Symptoms of Down Syndrome

Down syndrome (trisomy 21) is a genetic disorder that affects about one in 700 newborns. People with Down syndrome typically have distinctive physical features and intellectual challenges as a result of having an extra chromosome.

A chromosome is a thread-like structure made up of protein and DNA. Humans have 23 pairs of chromosomes inherited from their parents. With Down syndrome, there is an extra full or partial chromosome 21. With the mosaic Down syndrome type, the extra chromosome may not be in all cells, leading to variations in how that's expressed.

This article explains Down syndrome and how it is diagnosed. It discusses Down syndrome's causes, the physical and cognitive effects of the disorder, and what it means for people living with it.

Signs of Down Syndrome

Down syndrome is often easily recognized by features including a round face and upturned eyes, and a short, stocky build. People with Down syndrome sometimes move awkwardly, usually due to low muscle tone (hypotonia) at birth that can interfere with physical development.

Technically speaking, parents and healthcare providers look for signs of Down syndrome, rather than symptoms. These may be seen once a child is born or, in some cases, in utero.

The first indication of Down syndrome can appear during routine prenatal testing. In a blood test called the quadruple screen, elevated levels of certain substances can be a red flag for Down syndrome but are not used to make a definitive diagnosis.

An amniocentesis or chorionic villi sampling (CVS) may be recommended. These prenatal tests are used to examine cells taken from the amniotic fluid or the placenta, respectively. They can confirm a diagnosis of Down syndrome. Some parents opt for these tests, while others do not.

Down Syndrome Features

People with Down syndrome share a host of recognizable facial and physical features. These are most apparent at birth and can become more pronounced with time.

The more obvious characteristics of Down syndrome include:

• A round face, with a flat profile and small nose and mouth
• A large tongue that may protrude from the mouth
• Almond-shaped eyes with skin that covers the inner eye (epicanthus folds)
• White flecks in the colored part of the eyes (Brushfield spots)
• Small ears
• A small head that's somewhat flat in the back (brachycephaly)
• Short neck
• Clinodactyly: A single crease across the palm of each hand (normally there are two), short stubby fingers, and a pinky finger that curves inward
• Small feet with a larger than normal space between the big and second toes
• Short, stocky build: At birth, children with Down syndrome usually are average size, but tend to grow at a slower rate and remain smaller than other kids their age. It's also common for people with Down syndrome to be overweight.

Hypotonia often causes babies with Down syndrome to appear “floppy.” The poor muscle tone can and often does improve with age and physical therapy. Still, most children with Down syndrome typically reach developmental milestones—sitting up, crawling, and walking—later than other kids.

Low muscle tone may contribute to feeding problems and motor delays. Toddlers and older kids may have delays in speech, and learning skills such as feeding, dressing, and toilet training.

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Intellect and Development

All people with Down syndrome have some degree of intellectual disability or developmental delay, which means they tend to learn slowly and may struggle with complex reasoning and judgment.

Some of these challenges include:

• Slow development of motor skills: Delays in reaching milestones that allow a child to move about, walk, and use their hands and mouth can lower their opportunities to explore and learn about the world. This can affect cognitive and language skill development.
• Expressive language, grammar, and speech clarity: Most children with Down syndrome are slow to master sentence structure and grammar, due to delayed language comprehension. They know what they want to say but have trouble speaking clearly, which leads to frustration and, sometimes, behavior problems. It also means their cognitive abilities can be underestimated.
• Number skills: Most children with Down syndrome find it harder to master number skills than reading skills. In fact, a grasp of numbers is typically about two years behind reading.

Kids who have Down syndrome aren't as able to hold and process information that's stored in verbal short-term memory. It's an immediate memory system for just-learned information. But it supports all learning and cognitive activity with visual or verbal information processing, and those with Down syndrome tend to do better with visual information.

This can put them at a special disadvantage in classrooms where most new info is taught through spoken language. Yet people with Down syndrome have the potential to learn across a lifetime, and it can be maximized through early intervention, good education, high expectations, and encouragement from family, caregivers, and teachers.

Children with Down syndrome can and do learn, and are capable of developing skills throughout their lives. They simply reach goals at a different pace.

Down Syndrome Behaviors

Down syndrome is often associated with people who are particularly happy, sociable, and outgoing. This may be true in general, but it's important to avoid stereotypes, even with such positive characteristics and impressions.

People with Down syndrome experience a full range of emotions and have their own strengths, weaknesses, and styles—just like anyone else.

Some behaviors associated with Down syndrome are largely due to its unique challenges. For example, most people with Down syndrome thrive on routine and insist on sameness when dealing with the complexities of daily life. This can be interpreted as innate stubbornness, but that's rarely happening.

People with Down syndrome also engage in a lot of self-talk, which everyone does sometimes. It's thought that self-talk is a way for people with Down syndrome to process information and think things through.

Complications of Down Syndrome

People with Down syndrome are more likely than otherwise healthy people to have certain physical and mental health issues. Care throughout one's life can be complicated by these conditions, some of which are quite common in people living with the disorder.

Hearing Loss and Ear Infections

Many people with Down syndrome have abnormalities in the bones of the inner ear, and up to 75% of children will have some form of hearing loss. They're also at an increased risk of chronic ear infections that can contribute to hearing loss.

It's important to detect hearing problems as early as possible, since being unable to hear well can be a factor in speech and language delays. 

Problems with Vision or Eye Health

As many as 60% of children with Down syndrome will have some type of vision problem. These problems include:

• Nearsightedness 
• Farsightedness
• Crossed eyes
• Cataracts
• Blocked tear ducts

About half of all people living with Down syndrome will need to have their vision corrected.

Infections

Down syndrome often causes problems in the immune system that can make it difficult for the body to fight off infections. For example, infants with the disorder have a 62% higher rate of pneumonia in the first year of life than do other new babies.

Musculoskeletal Problems

Down syndrome leads to common issues affecting muscles, bones, and joints. A condition called atlantoaxial instability (AAI) affects the upper neck when vertebrae in the cervical spine become misaligned.

This condition doesn't always cause symptoms, but when it does a person with Down syndrome may exhibit:

• Clumsiness
• Difficulty walking or an abnormal gait (e.g. limping)
• Nerve pain in the neck
• Muscle tightness or contractions

Down syndrome also is associated with joint instability, leading to hips and knees that may easily become dislocated.

Heart Defects

About half of all babies with Down syndrome are born with heart defects. These can range from mild problems, which may correct themselves over time, to serious defects that will require medication or surgeries.

The most common heart defect seen in infants with Down syndrome is an atrioventricular septal defect (AVSD)—holes in the heart that interfere with the normal flow of blood. An AVSD may need to be surgically treated.

Children with Down syndrome who aren't born with heart problems will not develop them later in life.

Gastrointestinal Issues

Down syndrome often leads to an increased risk for a variety of GI problems. One condition is called duodenal atresia, a deformity of the small tube-like structure (the duodenum) that allows digested material from the stomach to pass into the small bowel.

In a newborn, this condition can cause:

• A swollen upper abdomen
• Excessive vomiting
• Lack of urination and bowel movements (after the first few meconium stools)

Duodenal atresia can be successfully treated with surgery soon after birth.

Another gastrointestinal condition of note in Down syndrome is Hirschsprung disease—an absence of nerves in the colon, which can cause constipation.

Celiac disease, in which intestinal problems develop when someone eats gluten, a protein found in wheat, barley, and rye, is more common in people with Down syndrome as well.

Hypothyroidism

Hypothyroidism occurs when the thyroid gland makes little or no thyroid hormone, needed to regulate temperature, energy, and other functions in the body. 

It can be present at birth or develop later in life, so regular testing for the condition should begin at birth for people with Down syndrome. Hypothyroidism can be managed by taking thyroid medications by mouth.

Blood Disorders

Down syndrome may lead to blood disorders like anemia, in which red blood cells don’t have enough iron to carry oxygen to the body, or polycythemia with higher-than-normal levels of red blood cells.

Childhood leukemia, a type of cancer that affects the white blood cells, occurs in about 2 to 3% of children with Down syndrome.

Seizure Disorders

Epilepsy, a seizure disorder, can occur early or later in life. A person with Down syndrome is most likely to be diagnosed with epilepsy in either the first two years of life, or after the third decade.

About half of the people with Down syndrome develop epilepsy after age 50.

Mental Health Disorders

It's also vital to understand that, despite what may appear to be innately unshakeable cheeriness, people with Down syndrome experience higher rates of conditions that include:

• Anxiety disorders
• Depression
• Obsessive-compulsive disorder 

These psychological problems can be successfully treated with behavior modification, counseling, and sometimes medication.