down syndrome children are prone to otitis media, bronchitis and pneumonia.

In many cases, trisomy 21 is associated with a sleep-related breathing disorder (obstructive sleep apnea), sometimes accompanied by snoring: the upper airways relax and narrow during sleep, which leads to brief pauses in breathing. The oxygen saturation in the blood drops each time. The brain reacts to this with a wake-up impulse. However, those affected quickly fall asleep again and usually cannot remember the short periods of wakefulness the next day. However, they are often tired during the day because there is a lack of restful, consistent sleep.

Another consequence of trisomy 21 is the increased risk of acute leukemia (a type of blood cancer): it is up to 20 times more than in children without this chromosomal abnormality. There are several genes on chromosome 21 that play an important role in the development of leukemia. The so-called acute myeloid leukemia (AML) is more common in Down syndrome than acute lymphoblastic leukemia (ALL) - in children without trisomy 21 it is exactly the opposite.

In addition to leukemia, epileptic seizures (epilepsy) and autoimmune diseases are more common in Down syndrome than in the normal population. The latter include, for example:

Type 1 diabetes mellitus
Celiac disease
Chronic rheumatic disease in childhood (juvenile rheumatoid arthritis, also called juvenile idiopathic arthritis)
autoimmune thyroid disorders (such as Hashimoto's thyroiditis).

In addition, orthopedic problems are often observed with trisomy 21. These include, for example, malpositions in the neck and shoulder area as well as in the hip (hip dysplasia), an unstable kneecap and malformations in the feet (such as flat feet).

In addition, people with Down syndrome have an increased risk of behavioral problems or psychiatric illnesses, for example ADHD, autism, anxiety disorders and emotional problems up to depression.

Down syndrome also affects fertility: boys or men with trisomy 21 are usually sterile (infertile). Affected girls and women, on the other hand, are fertile (albeit to a limited extent). The probability that they will pass on the chromosomal abnormality to the unborn child during pregnancy is around 50 percent.

Down Syndrome: Mental Limitations

Down syndrome is the leading cause of congenital intellectual disability. Trisomy 21 children often learn to speak later than other children, partly because they tend to hear less well. This is also why their language is sometimes difficult to understand. In many cases, it takes people longer to understand the issue. It is often difficult for them to remember what they have already learned when they have to learn new things. Motor development is delayed - the children start crawling or walking late.

The intellectual abilities are more or less limited. Some people are severely mentally impaired (but this is relatively rare), while others have almost average intelligence. The following applies: The intellectual development of a Down syndrome child depends not only on their genetic makeup, but also on whether and to what extent they are encouraged.

Down Syndrome: Special Skills

Trisomy 21 doesn't just mean malformations and limitations. People with Down syndrome have strong emotional abilities and a sunny disposition: They are loving, affectionate, friendly and cheerful. In addition, many are musically gifted and have a strong sense of rhythm.

Down syndrome: causes and risk factors

Down syndrome is due to an error in the production of germ cells (egg cells or sperm):

Egg and sperm cells arise from cell division from precursor cells with a normal double set of chromosomes (chromosomes = carriers of the genetic make-up). This double set of chromosomes includes 22 paired autosomes plus two sex chromosomes (XX in women and XY in men). So that's a total of 46 chromosomes.

During the process of division, the genetic information is normally distributed evenly to the germ cells that develop, each of which then has a simple set of chromosomes (22 autosomes and one sex chromosome = 23 chromosomes). In the event of later fertilization, the fusion of the egg cell and sperm can result in a cell with a normal double set of chromosomes, from which the child then emerges through countless cell divisions.

Errors can occur when dividing the 46 chromosomes into the germ cells that are created: Sometimes the two copies of a chromosome accidentally end up in one and the same new germ cell. This then has a total of 24 instead of 23 chromosomes. If it later fuses with another "normal" germ cell during fertilization, the result is a so-called trisome cell - it contains three copies of the chromosome in question - a total of 47 chromosomes. In Down syndrome, chromosome number 21 is present in three (instead of two) versions. Doctors differentiate between different forms of Down syndrome: Free trisomy 21, mosaic trisomy 21 and translocation trisomy 21.

Free trisomy 21

All cells in the body are equipped with a third chromosome 21. It is almost always a spontaneous new mutation. This means that free trisomy 21 usually arises by chance, i.e. for no apparent reason. About 95 percent of all people with Down syndrome have a free trisomy. This is by far the most common variant of the chromosomal disorder.

This is how the free trisomy 21 arises

If the duplicate chromosomes 21 are wrongly not separated during egg cell formation, an egg cell will contain three instead of two chromosomes 21 after fertilization - two from the egg cell and one from the sperm.

Mosaic Trisomy 21

Sometimes the surplus third chromosome 21 is lost again during cell division during embryonic development in one cell ("trisomy rescue"), but not in others. This means that "normal" and trisome cell lines develop as a result. The child's body consists of cells with 46 and 47 chromosomes.

The same result arises if fertilization takes place normally (the fertilized egg cell has 46 chromosomes), but an error occurs in the subsequent embryonic development: When a single cell divides, three chromosomes 21 can accidentally be in a daughter cell (and only one copy in the second daughter cell). Here, too, both "normal" and trisome cell lines develop as a result.

Mosaic trisomy occurs in approximately two percent of all people with Down syndrome. Depending on whether the person concerned has more "normal" or more trisome cells, the characteristics of Down syndrome are differently pronounced.

Translocation trisomy 21

This form of Down syndrome usually has its origin in a parent with a so-called "balanced" translocation 21. That means: The affected parent normally has two copies of chromosome 21 in his body cells. However, one of them is attached to another chromosome (translocation). This has no consequences for the parent himself. When conceiving a child, however, an "unbalanced" translocation 21 can arise: The child then has three copies of chromosome 21 in all body cells, one of which is attached to another chromosome.

A translocation trisomy 21, which is based on a balanced translocation of one parent, can occur more frequently in a family. This means that several children of the affected parent can have Down syndrome (in the form of translocation trisomy 21).

Only rarely does a translocation trisomy 21 arise spontaneously either shortly before or after fertilization of the egg cell.

Translocation trisomy 21 accounts for about three percent of all cases of Down syndrome.

Down syndrome: risk factors

In principle, with every pregnancy there is the possibility that the child will be born with Down syndrome (or another genetic disorder). However, as the mother ages, the likelihood of this increases. In women aged 35 to 40, 1 in 260 children is born with trisomy 21. For 40 to 45-year-old pregnant women, the ratio is already 1 to 50.

Scientists suggest that egg division is more prone to disturbances as the woman ages. This could make it easier to make mistakes in the division of the chromosomes. Whether the father's age also plays a role is controversial.

Researchers are also discussing other factors that may contribute to Down syndrome. These include, on the one hand, endogenous (internal) factors such as certain gene variants. On the other hand, exogenous (external) influences are also suspected, for example harmful radiation, alcohol abuse, excessive smoking, use of oral contraceptives or a viral infection at the time of fertilization. However, the importance of such factors is controversial.

Down syndrome: examinations and diagnosis

As part of prenatal diagnostics, it can be determined before birth whether a child has Down's syndrome (or another chromosomal disorder or genetic disease). Several examination methods are possible:

The so-called non-invasive procedures such as the first trimester screening (ultrasound and blood test) and the triple test (blood test) are risk-free for mother and child. In particular, the first trimester screening (at the end of the first trimester of pregnancy) provides good evidence of trisomy 21 in the unborn child, but does not allow a reliable diagnosis. The result of the screening only provides an assessment of how high the risk of "Down syndrome" is in the unborn child.

In order to be able to diagnose Down syndrome with certainty, a direct analysis of the child's chromosomes is necessary. The sample material is obtained via a tissue sample from the placenta (chorionic villus sampling), an amniocentesis (amniocentesis) or a fetal blood sample (umbilical cord puncture). All three procedures are interventions on the womb (invasive methods). They are associated with some risk to the child. That is why they are only used in specific suspected cases, for example if the ultrasound findings are unclear. Even with pregnant women The risk of a miscarriage as a result of the procedure and the risk of Down syndrome from the age of 35 cancel each other out. Therefore, from this age onwards, pregnant women are offered an amniotic fluid test.

The procedures in detail

Ultrasound (sonography): The first sign of trisomy 21 is often a thickened neck fold in the fetus (neck transparency test, neck fold measurement). This is a temporary swelling in the neck that occurs between the 11th and 14th week of pregnancy. It indicates a chromosomal disorder in the child.

In addition, the doctor uses ultrasound to identify internal and external malformations or peculiarities that may be caused by an extra chromosome 21. Examples are a shortened nose bone, a small head, short hands and feet or the gap in a sandal. With a special ultrasound method (Doppler sonography) the blood flow in the heart and the large heart vessels can be visualized. This enables the doctor to identify heart defects that are quite common in Down syndrome.

First trimester screening: Here certain measurement results from the ultrasound examination (including the neck transparency test), a blood test with the determination of two values (HCG and Papp-A) as well as individual risks such as the age of the mother or a family history are summarized. This gives a statistical value for the risk of trisomy 21 in the unborn child.

Triple test: First, three parameters are measured in the maternal blood serum - the child protein alpha-fetoproptein (AFP) and the maternal hormones estriol and HCG. From the measurement results, together with the age of the mother and the time of pregnancy, the risk of trisomy 21 in the child can be calculated.

Chorionic villus sampling: The chorionic villi are part of the placenta. A tissue sample is obtained from them for chromosome analysis. The chorionic villi have the same genetic material as the unborn child, because they also arise from the fertilized egg cell. The examination can be carried out from around the 11th week of pregnancy.

Amniocentesis (examination of the amniotic fluid): The doctor uses a fine hollow needle to take a sample of the amniotic fluid from the abdominal wall of the mother-to-be. Occasional child cells swim in it. Your genetic makeup can be examined in the laboratory for genetic disorders such as trisomy 21. An amniotic fluid test is not possible until the 14th week of pregnancy at the earliest.

Fetal blood collection: Here the doctor takes a blood sample of the unborn child from the umbilical cord (umbilical cord puncture). The cells contained are examined for their number of chromosomes. The earliest possible time for an umbilical cord puncture is around the 19th week of pregnancy.

PrenaTest and Panorama-Test

Until a few years ago, trisomies such as Down's syndrome in an unborn child could only be diagnosed using invasive methods of prenatal diagnosis (chorionic villus sampling, amniocentesis, fetal blood sampling). However, these procedures can cause a miscarriage when the sample is taken.

In the meantime, some special blood tests such as the PrenaTest or the Panorama test are available for diagnosing trisomies in unborn babies: They can also detect Down syndrome and other chromosomal disorders with a high degree of probability, but without increasing the risk of miscarriage.

The PrenaTest, the Panorama Test and similar blood tests are based on the fact that traces of the child's genome can also be detected in the blood of a pregnant woman. These "DNA snippets" from the unborn child can be filtered out and examined for Down syndrome and other chromosome abnormalities.

You can read more about these test procedures in the article PrenaTest and Panorama-Test.

Harmony test

Like the PrenaTest and the Panorama-Test, the Harmony-Test belongs to the non-invasive prenatal diagnosis (NIPD). It is also suitable for determining Down syndrome and other chromosomal abnormalities in the unborn child with a high degree of certainty.

The Harmony test (like comparable blood tests) is intended for pregnant women with an increased risk of chromosome abnormalities in the unborn child. This can be the case, for example, if the first-trimester screening has produced an abnormal result or if Down's syndrome or other chromosome abnormalities already occur in the family.

So far, the Harmony test and the other non-invasive blood tests for prenatal diagnostics have generally not been paid for by health insurance companies.

You can read everything you need to know about this blood test in the Harmony test article.

Down syndrome: treatment

The excess chromosome 21 can neither be blocked nor switched off - so Down's syndrome cannot be cured. Affected children benefit from consistent care and support. The aim is to reduce restrictions (such as problems with fine motor skills) and to fully exploit the individual development opportunities of children with Down syndrome. In addition, health problems associated with trisomy 21 should be treated as best as possible (e.g. heart defects).

The prerequisite for this is that targeted funding is started as early as possible. This increases the chance that children with trisomy 21 will later be able to lead a life that is as independent and independent as possible.

In the following you will find some examples of therapy and support options for Down syndrome. Each child should receive individual, appropriate treatment, tailored to their own needs.

surgery

Some organ malformations such as malformations in the rectum and heart defects can be corrected surgically. This can significantly improve the quality of life of those affected. Surgical intervention is also useful for orthopedic problems, for example in the case of unstable kneecaps or foot malformations.

Physiotherapy & occupational therapy

Physiotherapy (e.g. according to Bobath or Vojta) supports the motor development of Down syndrome children. The weak muscles and the loose connective tissue are strengthened and trained. The coordination of body movements and posture control can also be improved with suitable physiotherapeutic measures. Occupational therapy can also support the children's fine motor skills and perception.

The choice of therapist (the child must trust him or her) and an individually tailored therapy plan are decisive for the success of the treatment. It is also important that the exercises are approached in a playful way and that the child is not put under high pressure to perform.

Language training

Speech development in Down syndrome children can be promoted in several ways. With language and speaking exercises (at home as well as in their own language class - speech therapy) the children's communication and expression skills can be improved. It also helps when others speak to you slowly and clearly. It is best if signs support what is being said. Because visual impressions can be more easily memorized by children with Down syndrome than information that they only perceive through their ears. The use of signs can promote language acquisition from around the age of two.

Hearing impairment interferes with learning to speak. Therefore it should be treated early. The high, pointed palate typical of Down syndrome and misaligned teeth can be partly responsible if those affected speak difficultly. A dentist or orthodontist can help here (for example with a palate plate).

Spiritual and social advancement

Family and friends are very important to people with Down syndrome. It is in this environment that they can best learn and practice social behavior.

If possible, children with Down syndrome should attend an inclusive kindergarten. Such facilities accept both healthy children and children with physical or mental disabilities. In addition to educators, specially trained staff work there to provide targeted support to the children.

At school, children with Down syndrome often cannot keep up with the rest of the class. It takes longer and more practice to learn something new. A sensible alternative can be, for example, integration classes or schools for people with learning disabilities. In principle, however, all children in Germany have the right to attend regular schools. How successful this can be is shown by the example of the Spaniard Pablo Pineda, who studied psychology and education and became a teacher. He is Europe's first academic with Down's syndrome.

Patience and empathy

Children with Down syndrome are capable of learning - they just need a lot of time and empathy. They usually react very sensitively to pressure and excessive demands and turn away.

Concomitant diseases of trisomy 21 such as epilepsy, sleep apnea or leukemia are specifically treated.

Down syndrome: course and prognosis

Down syndrome can have very different effects on mental and physical development. In some cases, an independent life with Down syndrome is possible in adulthood. But there are also those affected who, due to severe intellectual disabilities, are dependent on permanent care for their entire life.

Individual early support and careful medical care from birth are also crucial for the good development of children with Down syndrome.

Down syndrome: life expectancy

The prognosis for Down syndrome depends primarily on the risk of leukemia and the type of heart defect. However, most heart defects can now be treated well. In addition, people with Down syndrome are more prone to infections. Because of these factors, the childhood death rate is highest. Adult people with Down syndrome age prematurely, and their mental performance declines early on. Despite everything, the life expectancy of those affected has increased in the last few decades - thanks to improved support and care as well as treatment of concomitant diseases. In 1929, Down syndrome children lived an average of only nine years old. In contrast, studies for 2002 showed an average life expectancy of 60 years.