What is Down’s syndrome?<\/strong> Not a disease, but an anomaly of the genetic make-up. This means that the genetic make-up of those affected deviates from the “normal state”.<\/li>\n
Causes: <\/strong>In all or some of the affected person’s body cells there are three (instead of two) copies of chromosome 21, which is why Down’s syndrome is also called trisomy 21.<\/li>\n
Frequency:<\/strong> most frequent deviation from the normal chromosome number (numerical chromosomal abnormality) It is estimated that one in 650 babies is born with Down syndrome. In Germany there are about 30,000 to 50,000 people affected.<\/li>\n
Typical symptoms:<\/strong> e.g. short head, flat back of the head, round and flat face, slanting eyes with delicate eye wrinkle in the inner corner of the eye, usually open mouth with increased salivation, four-finger furrow, sandal gap, dwarfism<\/li>\n
Possible consequences<\/strong> include heart defects, malformations of the digestive tract, orthopaedic problems (such as flat feet), hearing and vision problems, increased susceptibility to infections, sleep-related breathing disorders, increased risk of leukaemia, epilepsy, autoimmune diseases, autism, ADHD, etc., mental disability, but also special abilities such as musical talent<\/li>\n
Treatment options:<\/strong> targeted individual support (as early as possible), for example by means of physiotherapy, occupational therapy and speech therapy; surgical treatment of organ and skeletal deformities; treatment of concomitant diseases<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<\/section>\n\n
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Down syndrome: symptoms and consequences<\/h2>\n
People with Down syndrome (trisomy 21) can usually be recognised by their typical appearance<\/strong>. Characteristic Down syndrome symptoms are:<\/p>\n
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short head (Brachycephaly) with flat back of the head, short neck and round, flat face<\/li>\n
slightly slanting eyes with delicate skin fold at the inner corner of the eye (epicanthus)<\/li>\n
increased interpupillary distance<\/li>\n
light, white spots on the iris (“brushfieldspots”) – they disappear with increasing age and the incorporation of colour pigments into the iris<\/li>\n
radicle<\/li>\n
mostly open mouth and increased salivation<\/li>\n
furrowed tongue, which is often too large and protrudes from the mouth (macroglossia)<\/li>\n
narrow, high palate<\/li>\n
underdeveloped jaws and teeth<\/li>\n
little roundish ears, set low<\/li>\n
excess skin in the neck, short neck<\/li>\n
short wide hands with short fingers<\/li>\n
Four-finger furrow (transverse furrow on the palm of the hand, starting under the index finger and continuing to below the little finger)<\/li>\n
Sandal gap (large distance between first and second toe)<\/li>\n<\/ul>\n
Slanted eyes and a flat nose root are not only found in people with Down syndrome, but also in the Mongolian tribe. This is why Down syndrome was popularly known as “mongolism” in the past and the people affected were called “mongoloid”. At the moment of our latest update in 2020, these expressions are deprecated and not in use.<\/p>\n
Other Down syndrome characteristics are weakly developed muscles (low muscle tone) and delayed reflexes. The body growth of those affected is slowed down and they are below average in size (dwarfism). In addition, a pronounced weakness of the connective tissue makes the joints excessively mobile.<\/p>\n
Down syndrome: health consequences<\/h3>\n
Trisomy 21 can affect health. Particularly frequent trisomy 21 features are heart defects<\/strong>. They occur in about half of all people with Down syndrome. A common heart defect is the so-called AV channel (atrioventricular channel). This is a defect of the septum between the atria and the ventricles. It causes shortness of breath, growth disorders and recurrent pneumonia. In many cases, the cardiac septum between the heart chambers is also not completely closed (ventricular septum defect).<\/p>\n
Very often Down’s syndrome is also associated with malformations in the gastrointestinal tract<\/strong>, such as narrowing of the small intestine or malformations of the rectum. Hearing<\/strong> and vision<\/strong> problems are also common.<\/p>\n
Because the immune system is underdeveloped, those affected are more susceptible to infections<\/strong>, especially in the respiratory tract. For example, many Down’s syndrome children are prone to middle ear inflammation, bronchitis and pneumonia.<\/p>\n
Trisomy 21 is often accompanied by sleep-related breathing disorder<\/strong> (obstructive sleep apnea), sometimes accompanied by snoring: The upper respiratory tract relaxes and narrows during sleep, which results in brief breathing stops. Each time this happens, the oxygen saturation in the blood drops. The brain reacts to this with a wake-up impulse. However, those affected quickly fall asleep again and usually cannot remember the short waking phases the next day. However, they are often tired during the day because of the lack of restful continuous sleep.<\/p>\n
Another consequence of trisomy 21 is the increased risk of acute leukemia (a form of blood cancer<\/strong>): it is up to 20 times higher than in children without this chromosomal abnormality. There are several genes on chromosome 21 that play an important role in the development of leukaemia. Acute myelogenous leukaemia (AML) is more common in Down’s syndrome than acute lymphatic leukaemia (ALL) – in children without trisomy 21 it is exactly the opposite.<\/p>\n
In addition to leukemia, epileptic seizures<\/strong> (epilepsy) and autoimmune diseases<\/strong> are more common in Down’s syndrome than in the general population. The latter include, for example:<\/p>\n
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Diabetes mellitus type 1<\/li>\n
Celiac disease<\/li>\n
chronic rheumatic disease in childhood (juvenile rheumatoid arthritis, also called juvenile idiopathic arthritis)<\/li>\n
In addition, orthopaedic problems<\/strong> are often observed with trisomy 21. These include, for example, malpositions in the area of the neck and shoulder as well as the hip (hip dysplasia), an unstable patella and malformations in the area of the feet (such as flat feet).<\/p>\n
In addition, people with Down’s syndrome have an increased risk of behavioural or psychiatric disorders<\/strong>, such as ADHD, autism, anxiety disorders, emotional problems and even depression.<\/p>\n
Down syndrome also affects fertility<\/strong>: Male with trisomy 21 are usually infertile. Affected girls and women, on the other hand, are fertile (although limited). The probability that they will pass on the chromosomal abnormality to the unborn child during pregnancy is about 50 percent.<\/p>\n
Down’s syndrome: Mental impairment<\/h3>\n
Down syndrome is the most common cause of a congenital mental disability<\/strong>. Trisomy 21 children often learn to speak later than other children, partly because they usually hear worse. Even their language is therefore sometimes difficult to understand. In many cases, the people concerned need longer to understand a situation. They often find it difficult to retain what they have already learned when they have to learn something new. The motor development is delayed – the children start crawling or walking late.<\/p>\n
The intellectual abilities are more or less limited. Some of those affected are severely mentally impaired (but this is relatively rare), while others have almost average intelligence. The following applies: The mental development of a Down’s syndrome child does not only depend on its genetic make-up, but also on whether and to what extent it is supported.<\/p>\n
Down syndrome: special abilities<\/h3>\n
Trisomy 21 does not only mean malformations 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.<\/p>\n<\/div>\n<\/div>\n<\/section>\n\n
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Down syndrome: causes and risk factors<\/h2>\n
Down syndrome is caused by an error in the production of germ cells<\/strong> (eggs or sperm):<\/p>\n
Egg and sperm cells are created by cell division from precursor cells with a normal double set of chromosomes (chromosomes = carriers of genetic material). This double set of chromosomes comprises 22 paired autosomes plus two sex chromosomes (XX for women and XY for men). In total, there are 46 chromosomes.<\/p>\n
During the division process, the genetic information is normally distributed evenly among the germ cells that are created, each of which then has a simple set of chromosomes (22 autosomes and one sex chromosome = 23 chromosomes). Thus, in the case of later fertilisation, the fusion of egg and sperm cell can result in a cell with a normal double set of chromosomes, from which the child can then emerge through countless cell divisions.<\/p>\n
However, errors can occur when the 46 chromosomes are divided among 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 merges with another “normal” germ cell during fertilisation, the result is a so-called trisome cell<\/strong> – it contains three copies of the chromosome in question – i.e. a total of 47 chromosomes. In Down syndrome, chromosome number 21<\/strong> is present in triplicate (instead of duplicate)<\/strong>. Doctors differentiate between different forms of Down syndrome<\/strong>: free trisomy 21, mosaic trisomy 21 and translocation trisomy 21.<\/p>\n
Free trisomy 21<\/h3>\n
Here, all body cells are equipped with a third chromosome 21. This is almost always a spontaneous new mutation. This means that free trisomy 21 usually occurs by chance, i.e. without any apparent reason. About 95 percent of<\/strong> all people with Down syndrome have a free trisomy. This is by far the most common variant of chromosomal defects.<\/p>\n