Diagnosis: Down syndrome

Down syndrome (trisomy 21) is the most common genetic disorder in Slovakia. It is caused by an extra copy of chromosome 21 (trisomy), which most often arises due to incorrect cell division. The extra chromosome is responsible for the child’s typical physical features and varying degrees of intellectual disability. In Slovakia, approximately 45 children with Down syndrome are born each year.

Risk factors for developing Down syndrome include:
Advanced maternal age (see table below), and
Errors in recombination – a proven association exists between recombination errors and nondisjunction (faulty cell division).

External risk factors may include smoking, alcohol, coffee, drugs, hormonal medications, spermicides, and radiation. However, despite extensive research across multiple countries and regions, no clear evidence has confirmed a direct influence of internal or external factors on nondisjunction. To date, the only established risk factor for trisomy 21 remains maternal age. Other factors either do not play a role or their impact is negligible compared to the age effect.

Maternal age Risk of Down syndrome
18–30 1 : 1500
35+ 1 : 380
40+ 1 : 110
45+ 1 : 30

Diagnosis:

The cause of Down syndrome is an extra copy of chromosome 21, the smallest human chromosome. Each cell contains 23 pairs of chromosomes. Due to an abnormal change in the genetic information carried by this chromosome, an additional chromosome 21 is formed. The development of cytogenetics and improvements in chromosome‑identification methods in the 1970s made it possible to classify Down syndrome into three groups. The most common type is free trisomy 21, occurring in 88% to 95% of cases, followed by mosaicism in 1% to 7.7% of cases, and translocation trisomy in 4.3% of cases.

Free Trisomy 21: Just before fertilization, cell division occurs. During this division, an incorrect transfer of chromosome 21 can happen. When the pair of chromosome 21 fails to separate for unknown reasons during the first meiotic division and remains joined (a faulty division called nondisjunction), the fertilized egg ends up with not 46 but 47 chromosomes. This nondisjunction is responsible for 93–94% of Down syndrome cases and is referred to as free trisomy 21. The underlying cause of this type of trisomy is still unknown.

Translocation Form: In a small percentage of people with Down syndrome, the extra genetic material from chromosome 21 is not free, but attached to another chromosome (most commonly chromosome 14). In about 1% of cases, one of the parents is a carrier of this translocation without displaying any signs of Down syndrome.

Mosaic Form: In this form, the altered cell division occurs after the fusion of the reproductive cells that each contain a normal number of chromosomes, i.e., during the subsequent (second) intensive divisions of the newly formed cell. As a result of this form, individuals with DS have a certain percentage of cells with a normal number of chromosomes (46), while in other cells there is an extra chromosome 21 (47 chromosomes). These are individuals with the lowest degree of intellectual disability within the Down syndrome spectrum.

Prenatal genetic diagnostics

In Slovakia, biochemical screening tests (blood tests) are performed in the first and second trimesters of pregnancy. These tests are routinely offered to every pregnant woman and determine the probability that the fetus is affected by Down syndrome (or another genetic disorder). The risk of fetal impairment is assessed based on maternal age and biochemical parameter values. Between the 10th and 12th week of pregnancy, an ultrasound examination is performed to measure nuchal translucency (NT). This measurement evaluates the width of accumulated fluid at the back of the fetal neck (an increased width is one of the signs of Down syndrome). If the probability indicated by the screening is higher, amniocentesis (amniotic fluid sampling) is recommended. However, this is an invasive procedure with potential risks, such as damage to the fetal membranes, intrauterine infection, and miscarriage. During this procedure, the genetic code of the baby’s stem cells (present in the amniotic fluid) is analyzed. Another option is the trisomy test, which is non‑invasive yet highly reliable (99%). It analyzes the mother’s blood and determines the risk of Down syndrome as well as the two other most common trisomies based on the DNA of the fetus.

Newborn diagnostics (Postnatal diagnostics)

Immediately after birth, the clinical diagnosis of a child with Down syndrome can be established based on the phenotypic (external) characteristics of trisomy 21. The most frequent signs include slanted palpebral fissures, excess neck skin fold, a flat facial appearance, joint hyperflexibility, hypotonia, and absence of the Moro reflex. Most infants have a smaller head circumference and lower birth weight.

The head of a newborn with Down syndrome is slightly smaller compared to other infants; flattening of the back of the head is more common, resulting in a shorter front‑to‑back diameter (brachycephaly). Newborns with Down syndrome have an enlarged anterior fontanelle and an open posterior (false) fontanelle. The open posterior fontanelle at the back of the head (occipital region of the skull) is considered the most suitable indicator for suspicion of trisomy 21.

The shape and position of the palpebral fissures are typical for individuals with Down syndrome. They are narrow and slanted, with an additional epicanthal fold (Epicanthus) at the inner corner of the eye.

The eyes may show white or slightly yellowish spots along the edges of the iris (Brushfield spots). These gradually disappear as the iris becomes more pigmented. They are also common in the general population of children.

The lips of a baby with Down syndrome are well-shaped; the mouth is often open because the oral cavity is smaller compared to other infants, while the tongue is relatively large in proportion to the oral cavity. Therefore, newborns frequently protrude their tongue.

Hands: About 50% of children with Down syndrome have a single transverse palmar crease. The little finger may be curved toward the other fingers (clinodactyly) and may even have a single joint instead of two. Clinodactyly can also occur in the general population without any link to Down syndrome.

Feet: Toes are shorter, and the gap between the big toe and the other toes is wider.

Based on the typical external features, determining the diagnosis immediately after birth should not pose a problem for any pediatrician. Uncertainty may arise only in cases of partial trisomy 21 or mosaic form, since these forms display fewer typical features compared to free trisomy.

A definitive confirmation of the diagnosis can only be made through cytogenetic testing. No child with Down syndrome shows all possible features; their frequency varies even within the different trisomic forms. Additionally, some physiognomic features typical for Down syndrome can appear in children from the general population, without indicating the diagnosis, without transmitting it, and without the child being affected in any way.

Newborns with Down syndrome

In newborns with Down syndrome, a relatively large number of congenital anomalies may be observed. Some of them are life‑threatening and require immediate intervention after birth, while others appear within several days or weeks.

Most common anomalies:

congenital cataract – 3% of children
congenital anomalies of the digestive tract – 5–12% of children
congenital heart defects – 40–50% of children

It is very important that congenital cataract is diagnosed immediately after birth and extracted without delay; otherwise, the child is at risk of retinal damage and subsequent blindness. Removal of the cataract is a relatively simple surgical procedure and does not endanger the child. Subsequent correction with glasses or contact lenses helps improve the child’s vision.

Among the most common congenital defects of the digestive tract are tracheoesophageal fistula (a connection between the trachea and the esophagus), pyloric stenosis (narrowing of the upper part of the stomach), duodenal atresia (blockage of the upper part of the small intestine), anal atresia (blockage of the rectal opening), and Hirschsprung’s disease (absence of nerve cells in a segment of the large intestine). All of these conditions require urgent surgical intervention. In addition, constipation caused by hypotonia of the abdominal wall is also common.

The most common congenital heart defect is complete atrioventricular septal defect (a hole between the ventricles combined with abnormal structure of the heart valves), incomplete atrioventricular septal defect, ventricular septal defect, atrial septal defect, combined shunt defects, Tetralogy of Fallot, and patent ductus arteriosus.

Most common health problems in children with Down syndrome are associated with:

inadequate nutrition and feeding difficulties due to other health problems, such as congenital heart defects, digestive tract anomalies, and failure to thrive for various other reasons
frequent respiratory infections associated with changes in the immune system
visual impairment (a tendency toward myopia, strabismus, and hyperopia)
hearing impairment (the narrow Eustachian tube canal tends to become blocked by earwax, which may lead to hearing loss if untreated)
seizure episodes
orthopedic problems (presence of abnormal collagen)
sleep‑related breathing disorders (so‑called “sleep apnea”)
dental problems

Life of a child:

Children with Down syndrome are born with positive qualities such as the ability to love, a sense of belonging, tolerance and empathy, spontaneity, and warmth. Without hesitation, they use words like “I love you,” “I like you,” and “I care about you.” Bringing joy to others and sharing in the happiness and successes of others is natural for them.

But like all other children, they also have both better and worse qualities. The same applies to them as to any other children. They are different from one another and have various interests and abilities. They love music, dance, rhythm, painting, and different household activities. When they become enthusiastic about something, they are capable of devoting themselves to it intensely and persistently. All children with Down syndrome have their own limits, which parents and educators should be aware of.

With good upbringing and appropriate guidance, their behavior is normal and they can be an example to other children. Despite general differences in personality, they share some common character traits. They are friendly, kind‑hearted, spontaneous, and open. Among negative traits, stubbornness is typical.

With proper guidance, they are persistent (in a positive sense) and orderly. They endure pain and discomfort very bravely. If they are irritable, distressed, or tearful, there is always an objective cause that should be looked for. Especially children who have additional medical conditions, such as celiac disease or other digestive problems, may sometimes behave inappropriately due to their difficulties, but even this is very individual.

In raising a child with Down syndrome, it is helpful to make use of their special ability - imitation. If they have the opportunity to imitate positive examples, it will be for their benefit. If the behavior they observe in people around them is negative, they will adopt it, and their acceptance in society will become more difficult.

The behavior of children with Down syndrome is influenced not only by their personality but mainly by their upbringing and health condition. A positive influence on the child’s development and personality formation comes from consistent upbringing without excessive overprotectiveness from parents and without any form of manipulation of the child.

Life of an adult individual:

The transformation of society, greater access to information, and increased “openness to the world” are changing not only how people with Down syndrome are perceived, but also how their limits are understood. While in the past they were labeled and considered “eternal children,” today they are encouraged toward independence, the exercise of their civil rights, and many of them grow into relatively self‑sufficient individuals.

During adolescence, the characteristics of each person with Down syndrome become more defined. They differ in their interests, moods, and desires. Much depends on the way they were raised, their education, and the environment in which they live. An overly protective approach by parents may lead to them becoming less independent, more easily influenced, and less tolerant. In some people with Down syndrome, childlike behaviors persist even in adulthood, while others behave like other adults. Despite differences in upbringing, most adults with Down syndrome share traits such as naturalness, sincerity, pride, bravery, sensitivity, and solidarity.

Some possess an interesting but challenging ability in terms of coexistence - the ability to pretend. They may pretend difficulties or illnesses. With their acting skills and talent for imitation, they are capable of confusing even specialists. This tendency can be used positively in theatre groups, dance performances, and gymnastics activities, which many of these individuals continue to enjoy into adulthood.

If they were not guided in childhood, adults with Down syndrome also need to be taught to be more independent, to know how to advocate for themselves, and to understand social norms (etiquette). The more independent, self‑reliant, and responsible they become, the sooner they will be able to speak for themselves, express what they need and what they dislike, and make their own decisions. This will make their integration into everyday social life easier. Teaching them responsibility for themselves, for their own lives, and for their actions is important for their broader acceptance in society.

Myths:

they are unadaptable and aggressive
they are unable to learn
they are uneducable
they must grow up in institutional care
they are objects of charity
they are asexual
they are excessively sexually oriented
they are "patients"
experts make decisions for them
they have many deficiencies
they are dependent and unable to work
they require constant support from society in the form of financial subsidies
they need segregated education, employment, and other areas of life

Reality:

they have excellent ability to imitate and learn
they learn more slowly
all of them are educable
they should grow up in a home environment
they make decisions for themselves
they have the same sexual needs and feelings as other people, some less, some more
they have the right to barrier removal
based on their individual abilities, they can be employed
they need individual and stable support in the areas of education, employment, and compensation
they need to be included in mainstream education and employment

Down syndrome

General