Down syndrome is among the most common syndromes caused by a numerical chromosomal anomaly associated with mental retardation and a typical appearance – it accounts for more than 5% of all mental retardations. Thanks to modern methods of prenatal diagnosis, this syndrome can usually be detected already during pregnancy, but there is no cure. How does Down syndrome arise, how does it manifest itself and what are the possibilities of targeted care for a better quality of life with this diagnosis?
Contents: Down syndrome – causes, manifestations and targeted care
What is Down syndrome and how does it occur?
Incidence and causes of Down syndrome
Types of Down syndrome
Symptoms of Down syndrome
Mental disability and behavior
Diagnosis of Down syndrome
Life and upbringing of children with Down syndrome
Down syndrome in a nutshell
Statistics indicate that there is one case of Down syndrome in every 800 to 1,000 newborns . The average lifespan here is between 40 and 60 years .
What is Down syndrome and how does it occur?
Down’s syndrome is the most common congenital chromosomal anomaly , which is caused by an excess of one chromosome in the karyotype, specifically the 21st chromosome . Each cell thus contains three chromosomes 21, instead of the usual pair – i.e. 2 chromosomes. That is why Down’s syndrome is also called trisomy 21 for short . To be brief – the nucleus of each cell contains 46 chromosomes, or 23 pairs (karyotype).
Incidence and causes of Down syndrome
Down syndrome occurs worldwide, regardless of geographic, national, ethnic or other differences. It is proven that the behavior of parents before or during pregnancy does not affect its occurrence or increase the probability of its occurrence.
Down’s syndrome is therefore considered a random phenomenon during cell division, and the only proven factor related to an increase in the probability of its occurrence is above all the older age of the mother – over 35 years. The exception is the rarer cases of translocation, when chromosome 21 is linked to another chromosome and one of the parents can be the carrier of this aberration, even if he himself is completely healthy and usually does not know about this abnormality in his karyotype at all, explains RNDr . Magdalena Uvírová, Ph.D., director of EUC Laboratory CGB.
Statistics indicate that there is one case of Down syndrome in every 800 to 1,000 newborns . The average lifespan here is between 40 and 60 years . The causes of death are often associated with, for example, congenital heart defects, an increased risk of leukemia and other complications related to this syndrome.
Types of Down syndrome
The effect on the symptoms of Down syndrome is very similar for all these types. E.g. however, a person with mosaic Down syndrome may not have as many symptoms, as the extra chromosome is only present in some cells in this case.
· Trisomy 21 (nondisjunction)
The most common type (93% of cases), where each cell in the body has three 21st chromosomes instead of two.
· Translocation Down syndrome
It occurs more rarely (about 4% of cases) and occurs when an extra part of the 21st chromosome joins another chromosome (most commonly the 14th chromosome). Here, one of the parents may be a carrier of Down syndrome.
· Mosaicism
It occurs very rarely (about 1% of cases). The anomaly here arises only during later division, therefore the extra chromosome is present only in some cells of the body. This is the rarest type, where only some cells have an extra 21st chromosome.
Symptoms of Down syndrome
Overall, we can summarize that the manifestations of Down syndrome can be variable , with the greatest variability being in mosaic forms. In addition to mental retardation, there is no symptom that must always occur, at the same time there is no connection between the number of external symptoms and the degree of mental retardation.
· Main physical features
- Head, neck and hair– the braincase is small, round, with a flat crown, abnormal or missing nasal bone. Newborns may have loose skin on the back of the neck that smoothes out as they grow. Older children and adults tend to have short and wide necks, hair is fine and usually straight.
- Face– usually round, flattened in profile. The ears are set low, the mouth is remarkably small with thick lips, the tongue is on the contrary enlarged, the nose is shorter and with a wide root.
- Eyes– the slight tilt here is caused by the skin fold of the upper eyelid covering the inner corner of the eye (epicanthus) and the upward-facing fissure. There may be white or yellowish dots on the edge of the iris. Furthermore, a greater distance between the inner corners of the eyes (hypertelorism) is typical.
- Limbs– hands tend to be wide, short, with short fingers and the little finger may have only one joint. A transverse groove (the so-called four-finger or monkey groove) appears more rarely on the palm. The feet tend to be more massive, sometimes with a gap between the thumb and index finger (the so-called sandal groove).
- Muscle tension– generalized muscle hypotonia is common here, where the limbs and neck have reduced muscle tension.
- Character– skeletal anomalies, or short stature, lower weight, hyperextension of the joints, horizontal positioning of the sockets of the hip joints, deformity of the hip (coxa valga) are also typical.
· Health complications
- congenital heart defects;
- hearing loss, impaired vision, cataracts;
- leukemia (up to 30x higher risk of occurrence);
- chronic constipation ;
- sleep apnea (interruption of breathing during sleep);
- hypothyroidism (low thyroid function);
- obesity ;
- late teething (causes chewing problems);
- greater susceptibility to infections (respiratory tract, urinary tract, skin infection);
- Alzheimer’s disease in later life;
- other developmental defects of organs (stenosis of the duodenum, annular pancreas, annular pancreas, anal atresia and others);
- complete infertility in men, exceptional fertility in women.
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Mental disability and behavior
Down syndrome most often causes mild (IQ 50-70 points) or moderate (IQ 35-50 points) mental retardation. However, there are exceptions, when people with Down syndrome can move on the border of the normal range (IQ around 80 points), while others suffer from severe or profound mental retardation (IQ 20 to 35 or lower).
There are basically two opposing views regarding the behavior of children and adults with Down syndrome . According to the first, they are calm and easy-to-manage individuals, and according to the second, on the contrary, they are hard-to-manage wayward beings.
A child with Down syndrome is more developmentally delayed. Compared to other children, his behavior does not correspond to his age or physical fitness. E.g. the period of defiance, which normally manifests itself between the ages of 2 and 4, appears here rather around the age of 4, when the child is already bigger and stronger. Basically, however , there are no specific educational problems that would be related exclusively to the diagnosis of Down syndrome.
Diagnosis of Down syndrome
Down’s syndrome can only be accurately diagnosed by examining a sample of the placenta (chorionic villi) or amniotic fluid , which, of course, carries certain risks associated with the loss of the fetus, says MUDr. Faithful.
In addition to this method, the risk of its occurrence can also be determined by screening , which is carried out between the 11th and 13th weeks of pregnancy. The examination also includes a DNA analysis from the mother’s blood and a detailed ultrasound examination of the fetus. In the case of a positive finding, the finding is verified by genetic examination – determination of the karyotype of the fetus from the chorionic villi or amniotic fluid, and in the case of confirmation of trisomy of chromosome 21, the mother is offered an immediate termination of pregnancy. Down syndrome in pregnancy has no visible symptoms.
· Test for Down syndrome
The test is performed non-invasively and painlessly from the mother’s blood, in addition to Down syndrome, the test also recognizes Edwards and Patau syndrome. For now, unfortunately, this is not a 100% method to recognize the syndrome. Its reliability is reported to be between 97.5 and 99%.
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Down syndrome cannot be cured . However, its consequences and mental level can be positively influenced by targeted care. Studies show that people with Down syndrome achieve the best results especially in the loving and stimulating environment of their families .
Life and upbringing of children with Down syndrome
Down syndrome cannot be cured . However, its consequences and mental level can be positively influenced by targeted care. Studies show that people with Down syndrome achieve the best results especially in the loving and stimulating environment of their families . There are also noticeable differences between the current generation growing up in families and the earlier generation of so-called institutionalized children.
It is stated that the first 3 years of life play a crucial role in the development of children, which of course also applies to children with Down syndrome. Immediately after birth, it is appropriate to give them overall more intensive care. The experiences of parents and experts show that the development of children with Down syndrome usually proceeds quite normally. However, it is more demanding, more lengthy, slower, and any progress compared to other children is the result of intensive practice and targeted educational guidance.
In general, the basic diagnosis mainly affects motor and speech development. In the emotional and social sphere, on the other hand, children with Down syndrome often surpass their “normal” peers.
With the right guidance, necessary rehabilitation and special help with education, they will learn everything they need (from self-care, reading, writing to pursuing hobbies) and can thus lead an active and satisfied life . However, preparation for it here takes longer, requires increased effort, work and constant repetition.
Down syndrome in a nutshell
Down syndrome is the most common chromosomal abnormality, which is caused by the presence of an extra 21st chromosome. This causes developmental changes and some typical physiological signs. The severity of Down’s syndrome can be different for individuals, and it always entails a varying degree of mental disability, or other health complications (e.g. congenital heart defects or disorders of the digestive tract).
