Down syndrome (trisomy 21): what is it, symptoms, treatment, prognosis

What is Down Syndrome?

Down Syndrome, also known as trisomy 21, is a genetic disorder that occurs when a person has a complete or partial extra copy of chromosome 21. The condition is characterized by varying physical characteristics, an increased risk of certain medical problems, and varying degrees of developmental delays and mental retardation.

If you just found out that your child has Down syndrome, you probably have a lot of questions and concerns. You may even be a little intimidated by the way you take care of a child who is likely to have many physical and intellectual problems throughout their lives.

However, since the disorder was first described by a British physician named John Langdon Haydon Down back in 1866, medical researchers have learned a lot about Down syndrome, understanding the wide variety of symptoms and characteristics it causes, have developed treatments and educational programs to help children with disease.

In order for a child with trisomy 21 to reach their full potential, early intervention is key. As a parent, the more you learn about the disorder and the sooner, the better you will prepare your child (and yourself) for successful therapy.

Genetics

Every cell in the human body comes from a single fertilized egg, or zygote, which duplicates itself over and over to create different cells and tissues of the body. To understand Down syndrome, you need to have some basic understanding of chromosomes and genes.

Chromosomes, like the genes located on them, go in pairs. Each chromosome contains genes that provide specific information about the body, from eye color and potential growth to features such as dimples and the risk of developing certain diseases.

What Causes Down Syndrome?

Usually people inherit 23 pairs of chromosomes from both parents, 46 in total. However, people with Down syndrome get 47 chromosomes because they get an extra copy of chromosome 21. This happens when the 21st pair of chromosomes is not separated from either the egg or the sperm.

Down syndrome types

Although the general clinical term for Down syndrome is trisomy 21, the term actually refers to one of three types of chromosome 21 abnormalities. All three types of the disorder are genetic conditions, but only 1 percent of trisomy 21 cases are passed from parent to child through genes.

• Complete trisomy 21: This is the most common chromosomal abnormality seen in children. It accounts for 95 percent of Down's disease cases. The extra chromosome comes from the mother in 88% of cases and from the father in 12% of cases.
• Translocation trisomy 21: It happens when two chromosomes, one of which is number 21, join together at the ends, creating two independent chromosomes of number 21, as well as chromosome number 21 attached to another chromosome. Approximately two-thirds of translocations happen by chance, while the rest are inherited from the parent. Although translocation trisomy 21 occurs by a different mechanism than complete trisomy 21, the physical condition and characteristics that characterize this condition are the same.
• Mosaic trisomy 21: In this rare form of the disorder, which accounts for only 2-3 percent of cases, only a few cells have an extra copy of chromosome 21. People with mosaic Down syndrome may have all of the signs of complete trisomy 21, none, or only a few.

Down syndrome symptoms

Down syndrome is a genetic disorder in which there is an extra complete or partial chromosome 21. For most people with the syndrome, this abnormality causes many distinctive physical signs as well as potential health problems and illnesses. The exception is those patients who have a relatively rare form of the disease, called mosaic trisomy 21, in which not all cells have an extra chromosome 21. A person with this type of trisomy 21 may have all of the features of complete trisomy 21, some or none at all.

Many manifestations total trisomy 21 very noticeable - for example, a round face and slanting eyes with upturned corners (see. photo), as well as a short stocky build. People with the disease sometimes move awkwardly, usually due to low muscle tone (muscle hypotonia) at birth, which can hinder physical development.

Down syndrome is also associated with developmental delays and intellectual disabilities, although it is important to remember that the magnitude of these problems is very different.

Physical signs

The first sign that a child may have Down's disease may appear during normal prenatal screening. On a maternal blood test, called a quadruple screening, elevated levels of certain substances may be a warning sign of Down syndrome, but this does not mean that the child definitely has disorder.

Visible signs.

On ultrasound (images of a developing fetus, also called a sonogram), visible signs that may indicate a child's Down syndrome include:

• excess skin at the back of the neck (occipital opacity / crease);
• very short femur;
• lack of nasal bone.

These signs prompt healthcare providers to perform amniocentesis or chorionic villus sampling, both prenatal studies that examine cells taken from the amniotic fluid or placenta, respectively, and can confirm the diagnosis disorders. Some parents agree to this research, while others refuse.

Features of people with Down syndrome

People with trisomy 21 have many facial and body abnormalities. They are most obvious at birth and may become more pronounced over time. The obvious symptoms of Down syndrome include:

• Round face with a flat profile and small nose and mouth;
• A large tongue that may protrude from the mouth
• Almond-shaped eyes with the skin that covers the inner eye (epicanthus);
• White specks in the colored part of the eyes (Brushwild spots);
• Small ears;
• A small head that is slightly flat at the back (brachycephaly)
• Short neck;
• Clinodactyly: One fold in the palm of each hand (usually two), short bristly fingers and a little finger curving inward;
• Small feet with more space than usual between the big and second toes;
• Short, stocky build: At birth, babies with Down's disease are on average of normal size, but tend to grow more slowly and remain smaller than other babies of their age. People with trisomy 21 are also often overweight;
• Low muscle tone: Children with trisomy 21 often appear "lethargic" due to a condition called muscle hypotonia. Although hypotension can and often improves with age and physical therapy, most children with the disorder tend to develop - sitting, crawling, and walking - later than other children. Low muscle tone can contribute to nutritional problems and motor delays. Toddlers and older children may have delays in speaking and learning skills such as feeding, dressing, and potty training.

Intelligence and development

All people with the disease have some degree of mental retardation or developmental delay, which means they tend to learn slowly and can struggle with complex reasoning and judgment.

There is a common misconception that children with Down syndrome have predetermined limitations in their ability to learn, but this is completely wrong. It is impossible to predict the extent to which a child born with Down's disease will be intellectually disadvantaged.

According to an international organization helping people with Down syndromeThe related problems can be explained as follows:

• Slow development of motor skills. Delays in reaching milestones that allow a child to move, walk, and use their hands and mouth can reduce it opportunities to explore and experience the world, which, in turn, can affect cognitive development and the development of language skills.
• Expressive language, grammar and speech clarity. Due to delays in the development of language comprehension, most children with Down syndrome are slow to master the correct sentence structure and grammar. In addition, they are more likely to have trouble speaking clearly, even if they know exactly what they are trying to say. This can cause frustration and sometimes behavioral problems in the child. It can even lead to underestimation of the child's cognitive abilities.
• Numerical skills. For most children with trisomy 21, numeric skills are more difficult to master than reading skills. In fact, the former tends to lag behind the latter by about two years.
• Verbal short-term memory. Short-term memory is a system of random access memory that uses the information just learned for short periods of time. It supports all educational and cognitive activities and has separate components for processing visual or oral information. Children with the disorder poorly store and process information that comes to them orally, as they remember what appears to them visually. This can place them at a particularly disadvantageous position in classrooms, where much of the new information is taught by speech.

It is clear that people with trisomy 21 have the potential for lifelong learning and that their potential can be maximized. increased through early intervention, good education, high expectations and encouragement from family, caregivers, and teachers. Children with this disorder can learn and develop skills throughout their lives. They just take longer to reach their goals.

Psychological signs

People with Down syndrome are often perceived to be particularly happy, outgoing, and warm people. While this may generally be true, it is important not to stereotype them, even when it comes to labeling them with such positive qualities.

People with this disorder experience a full range of emotions and have their own characteristics, strengths, weaknesses, and styles - just like everyone else.

There are some behaviors associated with this disorder that are largely related to the unique problems that cause the condition. For example, most people with Down syndrome tend to need order and routine when dealing with the complexities of daily life. They strive for routine and often insist on the same type. This can be interpreted as innate stubbornness, but this is rare.

Another behavior commonly seen in people with Down's disease is talking to oneself - something that everyone does sometimes. It is believed that people with trisomy 21 talk to themselves to process information and make sense of a decision.

Complications

As you can see, it is difficult to separate some of the features of Down syndrome from its potential complications. Keep in mind, however, that while many of the above issues are undeniable concerns, others are simply pointing the way for the person who is outside the "norm." People with Down's disease and their families take it differently.

However, people with the disorder are more likely than other healthy people to have certain physical and mental health problems. Lifelong caring can be compounded by the following additional challenges.

Hearing loss and ear infections.

According to the National Institutes of Health, up to 75 percent of children with the condition have some form of deafness. In many cases, this can be due to abnormalities in the bones of the inner ear.

It is important to identify hearing problems as early as possible, as hearing impairment can cause speech and language delays.

Children with trisomy 21 are also at increased risk of ear infections. Chronic ear infections can contribute to hearing loss.

Vision or eye health problems.

According to some reports, 60 percent of children with a disorder have vision problems such as myopia, hyperopia, strabismus, cataract or a blockage in your tear ducts. Half of the patients will need to wear glasses.

Infections.

The National Institutes of Health states, "Down syndrome often causes problems in the immune system that can prevent the body from fighting infections." Babies with this condition are 62% more likely to get sick pneumonia in the first year of life than, for example, other newborns.

Problems with the musculoskeletal system.

The American Academy of Orthopedic Surgeons lists a number of problems affecting the muscles, bones, and joints of people with Down syndrome. One of the most common is an upper neck anomaly called atlantoaxial instability, in which the vertebrae in the neck become dislocated. It does not always cause problems, but when this pathology occurs, it can lead to neurological symptoms such as clumsiness, difficulty walking or abnormal gait (such as lameness), nerve pain in the neck and muscle tension, or reductions. Down syndrome is also associated with joint instability, leading to dislocation of the hips and knees.

Heart defects.

About half of all children with trisomy 21 are born with heart defects. These can range from mild problems that may improve over time to serious defects that will require drug therapy or surgery.

The most common heart defect seen in children with the syndrome is atrioventricular septal defect - holes in the heart that interfere with normal blood flow. The problem may require surgical treatment.

Children with Down syndrome who were born without heart problems should also not have them later in life.

Gastrointestinal problems.

People with Down syndrome tend to be at increased risk of various gastrointestinal problems. One of the conditions called duodenal atresia, is a deformation of a small tubular structure (duodenum) that allows digested material from the stomach to pass into the small intestine. In the newborn, this condition causes bloating in the upper abdomen, excessive vomiting, and lack of urination and bowel movements (after the first few meconium bowel movements). Duodenal atresia can be successfully treated with surgery shortly after birth.

Other gastrointestinal disease with disorder - Hirschsprung's disease - lack of nerves in the colon, - causing constipation. Celiac disease, which causes gut problems when a person eats gluten, a protein found in wheat, barley, and rye that is more common in people with Down syndrome.

Hypothyroidism

In this condition, the thyroid gland produces little or no thyroid hormone that regulates body functions such as temperature and energy. Hypothyroidism may be present at birth or develop later in life, therefore, this condition should be checked regularly, starting with the birth of a child with Down's disease.

Disorders of the blood.

These include anemiain which red blood cells do not have enough iron to carry oxygen to the body, and polycythemia (the level of red blood cells is above normal). Children leukemia, a type of cancer that affects white blood cells, occurs in 2-3% of children with Down syndrome.

Epilepsy.

According to the Department of Health, this seizure disorder most often occurs during the first two years of a person with Down syndrome or develops after the third decade.

About half of people with the disorder develop epilepsy after 50 years.

Mental health disorders.

Higher rates have been reported in Down syndrome anxiety disorders, depression and obsessive compulsive disorder. The good news is that these psychological problems can be successfully treated with psychotherapy and medication.

Also, people with this disorder are more at risk of getting sick than others. Alzheimer's disease.

Down syndrome causes

Down syndrome occurs when an extra copy of chromosome 21 (or part of it) appears in a person's genetic code. It is not always clear why this anomaly occurs. In most cases, it occurs by accident when sperm fertilizes an egg, it can also cause certain risk factors, and one type of disorder that can be transmitted by inheritance.

Trisomy (i.e. the presence of three homologous chromosomes instead of a pair (normal)) for a specific chromosome, including number for chromosome 21, is the result of improper division of sperm or egg up to conception. Each of the three types of trisomy 21 has slight differences in terms of how they are triggered:

• Complete trisomy 21: Chromosomes line up to divide and create eggs or sperm in a process called meiosis (reduction division). With this type of Down syndrome, division does not occur. Those. the egg has not one, but two 21st chromosomes. After fertilization, this egg receives a total of three chromosomes. This is the most common way the syndrome occurs.
• Translocation trisomy 21: During translocation, there are two copies of chromosome 21, while additional material is attached (translocated) to the third chromosome 21. This type of trisomy 21 can occur both before and after conception and is a form that can sometimes be inherited.
• Mosaic trisomy 21: This is the least common form of trisomy 21. It occurs after conception for unknown reasons and differs from the other two types of trisomy 21 in that only a few cells have an extra copy of chromosome 21. For this reason, the symptoms of a person with mosaic trisomy 21 are not as predictable as in complete and translocation trisomy 21. They may seem less obvious depending on which cells and how many cells have a third chromosome 21.

Genetics

Only one type of Down syndrome - translocation — considered hereditary. This type is very rare. It is believed that only a third of people inherit a translocation.

A translocation that will ultimately lead to the child developing Down's disease often occurs when a child is conceived. Part of one chromosome breaks down and joins another chromosome during cell division. This process produces three copies of chromosome 21, with one copy attached to another chromosome, often chromosome 14.

This abnormality does not affect the normal development and function of the parents, as all the genetic material required for chromosome 21 is present. This is called balanced translocation. However, when someone with a balanced translocation has a baby, there is a chance that it will lead to the fact that this child will have an extra chromosome 21 and, therefore, he will be diagnosed with the syndrome Down.

There is an increased likelihood that the parents of a child with Down syndrome due to translocation will have other children with the disorder. It is also important that the parents of a child with a translocation know that their other children may be carriers and may be at risk of having a child with trisomy 21 in the future.

If a woman with Down's disease becomes pregnant, she has an increased risk of giving birth to both a sick child and a healthy one.

According to most published data, between 15% and 30% of women with Down syndrome are able to become pregnant, and the risk of having a child with the disease is approximately 50%.

Risk factors

There are no environmental factors, such as toxins or carcinogens, that could cause disorders, as well as lifestyle (such as alcohol, tobacco or drug use). The only known non-genetic risk factor for having a baby with Down syndrome is what is sometimes called elderly maternal age (over 35 years old).

However, this does not mean that having a baby before the age of 35 is a reliable strategy for the prevention of Down syndrome. Approximately 80% of children with trisomy 21 are born to women younger than 35 years old.

Here's how the risk of the disorder increases with the age of the mother:

Age	Risk
25	251 of 1200
30	1 in 900
35	1 in 350
40	1 in 100
45	1 in 30
49	1 out of 10

Diagnostics

Down syndrome in an infant can be diagnosed at birth or shortly after birth based on certain physical characteristics, such as being smaller than usual, head, eyes shifted upward, a small mouth with a protruding tongue and one fold (rather than two) across the palms, as well as a large space between the large and the second toes.

Babies with Down syndrome are also prone to lethargy, which means they have muscle hypotonia. And some are born with serious health problems, such as heart disease and the gastrointestinal tract.

To confirm that a child with these characteristics has a disease, a chromosome analysis called karyotypingusing a child's blood sample.

However, research today is conducted in such a way that Down syndrome can also be detected (or at least suspected) even before the birth of a child. In number prenatal examinations and analyzesthat can help predict the birth of a baby with Down syndrome include:

• Ultrasound procedure: Also called a sonogram, this imaging test of a developing fetus sometimes reveals subtle physical signs that indicate an increased risk of the syndrome.
• Maternal serum screening: a blood test of the expectant mother between the 13th and 28th weeks of pregnancy, four times screening suggests that the fetus is at risk of developing trisomy 21. However, this study does not provide an accurate diagnosis.
• Amniocentesis: this test involves using a sample of amniotic fluid for karyotyping. If the extra number 21 is present, the syndrome is diagnosed. Amniocentesis is done between 15 and 20 weeks.
• Chorionic villus sampling: as in the case of amniocentesis, the study uses karyotyping. However, the cells examined are taken from the placenta and not from the amniotic sac. Chorionic villus sampling is performed at 9-11 weeks of gestation.

Down syndrome treatment

Down syndrome (trisomy 21) is not a disease or condition that can be permanently corrected with medication or surgery. Therefore, the goal of treatment is not to cure the disease itself, but to address a range of health problems, diseases, as well as physical and intellectual problems that people with Down's disease may face throughout own life. The options for such therapy can be very diverse - from physical therapy and early intervention to aids, medications, and even surgery.

Treatment methods

Most children with the syndrome require different types of therapy. Some focus on helping patients achieve physical milestones at the same speed as those without the disorder. Others aim to help them become as independent as possible when they come of age.

Early intervention.

The sooner children with a medical condition receive the personalized care and attention they need to cope with their specific health and developmental problems, the more likely they are to achieve their full potential.

Early intervention is a systematic program of therapy, exercise and intervention aimed at elimination of developmental delays that children with Down syndrome or other disabilities may experience opportunities. Early intervention typically includes the following three types of therapy:

• Physiotherapy. Most children with the disorder develop hypotonia (weakness in the muscles), which can slow their physical development and, if left untreated, lead to future posture problems. Physical therapy can help develop muscle tone and strength, as well as teach you how to properly move your body, helping with everyday life.
• Speech therapy. Children with Down syndrome often have small mouths and slightly dilated tongues - features that make it difficult for them to speak clearly. These problems can be exacerbated in children with hypotension because low muscle tone can affect the face. Hearing loss can also affect the development of speech. Through speech therapy, the child with the disorder can learn to overcome these obstacles and speak more clearly. Some children also benefit from learning and using sign language.
• Occupational therapy. This type of therapy helps children develop the skills they need to be as independent as possible. Occupational therapy includes a variety of activities ranging from teaching how to lift and release objects, turn knobs, press buttons, ending with self-feeding and dressing.

The goal of this multifaceted approach to Down syndrome treatment is to help people with the disorder successfully make the transition to a more independent adult life.

Assistive devices

Thanks to advances in technology, there is an ever-growing range of products that can help people with Down syndrome more easily and more successfully cope with their individual challenges. Something like hearing aids and glasses are the same devices that are useful for people who do not have Down syndrome, but sharing certain concerns that are common among people with trisomy 21, such as hearing loss and problems with vision.

In addition, there are all kinds of assistive devices that are especially useful for teaching. They range from simple objects such as triangular pencils and easy-to-handle spring-loaded scissors, to more complex devices such as touchscreen computers or keyboards with large letters.

As with all Down syndrome treatments, which aids will be most helpful child with this disorder will depend on the degree and type of his physical, mental and intellectual deviations. Your child's physical therapist, occupational therapist, social worker, and school teacher will likely know which options are most helpful and how to get them if they are not available to you.

Medications

Many of the health problems that affect a person with Down syndrome can be resolved with medication - usually the same medications given to a person without Down syndrome.

For example, according to the Association Down Syndrome (ADS), about 10 percent of people with this disorder are born with thyroid problems or become ill at a later age. The most common of these is hypothyroidism, in which the thyroid gland does not produce enough of a hormone called thyroxine. People with hypothyroidism - with or without a diagnosis of Down syndrome - usually take a synthetic form of the hormone (levothyroxine) orally to treat the condition.

Because trisomy 21 can cause many diseases at once, many of those who have it also have several different doctors and specialists. ADS refers to this potential problem, noting that "medicines for one person are usually prescribed by several doctors, while not contacting each other at all." It is important to be proactive in managing the drug list so that both prescription and over-the-counter drugs are up to date, dosage and frequency.

In simple terms, if you are a parent of a child with Down syndrome, you should take responsibility for ensuring that your child's various doctors knew about all the prescription and over-the-counter drugs and supplements they regularly take to help prevent dangerous interactions between them.

Surgical intervention

Down syndrome is also associated with certain health problems that may require surgery. It would be impossible to list all the potential aspects, since the medical problems caused by Down's disease vary greatly, but these are some of the most common problems:

Heart defects.

Some congenital heart defects are common in children with Down syndrome. One of them is atrioventricular septal defect (AVSD)in which a hole in the heart interferes with normal blood flow. HDVP is treated with surgery, sealing the opening and, if necessary, correcting any valves in the heart that may not close completely.

Gastrointestinal problems.

Some babies with trisomy 21 are born with a deformity of the duodenum (the tube that allows digested food to pass from the stomach into the small intestine) called duodenal atresia. It requires surgery, but is not considered an emergency if there are other, more pressing medical problems.

Duodenal atresia can be temporarily relieved with a tube placed to relieve swelling in the stomach, and intravenous fluids to treat dehydration and electrolyte imbalances that often result from this states.

Prognosis for people with Down syndrome

Although the prognosis (expected result) for children with Down syndrome depends on the severity of the medical problem and the complications that arise, it has improved over the years. In 1910, the life expectancy of a child born with this condition was 9 years. Today, thanks to improved medical technology and early intervention, 80 percent of people with Down syndrome live to be 55, and many live even longer.

Over time, the quality of life has also improved in many children with the disorder. Typically, children with trisomy 21 can attend school. The question of whether the child will attend regular school or special educational institution, often depends on his skills.

As adults, people with the disorder can live with their families. They can work in offices, nursing homes, hotels, restaurants and other places of work, can get married and have children.

Down syndrome prevention

Some couples pass genetic counseling before getting pregnant to discuss your risk of developing Down syndrome, but ultimately the condition cannot be prevented. Some studies state that women who give birth to a child with the disorder have folate deficiency problems, but this has not been confirmed.