Down syndrome: 21 things to know about this condition

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World Down Syndrome Day

On March 21, World Down Syndrome Day is celebrated, a condition characterized by a chromosomal abnormality that affects chromosome 21.

We have tried to shed some light on some of the aspects (21 in all) of this condition, including with the help of the pediatrician Diletta Valentini, who follows children with the syndrome at the Bambino Gesù Children's Hospital in the city, and the researcher Laura Cancedda, which at the Del Paeseno Institute of Technology in Genoa and for the Telethon Dulbecco Institute deals with the molecular mechanisms of the syndrome. We see.

1. What is Down syndrome

It is a syndrome of genetic origin, caused by an anomaly affecting chromosome number 21 and characterized by a set of both physical and cognitive symptoms. It is the most common cause of intellectual disability in the world and is associated with physical characteristics very specific: round face, elongated and slanted eyes, small nose and ears, short stature, poor muscle tone, stubby hands.

2. Who discovered it

The first to describe the common features of the syndrome was the English doctor in the mid-nineteenth century John Langdon Down, from which the condition takes its name. The French geneticist discovered that it was caused by the presence of an extra chromosome in the XNUMXs. Jerome Lejeune.

3. What are the causes

Normally each cell in our body (apart from the sex cells, i.e. oocytes and spermatozoa) has 23 pairs of chromosomes for a total of 46 chromosomes. Typically, Down syndrome is due to the presence of an extra copy of chromosome 21: there are therefore three copies of this chromosome instead of two and for this reason we also speak of trisomy 21. Sometimes the tripling of genetic material does not affect chromosome 21 in its entirety, but only a part of it.

Other times - but this happens much more rarely - it may happen that only some cells of a person have a condition of trisomy 21, while other cells have the normal set of 46 chromosomes. In this case we speak of mosaicism.

4. What causes trisomy

As a fact sheet on the Telethon Foundation website explains, generally "the genetic defect is congenital but not hereditary". It means that the trisomy is not present in the parents but arises spontaneously during the development of sexual cells (gametes) or immediately after conception, due to errors that affect the duplication phase of the genetic material during cell division or its breakdown in cells daughters.

In the vast majority of cases, the gametes involved are the oocytes, but in about 10% of cases the anomaly concerns the spermatozoa.

We know that the frequency of these anomalies increases with the age of the mother, with ever increasing values ​​starting from the age of 35. We are trying to understand if others also exist risk factors.

5. How many people do you care

It is estimated that, in the world, one child with Down syndrome is born for every 1000-1100 children (data from the World Health Organization), for a total of about 3000-5000 new borns a year with the syndrome.

As regards the country, the estimate is one born with the syndrome for every 1200 children. In our country there are currently about 38 people with this condition, with an average age of 25 years.

Listen to the interview with Giacomo Mazzariol, author of the book "My brother chases dinosaurs". A text that talks about Down syndrome and acceptance and rediscovery by a teenager.

6. How the diagnosis is made

As the Telethon fact sheet explains, "today most of the diagnoses take place in prenatal period. Some ultrasound parameters (such as nuchal translucency) allow suspicion of the presence of the syndrome already in the first months of pregnancy. This can then be confirmed with techniques such as villocentesis or amniocentesis which allow to obtain the map of the chromosomes of the fetus (karyotype) ".

Read also: Choosing the prenatal diagnosis: screening tests, fetal DNA tests and amniocentesis / villocentesis

After birth, the diagnosis is made by the neonatologist starting from observations relating to some characteristics of the baby, and confirmed by the genetic investigation of the baby's chromosomes (the karyotype)

7. What is the life expectancy

Thanks to medical advances, which make it possible to correct any important malformations, for example in the heart, and to follow any other complications over time, today the life expectancy of people with Down syndrome has radically changed. If only 100 years ago the average survival was 10 years, today in the world 80% of people with this syndrome are over 50.

In Del Paese it is estimated that the average survival is 62 years.

8. The cognitive aspect: intellectual disability

"Down syndrome is always characterized by cognitive retardation, which can be of different degrees, however, "says Diletta Valentina, pediatrician in charge of the Center dedicated to children and young people with Down syndrome at the Bambino Gesù Hospital in the city.

In particular, the cognitive areas most affected by the delay are the the memory and language. People with Down syndrome have difficulty remembering facts, events, concepts, experiences (long-term memory), but also small information that can be useful for a certain task (short-term memory, for example remembering numbers a phone number to be able to type them). From the point of view of language, however, the main problems are the delay in the acquisition of the classic stages of development, the difficulties in the emission of sounds and those in the acquisition and maintenance of grammar and syntax rules. These disabilities can severely compromise the abilities of school learning.

9. Cognitive retardation does not necessarily mean a lack of autonomy

"But be careful: beyond the degree of cognitive retardation that we can measure with specific tests, what is really important is the level of autonomy that individuals can achieve, and which in many cases is really high" underlines Valentini. "If a person is able to take the subway to go to school, work or eat pizza with friends, if he knows how to get change after shopping, all in all it matters how his cognitive delay was quantified" .

10. Behavioral disorders

"We don't know exactly why, but people with Down syndrome tend to be more prone to developing autism spectrum disorders," Valentini says. Basically: not all children with this syndrome will also have autism, but the likelihood of having it is higher than in the general population.

11. Down syndrome and Alzheimer's

The same is true for Alzheimer's disease. "It is well documented - explains the specialist - that compared to the general population, people with Down syndrome have a greater predisposition to develop Alzheimer's disease as early as around the age of 50. Also in this case, it is not yet clear why. of this association and we are trying to understand it ".

12. Effects on health and possible complications

According to Valentini, from a strictly medical point of view "Down syndrome can be considered one complex chronic disease, in the sense that it is associated with the possibility of manifesting, already at birth, some malformations, or of developing, in the course of life, various and different diseases ".

For example, 40-50% of children present congenital heart malformations, and very common are also the intestinal malformations, for example the narrowing of the duodenum. "The good news is that these malformations are corrected surgically immediately after birth or in the first months or years of life, which has allowed for a significant lengthening of life expectancy", emphasizes the doctor. Furthermore, 60 to 80% of children have problems with hearing and many have problems with view.

Among the various conditions and diseases that can occur in the course of life are: hormonal disorders, such as hypothyroidism and diabetes, predisposition to infections, constipation, gastroesophageal reflux, celiac disease, orthopedic abnormalities such as flat foot, epilepsy, sleep apnea and other sleep disorders , autoimmune diseases, obesity, some skin disorders, leukemia, Alzheimer's disease.

"Obviously it does not mean that all people with Down syndrome will have these malformations and become ill with these diseases, but it does mean that they are at a higher - sometimes much higher - risk than the general population of having them or developing them over the course of their lives. "explains Valentini. In short, someone may have more problems, someone else less but it is inevitable to take into account a multiplicity of health issues to be kept under strict control.

13. Children with Down syndrome and vaccinations

"People with Down syndrome have significant changes in the immune system, which sometimes works too much, leading to autoimmune diseasesi, and at other times it works too little, leading to increased susceptibility to infections, to which a particular anatomical conformation contributes, as in the case of otitis, "explains Valentini.

Because of this "immune deficiency", parents of children with the syndrome sometimes think it is better to avoid vaccinations. "Quite the opposite," the pediatrician says firmly. "Precisely because the immune system works poorly, it is necessary to put it in the best conditions to work better. Vaccinations are very important, and we know that children with Down's syndrome respond well, so my invitation is to do all the foreseen, mandatory and recommended ones, including the flu. "

Read also: Compulsory and voluntary vaccinations, the calendar

14. What to expect in the first months and years of a child with Down's syndrome

As we have seen, there may be congenital malformations, which must be treated in the appropriate ways and times. Aside from that, children with Down syndrome tend to present with a delay in motor development, due to poor muscle tone - hypotonia or, as Valentini says, excessive "softness" of the child - and a delay in language acquisition and development, which depends on a combination of various factors: hypotonia of the mouth muscles, but also difficulties with memory and possibly hearing disorders.

"For example, if usually around the year a child begins to take its first steps, in the case of a child with Down syndrome it can be done even around the age of two" explains Valentini. However, underlining that there are no precise rules. "In some cases, adequate rehabilitation therapy it allows you to reach the planned stages more quickly, perhaps in line with the general population. "In other cases, if the hypotonia is particularly pronounced, it may take much longer.

Always because of the hypotonia, which it can cause difficulty swallowing and chewingMany babies with Down syndrome also have difficulty feeding, whether it is breastfeeding or formula or solid feeding. In the first years of life they can therefore be underweight, while as they grow the risk of obesity increases, due to the combination of a poor quality diet (also because they may tend to prefer drinks and soft foods that are very caloric) and a certain tendency to sedentary lifestyle.

To better address these difficulties, rehabilitation therapy is essential, to be started as soon as possible. Let's talk about psychomotor skills, physiotherapy and speech therapy which, by strengthening the muscles of the mouth with specific exercises, not only promotes the acquisition of language but also allows the child to eat better. "It is important to start them as soon as possible" remembers Valentini. "The more these children are helped and stimulated, the better the results they can get."

15. The therapies

There is no definitive cure for Down syndrome. On the other hand, it is not a disease, but a condition characterized by multiple aspects, which must be addressed one by one, with the most appropriate tools, whether it is cardiac surgery for cardiac malformations or rehabilitation therapy to promote muscle development.

In addition to this, of course, individual medical conditions must be addressed, if and when they arise.

16. How people with Down syndrome should be followed medically

The ideal would be to take charge by a health worker who can have an overview of the person, and take into account all the various and multiple manifestations of the syndrome.

People with Down syndrome can be cured by a variety of specialists, from the orthopedist to the immunologist, from the cardiologist to the endocrinologist and so on. Each, by definition, focuses on his sector but tends to neglect the person as a whole, but the ideal would be to have someone who then pulls the strings completely. Exactly what happens in the Centro del Bambino Gesù directed by Diletta Valentini, and which however, all in all, represents an exception. In fact, in general, children and adults with Down syndrome in Del Paese are followed either by neuropsychiatrists or by medical geneticists.

From this point of view, the new model for taking care of people with chronic diseases, launched in the first months of this year, could represent a significant novelty in Lombardy, which provides for the identification of a "trusted medical manager. "that coordinates all the necessary health interventions.

17. The importance of periodic checks

"Children, teens and adults with Down syndrome should undergo periodic medical checks not only to monitor any diseases that have already arisen and are already known, but also to intercept the onset of any diseases whose initial symptoms may be masked by other characteristics. typical of the syndrome "explains Diletta Valentini.

For example, one of the typical symptoms of hypothyroidism is the constipation, but people with Down syndrome already suffer from this condition for a variety of other reasons such as muscle hypotonia, the fact that they tend to drink little and eat little fiber, and a sedentary lifestyle. "That's why the guidelines of the American Association of Pediatricians recommend having a thyroid test every year." Ditto for celiac disease, which can manifest itself with nonspecific symptoms such as anemia or alopecia (patchy hair loss). "But again, people with Down's syndrome can have alopecia, or they can be anemic all the time from an unbalanced diet."

18. The importance of nutrition

Sometimes we hear about the potential beneficial effects of certain substances, for example antioxidants or green tea, on the cognitive aspects of Down syndrome. But let's face it right away: they are effects perhaps observed in experiments conducted on animal models under particular controlled conditions and yet to be demonstrated in humans. "Unfortunately, there are no miraculous foods capable of affecting the intellectual disability of Down's syndrome" explains Valentini.

That said, eating well - in a balanced and healthy way - is important for everyone, therefore also for people with this condition. "An adequate diet, rich in fruit and vegetables (and therefore in fiber) prevents obesity, and all the complications that can be associated with it, from sleep apnea to diabetes and cardiovascular problems ".

19. Prospects for the future in the therapeutic field

As we have seen, much has been done to improve the expectation and quality of life of people with Down syndrome, with respect to the individual malformations and diseases that can affect them at birth or throughout life.

What is still missing is a therapeutic strategy that can change things also on the front of intellectual disability, preventing it or helping to enhance their cognitive abilities. This is a rather active line of research and, as summarized by a study published in 2022 in the American Journal of Medical Genetics, in various parts of the world several clinical studies are already underway - or will start shortly - precisely to evaluate safety and the possible effectiveness of some molecules with respect to these objectives.

One of the most promising substances in this regard is the bumetanide, a diuretic drug used for more than fifty years and which has come to the fore in Down syndrome studies thanks to the work of the Laura Cancedda, senior researcher at the Del Paeseno Institute of Technology in Genoa and the Telethon Dulbecco Institute. For several years Cancedda and collaborators have been studying the molecular mechanisms underlying Down syndrome in mice, in an attempt to understand how the trisomy of chromosome 21 causes all the problems we know well. In the course of these studies, the researchers discovered a very particular aspect of the functioning of the brains of animals with the syndrome and that is the fact that there is a 'excessive excitation of the synapses, the areas of communication between individual nerve cells.

"Not only that: we also found that, again in mice with the syndrome, the diuretic bumetanide is able to reduce this excessive nervous excitement, and that the animals that receive it show a recovery of cognitive abilities and in particular an improvement in memory "explains the scholar. From here to the idea of ​​trying to experiment the drug also in people with the syndrome it was a short step. Once the necessary authorizations were obtained (which took some time), one Clinical study should start soon at the Bambino Gesù Hospital in the city, with the clinical coordination of Stefano Vicari. "The drug will be administered to a group of adolescents with the syndrome" says Cancedda, who has obtained excellent results in animals precisely with adults.

Other clinical trials on different molecules, ranging from antioxidants to antidepressants, instead concern younger children (newborns or infants), or even pregnant women who know they are expecting a baby with Down syndrome. "The scientific idea behind it is that better results can be obtained on a brain that is still developing," explains Cancedda. "It is an absolutely valid hypothesis, but it is also true that the sooner we intervene, the greater the risk of unforeseen long-term effects, precisely because we intervene on a brain that is still forming".

In short, there are many perspectives - among other things, Cancedda and collaborators are also working on the hypothesis that bumetanide can also help with some sleep disorders of people with Down syndrome - but for the moment there are still certainties. there are none.

20. Down syndrome: which sports to do, which to avoid

Sport is great for children and young people with Down syndrome - including those who have been operated on for congenital heart disease - starting from the fact that it reduces the risk of obesity and related complications. Many find great gratification in sport, and a path of personal fulfillment that can even lead to the victory of Paralympic medals, as in the case of Del Paesena swimmer Nicole Orlando.

"That said, there are some sports that are contraindicated because they can cause trauma to the neck, which is a weak point for people with Down syndrome due to ainstability of the ligament that joins the head to the neck"explains Valentini. No, therefore, to horseback riding if it involves jumps (but yes to hippotherapy), to martial arts (" you can do the training but not the fights "), to head dives from the trampoline:" Very well instead swimming, even synchronized ".

21. The potential and quality of life

"It cannot be denied: the road, for a person with Down syndrome and for his family, is uphill," said Diletta Valentini. "There is a lot to do, but if children with this syndrome are welcomed and cared for in the right way, they can achieve great results in terms of autonomy and self-fulfillment." Not surprisingly, Valentini has a secretary with Down syndrome, Annachiara, who enthusiastically tells the families who arrive at the clinic about her successes: a permanent job, the ability to take the means by herself, the joy of going to vacation with friends.

This "right way" has several components: from acceptance by the family and society to support at school, from adequate stimulation with rehabilitation and various hobbies (painting, music ...) to a path of taking charge health that provides for periodic checks, from the existence of paths on autonomy to that of work placement projects. And everyone (families, institutions, associations) must do their part.

To learn more:

  • March 21, 2022: the contribution of people with Down syndrome to society is celebrated
  • Down syndrome, the testimonies of mothers
  • Advice for parents with children with Down syndrome
  • Down syndrome: 10 commonplaces to say enough is enough
  • Down syndrome: practical guide for families

Updated on 20.03.2022

  • down syndrome
  • genetic diseases
  • newborn 0-3 months
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