Down syndrome, or trisomy 21, is a genetic syndrome that determines a characteristic physical appearance and an intellectual disability of varying degrees (Video). In Italy, it affects about 1 in 1000 children, about 500 every year.
At birth, newborns with Down syndrome may have some characteristic features:
- reduced muscle tone
- eyelid rims oblique upwards and outwards
- small mouth and protruding tongue
- head flattened in the back
- weight and length below average
Although children with Down syndrome share some common physical characteristics, each child is a unique individual and as such can manifest the typical characteristics of the syndrome in a different way.
Down syndrome can be identified during pregnancy through so-called prenatal screening tests.
People who undergo the combined test should be aware that a positive result does not equate to a finding of Down syndrome but only expresses a probability that it may be present. The test result must be interpreted by experts through genetic counseling at following which further investigations may be prescribed In the event that Down's syndrome is confirmed, the geneticist will be able to provide the couple with all the necessary information.
Down syndrome is caused by having an extra chromosome 21: three copies instead of two. For this reason it is also called trisomy 21. In most cases it is not hereditary and derives from an error in the cell division of the egg or sperm.
Numerous investigations have highlighted the relationship between the increased possibility of having a child with Down syndrome and advanced maternal age.
To date, various strategies are available to promote development and the achievement of adequate levels of autonomy:
- access to good health care, including evaluations by various specialists
- adequate support for children and parents
- active role of parents in treatment
- training and support groups that provide information and help to parents, friends and families
In particular, it has been shown that a better knowledge of the syndrome and support for parents have been able to favor the autonomy of people with Down syndrome by promoting life outside the family context, the development of new relationships, "obtaining employment and leading a largely independent life.
It is important to keep in mind that each child is different from the other and, therefore, it is not possible to predict its development possibilities.
People with Down syndrome suffer more frequently than the general population from:
- vision and hearing problems
- heart disease such as, for example, congenital heart disease
- thyroid diseases such as hypothyroidism
- repeated infections
Children with Down's syndrome must undergo pediatric visits more frequently than others to prevent other diseases, if neglected, interfere and limit their development potential. The pediatrician and child neuropsychiatrist, for children, and the family doctor and neurologist, for adults, are the reference figures who will follow its development over time and prescribe the necessary tests. Today, national and international guidelines are available for managing the medical problems of people with Down syndrome.
Children with Down syndrome can be referred by the treating doctors for inclusion in the regional and national registries of rare diseases. These are useful tools for studying strategies to prevent and treat the syndrome. It will however be possible, at any time, request cancellation from the register.
There are Italian and international associations that offer support to families in acquiring information on rights and on projects to develop autonomy. You can find information by visiting the websites or by contacting the associations directly.Symptoms
Although children with Down syndrome may have different characteristics, many share physical aspects and developmental problems.
Some common physical characteristics include:
- small nose and wide nose bridge
- small mouth and protruding tongue
- eyelid rims oblique towards the top
- flattening of the back of the head
- large space between the first and second toes (sandal sign)
- wide hands with short fingers
- single palm fold
- weight and length at birth below that expected for age
Each child can manifest the typical physical characteristics of the syndrome in a different way and can still present both physical and mental aspects that make him resemble the members of his family.
Children with Down's syndrome have developmental difficulties of varying degrees. In the first years of life it is possible to find a delay in reaching the stages of psychomotor development (eg delay in the acquisition of sitting position, walking and the emergence of expressive language).
About 1 in 10 children have some developmental difficulties related to autism spectrum disorders (ASD) or attention deficit hyperactivity disorder (ADHD).
People with Down syndrome may have some disorders more often than normal. Among these: heart and intestinal problems, difficulties in sight and hearing and an increased risk of infections. For this reason, children with Down syndrome must undergo pediatric visits more frequently than other children to prevent these problems. if neglected, they can limit the potential for development.Causes
Down syndrome, or trisomy 21, is caused by having an extra copy of chromosome 21: three copies instead of two. For this reason it is also called trisomy 21.
Normally, cells in the human body contain 46 chromosomes. A child inherits 23 chromosomes from the mother and 23 chromosomes from the father. In people with Down syndrome all or some cells contain 47 chromosomes, as there is an extra copy of chromosome 21. This excess genetic material alters the course of development and causes the typical characteristics of Down syndrome.
Types of Down Syndrome
There are three types of Down syndrome:
- trisomy 21, is the most common type and accounts for approximately 94% of cases. It occurs before conception and consists of an alteration in the sperm or egg cell that results in the presence of an extra copy of chromosome 21. In this condition, all cells in the body have 47 chromosomes
- translocation, it represents about 4% of Down's syndromes and occurs when a translocation is present in the chromosomes (karyotype) of one of the parents; in other words, an extra part of chromosome 21 is "attached" to another chromosome. Parents have a high probability of generating a sperm or egg cell with a supernumerary part of chromosome 21. In this condition, the number of chromosomes in the affected person's cells is 46 but the presence of an additional part of chromosome 21 causes the characteristics of Down syndrome
- mosaicism, accounts for about 2% of Down syndrome cases. This condition occurs after conception and consequently trisomy 21 is not present in all cells of the individual. Thus, only some of the cells have 47 chromosomes.
Probability of Down's Syndrome
In any pregnancy, there is a low probability of having a baby with Down syndrome. Currently, there is no evidence that Down syndrome can be caused by any particular factors or activities performed before or during pregnancy although some people have a higher risk of having a baby with Down syndrome. The advanced age of the mother at the moment of conception is recognized as one of the main risk factors. However, children with Down syndrome are born to mothers of all ages. The probability is also increased if Down syndrome has already been ascertained in a previous pregnancy.Diagnosis
There are two types of prenatal tests for Down syndrome: screening tests and diagnostic tests.
Screening tests can provide an estimate of the risk of the fetus having a "chromosomal abnormality" while diagnostic tests can help make a diagnosis with certainty.
The prenatal period is of fundamental importance for the couple's preparation for the future life of the child to be born. It is recommended that qualified personnel provide comprehensive information on the risks of malformation, genetic pathologies, the possibilities of prenatal diagnosis and the decisional alternatives that can be taken.
Several types of prenatal screening tests can currently be used. These tests can be performed starting in the first trimester of pregnancy and are intended to provide an individual estimate of the risk of trisomy 21.
In the event that the screening test is positive, interpretation of the result should be performed by genetic counseling experts who may require further investigation.
In the first trimester of pregnancy, the combined test may be performed. This test is performed between the eleventh and fourteenth week of pregnancy and includes a maternal blood test and ultrasound measurement of the nuchal translucency (thickness of a space between the skin and the vertebral column behind the nape of the fetus). This prenatal test allows us to estimate the risk of a fetus suffering from Down syndrome at a very early stage. Other less accurate screening tests may be done in the second trimester of pregnancy.
It is important to underline that these tests do not provide certainty but allow to assess the risk even in young women and to limit the use of invasive techniques, reserving them only for cases with increased risk.
Assessment (diagnosis) in pregnancy
The main tests used to ascertain (diagnose) Down syndrome during pregnancy are:
- villocentesis, it can be performed starting from the eleventh week of gestation and consists of the sampling of chorionic villi (a portion of the placenta of fetal origin whose cells, therefore, have the same genetic material as the fetus) by inserting a needle through the maternal abdomen, under ultrasound guidance
- amniocentesis, it can be performed starting from the fifteenth week of gestation and consists in taking a sample of amniotic fluid (the liquid that surrounds the fetus, rich in fetal cells) by inserting a needle, under ultrasound guidance, through the maternal abdomen
- cordocentesis, it can be performed between the eighteenth and twenty-second weeks of gestation and consists in taking fetal blood from the umbilical cord
The benefits and risks of performing these diagnostic tests must be discussed with your doctor.
Assessment (diagnosis) at birth
At birth, the diagnosis of Down syndrome is made on the basis of the physical characteristics of the newborn. The confirmation comes from the study of the chromosome kit by taking a blood sample to determine the possible presence of a supernumerary copy of chromosome 21 in the child's cells.Living with
People with Down syndrome and their families may be confronted with different kinds of difficulties.
The emotional impact
Family acceptance of the diagnosis may be quick or may take longer. Having as much knowledge as possible about the syndrome will allow you to better understand how it may affect your future life.
Thousands of people in Italy have Down syndrome and many parents find it helpful to talk to other people living in the same situation as themselves. Family associations also have among their purposes to put families in contact with each other to share experiences and information on all aspects related to Down syndrome and to offer advice.
Helping children with Down syndrome
Most children have a hard time learning new things and may take longer to reach normal developmental milestones, such as walking and talking.
To help the child in daily life it is useful:
- make him learn through the gameor, for example, show him how to use toys and encourage him to reach for them, grab them and move around
- name and talk about things that interest himanus
- favor its integrationand and sharing experiences with other children
- Promote activities such as eating, dressing-undressing, getting ready for bed, brushing teeth and using the bathroom from an early stage of development
- play games that encourage vocabulary development and word recognitionAnd
It is important to find a balance between the activities carried out within the family and the specialized ones in order to ensure that the child grows up in an environment adapted to his needs. Like all children, he may need to adapt to what is happening around him. him and the needs of other family members Not all activities must necessarily have an educational purpose, fun activities to share with the family are also important and useful.
The development of children with Down syndrome can be fostered by supportive interventions targeted to the needs of each child.
Specialists in pediatrics and child neuropsychiatrists have the task of assessing the specific developmental needs of the child and defining the most appropriate interventions. Support must also be ensured at school and in the family through the involvement of parents in the child's care process.
Regular medical checks
Since some diseases can appear more than normal in people with Down syndrome, periodic medical checks are necessary to identify them and start treatment quickly.
Starting from the first years of life, a lot of attention must be paid to the regular control of growth (evaluated with specific growth curves), of sight, of hearing, of the functioning of the thyroid gland, of the teeth, as well as to a correct diet for prevention. of obesity and tests to detect the onset of heart problems.
A series of protocols are available, diversified according to age, to follow the syndrome over time.
Teenagers with Down syndrome
The care and assistance services for people with Down syndrome are provided by the health service for children up to 18 years of age and by the adult health service thereafter. Between the ages of 16 and 18, people with Down syndrome enter what may be called the 'service transition phase'.
Adult with Down syndrome
The level of education that a person with Down syndrome will reach and the work activity they will be able to carry out are strictly dependent on their personal abilities. With support, many adults with Down syndrome are able to lead an active life to some degree. Although it may not always be possible to live in a state of full autonomy, if adequately supported some adults with Down syndrome move away from the family and live in the community.Complications
People with Down syndrome need to undergo regular clinical checks for the prevention or detection (diagnosis) in the initial (early) phase of the diseases associated with their condition. The main ones include:
Congenital heart disease affects about 50% of people with Down syndrome. For this it is necessary to schedule periodic checks to identify any heart problems to be treated early or the need for surgery.
Intestinal disorders range from constipation, diarrhea, indigestion to more serious diseases such as duodenal stenosis. Some children develop celiac disease and gastroesophageal reflux disease. Even some rare conditions such as Hirschsprung's disease and imperforate anus are more common in people with Down syndrome.
Hearing and vision problems
Visual and hearing disorders, when present, are an important obstacle to the development of any child and are particularly so in people with Down syndrome because they can interfere with the effectiveness of rehabilitation programs for the acquisition of new capacity.
About 80% of people with Down syndrome, of any age, may have a more or less severe hearing defect. In the first year of life, a characteristic serous otitis may appear which may persist over time. Prevention of hearing problems is very important to avoid adding further difficulties to the development of good communication and social skills.
Vision problems are also quite common. These include strabismus, myopia or hyperopia, cataracts (progressive opacification of the lens, the natural lens of the eye), glaucoma (increased intraocular pressure), nystagmus (rhythmic and involuntary movements of the eyes) and keratoconus (disease in which the cornea protrudes forward and assumes a conical shape) as well as eye infections such as conjunctivitis, uveitis or blepharitis.
Compared to the general population, people with Down syndrome have a higher risk of developing changes in the thyroid gland, a gland that produces hormones involved in the physical and mental development of children.
The possibility of hypothyroidism occurring is more common and may be due to the absence of the thyroid at birth (congenital hypothyroidism) or to the attack of the thyroid by the immune system (autoimmune hypothyroidism). One in twelve people with Down syndrome has compensated or clinically manifest hypothyroidism. Clinical symptoms of hypothyroidism (slowness, fatigue, decreased attention) can be confused with other manifestations of the syndrome, especially in adolescence or adulthood, because some neurological or psychiatric disorders become more frequent, regardless of the condition of the thyroid. .
Increased risk of infections
There is a greater sensitivity to infections because the body's defense system (immune system) does not develop fully adequately. In children with Down syndrome, optional vaccinations, including influenza vaccination, are also strongly recommended.
Dementia may appear at a younger age than the general population, typically before age 40. Possible signs that indicate its development include problems with short-term memory, confusion and disorientation.
Recent studies suggest, however, that most adults with Down syndrome age normally even though they probably age earlier than others and may have a lower risk of getting Alzheimer's than previously thought. It is also possible that intensive rehabilitation and social inclusion are effective in slowing the mental deterioration of age.
LGSD Group (Down Syndrome Guidelines), National Center for Rare Diseases (ISS). Multidisciplinary guidelines for integrated care for people with Down syndrome and their families 2007
European Down Syndrome Association (EDSA). Multidisciplinary guidelines for integrated care for people with Down syndrome and their families 2005
National Center for Rare Diseases (CNMR - ISS). Rare Disease Guidelines. Down syndrome