What Are the Features of Down Syndrome?

The Impact of Down Syndrome on a Person's Life is Variable

Child, Down's Syndrome
Child, Down's Syndrome. Credit: BSIP / Contributor / Getty Images

In 1862, Dr. John Langdon Down noted that some of his patients shared a combination of distinct physical features, medical issues, and cognitive impairments.

Tying these similarities together, Down concluded that his patients had a specific syndrome. Down reported his observations in a medical journal and was the first to describe what we now know as Down syndrome. 

Physical Features of Down Syndrome

While not all people with Down syndrome share the exact same physical characteristics, there are some features that tend to occur in this genetic disorder.

This is why people with Down syndrome have a similar appearance. 

Three features that are found in nearly every person with Down syndrome are:

  • Epicanthic folds (extra skin of the inner eyelid, which gives the eyes an almond shape)
  • Upslanting palpebral fissures (slanting eyes)
  • Brachycephaly (a smaller head that is somewhat flattened in the back)

Other features that are seen in people with  Down syndrome (but are not in everyone) include light-colored spots in their eyes (these are called Brushfield spots), a small, somewhat flat nose, a small, open mouth with a protruding tongue, and low-set small ears that may be folded.

In their mouth, people with Down syndrome may have abnormal teeth, a narrow palate, and a tongue with deep fissures in it (this is called a furrowed tongue). They may also have round faces, short necks with the extra skin at the nape of the neck, and somewhat flatter profiles.

 

Other physical features seen in Down syndrome include a single crease across the palms of their hands as well as short stubby fingers with a fifth finger or pinky that curves inward (this is called clinodactyly). They often have straight hair that is fine and thin. In general, people with Down syndrome tend to be short in stature with short limbs.

They may also have a larger than normal space between the big and second toes and extra flexible joints. 

It's important to understand that none of these facial or physical features are abnormal by themselves, nor do they lead to or cause any serious problems. However, if a doctor sees these features together, they will likely suspect that the baby has Down syndrome.

Health Problems in Down Syndrome

In addition to their facial and physical features, children with  Down syndrome have a higher risk of developing a number of medical problems. 

Here are seven health problems people with Down syndrome may face:

Hypotonia

Almost all infants with Down syndrome have low muscle tone (hypotonia), meaning their muscles are weakened and appear somewhat floppy. Low muscle tone can make it more difficult to roll over, sit-up, stand and talk. In newborns, hypotonia can also cause feeding problems.

Many children with Down syndrome are delayed in reaching their motor milestones because of hypotonia. Hypotonia cannot be cured but it generally improves over time. Physical therapy can help improve muscle tone. Hypotonia may lead to orthopedic problems, another common issue related to a Down syndrome diagnosis.

 

Vision Problems

Vision problems are common in Down syndrome and the likelihood of having one increases as a person ages. Examples of such vision problems include nearsightedness (myopia), farsightedness (hyperopia), crossed-eyes ( strabismus), or shaking of the eye in a rhythmic pattern (nystagmus).

It is very important that children with Down syndrome have early eye exams since the majority of these vision problems are correctable.

Heart Defects

About 50 percent of babies with Down syndrome are born with heart defects. Some of these heart defects are mild and may correct themselves without medical intervention.

Other heart defects are more severe, requiring surgery or medication.

Hearing Loss 

Hearing problems are common in children with Down syndrome, especially otitis media, which affects about 50 to 70 percent and is a common cause of hearing loss. Hearing loss that is present at birth occurs in about 15 percent of babies with Down Syndrome. 

Gastrointestinal Problems

About 5 percent of infants with Down syndrome will have gastrointestinal issues such as a narrowing or blockage of the intestines (duodenal atresia) or an absent anal opening (anal atresia). Most of these malformations can be fixed with surgery. 

An absence of the nerves in the colon (Hirschsprung’s disease) is more common in people with Down syndrome than in the general population but is still quite rare. There is also a strong link between celiac disease and Down syndrome, meaning it is more common in people with Down syndrome than in the general population. 

Thyroid Problems

People with Down syndrome may also have problems with their thyroid gland—a small gland located in the neck—in that they don't produce enough thyroid hormone, which can result in hypothyroidism. Hypothyroidism is most often treated by taking replacement thyroid hormone. This medication must be taken for the rest of the person’s life. Hyperthyroidism (meaning an overactive thyroid gland) may also occur in people with Down syndrome. 

 Leukemia

Very rarely, about 1 percent of the time, an individual with Down syndrome can develop leukemia. Leukemia is a type of cancer that affects the blood cells in the bone marrow. Symptoms of leukemia include easy bruising, fatigue, a pale complexion, and unexplained fevers. Although leukemia is a very serious disease, the survival rate is high. Typically leukemia is treated with chemotherapy, radiation, or a bone marrow transplant.

Intellectual Issues in Down Syndrome

Everyone with Down syndrome has some degree of intellectual disability. People with Down syndrome tend to learn slower and have difficulties with complex reasoning and judgment. It is impossible to predict what level of intellectual disability those born with Down syndrome will have—although, this will become clearer as they age. 

There is a wide range of mental abilities among people with Down syndrome. The IQ range—measure of intelligence—for normal intelligence is between 70 and 130. A person is considered to have a mild intellectual disability if their IQ is between 55 and 70. A moderately intellectually disabled person has an IQ of between 40 and 55. Most individuals with Down syndrome score within the mild to moderate range.

Despite their IQ, people with Down syndrome can learn. There is often a misconception that those with Down syndrome have a predetermined ability to learn. We know now that people with Down syndrome develop over the course of their lifetime and have the potential to learn. This potential can be maximized through early intervention, good education, higher expectations, and encouragement.

A Word From Verywell

It is important to remember that no one person with Down syndrome will have all of the features, health conditions, or intellectual problems described here. Nor does the number of physical problems a person with Down syndrome has correlate with their intellectual ability. Each and every person with Down syndrome has their own unique personality and strengths.

Sources:

Mundakel GT. (January 2017). Down syndrome. Emedicine

Ostermaier, KK. (November 2015). Down syndrome: Clinical features and diagnosis. In: UpToDate, Drutz JE, Firth HV (Ed), UpToDate, Waltham, MA.

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