Down syndrom

Quick Overview

• What is Down Syndrome? No disease, but an anomaly of the genome. This means that the genetic make-up of those affected deviates from the “normal state”.
• Causes: In all or some of the body cells of those affected, there are three (instead of two) copies of chromosome 21. Therefore, the Down syndrome is also called trisomy 21.
• Frequency: most common deviation from normal chromosome number (numerical chromosome anomaly). An estimated one in every 650 babies is born with Down syndrome. About 30,000 to 50,000 people live in Germany.
• Typical symptoms: et al short head, flat back of the head, round and flat face, slanting eyes with a delicate eye fold in the inner corner of the eye, usually open mouth with increased salivation, four-finger furrow, sandal gap, short stature
• Possible consequences: et al Heart defects, malformations in the digestive tract, orthopedic problems (such as flatfoot), hearing and vision disorders, increased susceptibility to infections, sleep-disordered breathing, increased risk of leukemia, epilepsy, autoimmune diseases, autism, ADHD, etc., mental disabilities, but also special skills such as musical talent
• Treatment options: targeted individual support (as early as possible), for example by means of physiotherapy, occupational therapy and speech therapy; operative treatment of organ and skeletal malformations; Treatment of comorbidities

Down syndrome: symptoms and consequences

People with Down’s Syndrome (trisomy 21) are usually on their own typical appearance detect. Characteristic Down syndrome symptoms are:

• short head (brachycephaly) with flat back of the head, short neck and round, flat face
• slightly oblique eyes with a delicate skin fold on the inner corner of the eye (epicanthus)
• increased eye relief
• bright, white patches of the iris (“brushfieldspots”) – they disappear with age and the incorporation of color pigments in the iris
• flat, broad nose root
• usually open mouth and increased salivation
• grooved tongue, which is often too big and protrudes from the mouth (macroglossia)
• narrow, high palate
• underdeveloped jaws and teeth
• small, low-set, round ears
• excess skin on the neck, short neck
• short broad hands with short fingers
• Fourfinger furrow (transverse furrow on the palm of the hand, starting under the forefinger and continuing to below the little finger)
• Sandalenlücke (large distance between first and second toe)

Oblique eyes and a flat nose root are found not only in people with Down syndrome, but also in the tribe of the Mongols. Therefore, Down’s syndrome was popularly referred to earlier as “Mongolism” and those affected as “Mongoloid”. For ethical reasons, you should not use these terms anymore.

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

Down syndrome: health consequences

Trisomy 21 can affect your health. Particularly common trisomy 21 features are cardiac defect, They are found in about half of all people with Down syndrome. A common heart defect is the so-called AV (atrioventricular) channel. This is a septal defect between the atria and ventricles. It causes respiratory distress, stunted growth and recurrent pneumonia. In many cases, the cardiac septum between the heart chambers is not completely closed (ventricular septal defect).

Very often, Down syndrome is synonymous with Malformations in the gastrointestinal tract connected, such as narrowing of the small intestine or malformations of the rectum. Also hearing impairment and blurred vision are common.

Because the immune system is underdeveloped, those affected are more susceptible to infections, especially in the respiratory tract. For example, many Down Syndrome children are prone to middle ear infection, bronchitis and pneumonia.

The Trisomy 21 is in many cases with a sleep-disordered breathing (Obstructive sleep apnea), sometimes accompanied by snoring: The upper respiratory tract becomes slack and narrowed during sleep, resulting in short respiratory bursts. Each time, the oxygen saturation in the blood drops. The brain reacts with a wake-up pulse. Those affected fall asleep quickly and can not remember the next day most of the short waking phases. But they are often tired during the day, because the restful sleep is missing.

Another consequence of trisomy 21 is the increased risk of acute leukemia (a form of blood cancer): It is up to 20 times more than in children without this chromosomal abnormality. On chromosome 21 there are several genes 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, too epileptic seizures (Epilepsy) as well Autoimmune diseases in Down syndrome more common than in the normal population. The latter include, for example:

• Diabetes mellitus type 1
• 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, trisomy 21 is often observed orthopedic problems, These include, for example, malpositions in the area of ​​the neck and shoulder as well as on the hip (hip dysplasia), an unstable patella and malformations of the feet (such as flat foot).

In addition, people with Down syndrome have an increased risk for Behavioral problems or psychiatric conditions, for example, ADHD, autism, anxiety disorders as well as emotional problems and depression.

Down syndrome also affects the fertility out: Boys or men with trisomy 21 are usually infertile. Affected girls and women are fertile (albeit limited). The probability that they pass on the chromosome anomaly to the unborn child during pregnancy is about 50 percent.

Down syndrome: mental limitations

Down’s syndrome is the most common cause of a congenital mental disability, Trisomy 21 children often learn to speak later than other children, partly because they usually hear worse. Their language is therefore sometimes difficult to understand. In many cases, those affected need more time to understand the facts. Those who have already learned something often have a hard time learning new things. The motor development is delayed – the children start crawling or walking late.

The intellectual abilities are more or less restricted. Some sufferers are severely mentally impaired (which is relatively rare), while others are almost average-minded. The following applies: The mental development of a Down syndrome child depends not only on its genetic make-up, but also on whether and to what extent it is promoted.

Down syndrome: special skills

Trisomy 21 does not just mean birth defects and limitations. People with Down syndrome have strong emotional abilities and a sunny nature: they are affectionate, tender, friendly and cheerful. In addition, many are musically talented and have a strong sense of rhythm.

Down syndrome: causes and risk factors

Down’s syndrome is on one Error in the production of germ cells (Ova or sperm):

Egg and sperm cells are formed by cell division from progenitor cells with normal double chromosome set (chromosomes = carrier of the genetic material). This double set of chromosomes includes 22 paired autosomes plus two sex chromosomes (XX in women and XY in men). Altogether that means 46 chromosomes.

The genetic information is normally distributed evenly over the developing germ cells during the process of division, which then each have a simple set of chromosomes (22 autosomes and one sex chromosome = 23 chromosomes). Thus, in a later fertilization by the fusion of egg cell and sperm again a cell with normal double set of chromosomes arise, from which then emerges over countless cell divisions of the child.

However, when dividing the 46 chromosomes into the resulting germ cells, mistakes can happen: sometimes the two copies of a chromosome accidentally end up in the same new germ cell. This then has a total of 24 instead of 23 chromosomes. If it melts later in the fertilization with another “normal” germ cell, the result is a so-called trisome cell – It contains three copies of the chromosome in question – for a total of 47 chromosomes. Down syndrome is Chromosome number 21 in triple (instead of twice) version available. Here are different doctors different forms of Down syndrome: Free trisomy 21, mosaic trisomy 21 and translocation trisomy 21.

Free Trisomy 21

All body cells are equipped with a third chromosome 21. It is almost always a spontaneous new mutation. That is, the free Trisomy 21 usually arises at random, that is, for no apparent reason. Approximately 95 percent All people with Down syndrome have a free trisomy. This is by far the most common variant of the chromosomal disorder.

Mosaic trisomy 21

Sometimes the supernumerary third chromosome 21 is lost in cell divisions during embryonic development in one cell (“trisomy rescue”), but not in others. This means that in the episode “normal” and trisome cell lines develop. So the child’s body consists of cells with 46 and those with 47 chromosomes.

The same result occurs when the fertilization proceeds regularly (the fertilized egg cell has 46 chromosomes), but in the subsequent embryonic development a mistake happened: In the division of a single cell accidentally three chromosomes 21 in a daughter cell (and only one copy in the second daughter cell). Here, too, both “normal” and trisome cell lines develop.

The mosaic trisomy comes at about two percent of all people with Down syndrome. Depending on whether the person has more “normal” or more trisome cells, the Down syndrome characteristics are different pronounced.

Translocation trisomy 21

This form of Down syndrome usually has its origin in a parent with so-called “balanced” translocation 21. This means that the affected parent normally has two copies of chromosome 21 in its body cells. However, one of them is attached to another chromosome (translocation). For the parent itself, this has no consequences. When a child is conceived, 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 that results from a balanced translocation of a parent may be more prevalent in a family. This means that several children of the affected parent may have Down syndrome (in the form of translocation trisomy 21).

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

The translocation trisomy 21 does about three percent of all cases of Down syndrome.

Down syndrome: risk factors

In principle, there is a possibility for every pregnancy that the child is born with Down syndrome (or another genetic disorder). With increasing age of the mother but increases the probability of it. In 35- to 40-year-old women, 1 out of every 260 children born with trisomy 21. For 40- to 45-year-old pregnant women, the ratio is already at 1 in 50.

Scientists suspect that ovarian division is more susceptible to disorders as the woman ages. This could make it easier to make mistakes in dividing the chromosomes. Whether the father’s age also plays a role is controversial.

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

Down syndrome: examinations and diagnosis

In the context of prenatal diagnosis, it can be determined before birth whether a child has Down syndrome (or another chromosome disorder or genetic disease). Several methods of investigation are possible:

The so-called non-invasive procedure such as the first-trimester screening (ultrasound and blood test) and the triple test (blood test) are risk-free for both mother and child. First trimester screening in particular (at the end of the first trimester of pregnancy) provides good evidence for a trisomy 21 in the unborn child, but does not allow a reliable diagnosis. As a result, the screening provides only an estimate of the risk of “unbalanced” Down Syndrome.

To safely diagnose Down syndrome, one is direct analysis of the chromosomes of the child necessary. The sample material is obtained from a tissue sample from the Mutterkuchen (chorionic villus sampling), an amniocentesis (amniocentesis) or a Fetalblutentnahme (umbilical cord puncture). All three procedures are surgery on the womb (invasive methods). They are associated with a certain risk for the child. Therefore, they are used only in specific suspected cases, such as when the ultrasound is unclear. Even in pregnant women The risk of miscarriage as a result of the procedure and the risk of Down syndrome from the age of 35 years cancel each other out. That is why pregnant women are offered an amniocentesis examination from this age onwards.

The procedures in detail

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

In addition, the doctor detects ultrasound internal and external malformations or peculiarities that may be caused by a supernumerary chromosome 21. Examples include a shortened nasal bone, a small head, short hands and feet or the sandal gap. With a special ultrasound procedure (Doppler sonography), the blood flow in the heart and the large heart vessels can be represented. So the doctor can detect heart defects that are quite common in Down’s syndrome.

First Trimester Screening: Here, certain measurement results from the ultrasound examination (among other things, nuchal translucency test), a blood test with the determination of two values ​​(HCG and Papp-A) and individual risks such as the age of the mother or a family history are summarized. This results in 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 can be calculated together with the age of the mother and the time of pregnancy, the risk of a trisomy 21 in the child.

chorionic villus sampling: The chorionic villi are a part of the nut cake (placenta). From them, a tissue sample for a chromosome analysis is obtained. The chorionic villi have the same genetic material as the unborn child because they also originate from the fertilized egg cell. The examination can be carried out approximately from the 11th week of pregnancy.

Amniocentesis (amniotic fluid examination): The doctor removes a sample of the amniotic fluid with a fine hollow needle over the abdominal wall of the expectant mother. Sporadically, infantile cells swim in it. Their genetic material can be examined in the laboratory for genetic disorders such as trisomy 21. An amniotic fluid examination is possible at the earliest from the 14th week of pregnancy.

Fetalblutentnahme: Here, the doctor from the umbilical cord wins a blood test of the unborn child (umbilical cord puncture). The cells are examined for their chromosome number. The earliest possible time for an umbilical cord puncture is around the 19th week of pregnancy.

PrenaTest and panoramic 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 methods can cause a miscarriage during sampling.

Meanwhile, some special blood tests such as the PraenaTest or the Panorama test are available for the diagnosis of trisomies in unborn babies: they can also detect Down syndrome and other chromosomal disorders with high probability, but without increasing the risk of miscarriage.

The PrenaTest, the panoramic test and similar blood tests are based on the fact that in the blood of a pregnant woman also traces of the child’s genome can be detected. These “snippets of DNA” from the unborn child can be filtered out and examined for Down syndrome and other chromosome aberrations.

Read more about these tests in the article PraenaTest and Panorama-Test.

Harmony test

The Harmony test belongs to the PrenaTest and the Panorama Test for Non-invasive Prenatal Diagnosis (NIPD). It is also useful for detecting Down syndrome and other chromosome abnormalities in the unborn child with high certainty.

The Harmony test (like comparable blood tests) is designed for pregnant women at increased risk for fetal chromosome abnormalities. This may be the case, for example, if first-trimester screening has produced a conspicuous result or if Down syndrome or other chromosome aberrations already exist in the family.

So far, the Harmony test and the other non-invasive blood tests of prenatal diagnosis are usually not paid by the health insurance companies.

Read all about this blood test in the article Harmony Test.

Down syndrome: treatment

The excess chromosome 21 can neither block nor switch off – so the Down syndrome is not curable. However, affected children benefit from consistent care and support. The goal is to reduce limitations (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 best treated (eg, heart disease).

The prerequisite is that with the targeted promotion as early as possible is started. This increases the chance that children with trisomy 21 can later lead an independent and independent life.

Below are some examples of treatment and support options for Down syndrome. Each child should receive an individual appropriate treatment, tailored to their own needs.

surgery

Some organ malformations such as malformations of the rectum and heart defects can be corrected surgically. This can significantly improve the quality of life of those affected. Even with orthopedic problems, a surgical procedure is often useful, for example, in unstable kneecap or Fußfehlbildungen.

Physiotherapy & Ergotherapy

Physiotherapy (for example after Bobath or Vojta) supports the motor development of Down syndrome children. The weak musculature and the too loose connective tissue are strengthened and trained. Coordination of body movements and postural control can also be improved with appropriate physiotherapy. Occupational therapy can also support fine motor skills and the perception of children.

Decisive for the success of the treatment are the selection of the therapist (the child must trust him or her) as well as an individually tailored therapy plan. It is also important that the exercises are tackled playfully and the child is not put under high pressure to perform.

language support

Speech development in Down syndrome children can be promoted in several ways. With Speech and speech exercises (at home and in their own language lessons – speech therapy) can improve the communication and expressiveness of the children. It also helps when others talk to them slowly and clearly. It is best if gestures to support what has been said. For visual impressions are easier to memorize children with Down syndrome than information that they can only absorb through their ears. The use of gestures can promote language acquisition from about the age of two.

A hearing impairment interferes with speaking. Therefore, it should be treated early. The typical for Down syndrome high, pointed palate such as Malocclusions can be jointly responsible if those affected speak difficult to understand. A dentist or orthodontist can help here (for example with a palate plate).

Spiritual and social promotion

Your own family and friends are very important for people with Down syndrome. In this environment, they can best learn and practice social behaviors.

If possible, children with Down syndrome should attend an inclusive kindergarten. Such facilities include both healthy and children with physical or mental limitations. In addition to educators, there are specially trained specialist staff who specifically support the children.

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

Patience and empathy

Children with Down syndrome are able to learn – they only need a lot of time and empathy. On pressure and excessive demands, they usually react very sensitively and turn away.

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

Down syndrome: history and prognosis

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

Decisive factors for a good development of children with Down syndrome are always an individual early intervention and a careful medical care from birth.

Down syndrome: life expectancy

The prognosis for Down’s syndrome depends mainly on the risk of leukemia and the nature of the heart defect. However, most heart defects can be treated well today. In addition, people with Down syndrome are more prone to infections. Because of these factors, the mortality rate is highest in childhood. Adult people with Down’s syndrome age prematurely and their mental capacity drops early. In spite of everything, the life expectancy of those affected has increased in recent decades – thanks to improved promotion, care and treatment of comorbidities. In 1929 was Down syndromChildren on average only nine years old. By contrast, studies for the year 2002 showed an average life expectancy of 60 years.

Additional information

Guideline:

• Guideline “Down syndrome in childhood and adolescence” of the German Society for Paediatrics (2016)

Support Groups:

• Working group DOWN syndrome e.V.
• Down Syndrome Network Germany e.V.