Down syndrome history and symptoms

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

History and Symptoms

Down syndrome symptoms vary from person to person and can range from mild to severe. However, children with Down syndrome have a widely recognized appearance. The head may be smaller than normal and abnormally shaped. For example, the head may be round with a flat area on the back. The inner corner of the eyes may be rounded instead of pointed.

• Common physical signs of down syndrome include:
  • Decreased muscle tone at birth
  • Excess skin at the nape of the neck
  • Flattened nose
  • Separated joints between the bones of the skull (sutures)
  • Single crease in the palm of the hand
  • Small ears
  • Small mouth
  • Upward slanting eyes
  • Wide, short hands with short fingers
  • White spots on the colored part of the eye (Brushfield spots)
  • Physical development is often slower than normal.
  • Most children with Down syndrome never reach their average adult height.
• Children may also have delayed mental and social development. Common problems may include:
  • Impulsive behavior
  • Poor judgment
  • Short attention span
  • Slow learning
  • As children with Down syndrome grow and become aware of their limitations, they may also feel frustrated and angry.
• Many different medical conditions are seen in people with Down syndrome, including:
  • Birth defects involving the heart:
    • Atrial septal defect
    • Ventricular septal defect
  • Dementia may be seen
  • Eye problems, such as cataracts (most children with Down syndrome need glasses)
  • Early and massive vomiting, which may be a sign of a gastrointestinal blockage, such as esophageal atresia and duodenal atresia
  • Hearing problems, probably caused by regular ear infections
  • Hip problems and risk of dislocation
  • Long-term (chronic) constipation
  • Sleep apnea (because the mouth, throat, and airway are narrowed in children with Down syndrome)
  • Teeth that appear later than normal and in a location that may cause problems with chewing
  • Underactive thyroid (hypothyroidism)

The condition is characterized by a combination of major and minor differences in structure. Often Down syndrome is associated with some impairment of cognitive ability and physical growth as well as facial appearance. Down syndrome can be identified during pregnancy or at birth.

Individuals with Down syndrome can have a lower than average cognitive ability, often ranging from mild to moderate learning disabilities. Developmental disabilities often manifest as a tendency toward concrete thinking or naïveté. A small number have severe to profound mental disability.

Many of the common physical features of Down syndrome also appear in people with a standard set of chromosomes. They may include a single transverse palmar crease (a single instead of a double crease across one or both palms), an almond shape to the eyes caused by an epicanthic fold of the eyelid, upslanting Palpebral fissures, shorter limbs, poor muscle tone, a larger than normal space between the big and second toes, and protruding tongue. Health concerns for individuals with Down syndrome include a higher risk for congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions.

Early childhood intervention, screening for common problems, medical treatment where indicated, a conducive family environment, and vocational training can improve the overall development of children with Down syndrome. Although some of the physical genetic limitations of Down syndrome cannot be overcome, education and proper care will improve quality of life.

Characteristics

Example of white spots on the iris known as Brushfield spots

Individuals with Down syndrome may have some or all of the following physical characteristics: oblique eye fissures with epicanthic skin folds on the inner corner of the eyes, muscle hypotonia (poor muscle tone), a flat nasal bridge, a single palmar fold, a protruding tongue (due to small oral cavity, and an enlarged tongue near the tonsils), a short neck, white spots on the iris known as Brushfield spots, excessive flexibility in joints, congenital heart defects, excessive space between large toe and second toe, a single flexion furrow of the fifth finger, and a higher number of ulnar loop dermatoglyphs. Most individuals with Down syndrome have mental retardation in the mild (IQ 50–70) to moderate (IQ 35–50) range, with scores of children having Mosaic Down syndrome (explained below) typically 10–30 points higher. In addition, individuals with Down syndrome can have serious abnormalities affecting any body system.

Cognitive development

Cognitive development in children with Down syndrome is quite variable. It is not currently possible at birth to predict the capabilities of any individual reliably, nor are the number or appearance of physical features predictive of future ability. The identification of the best methods of teaching each particular child ideally begins soon after birth through early intervention programs. Since children with Down syndrome have a wide range of abilities, success at school can vary greatly, which stresses the importance of evaluating children individually. The cognitive problems that are found among children with Down syndrome can also be found among typical children. Therefore, parents can use general programs that are offered through the schools or other means. Language skills show a difference between understanding speech and expressing speech. It is not uncommon for children with Down Syndrome to have a speech delay, although it is common for them to need speech therapy to help with expressive language. Fine motor skills are delayed and often lag behind gross motor skills and can interfere with cognitive development. Gross Motor Skills can be affected anywhere from minor to major. Some children will walk at around 2 while others around 4. A physical therapist or APE will help a child with this.

Speech therapy is usually performed because of the enlarged tongue which many children with Down Syndrome have, which makes clear speech difficult. Speech therapy and immersion in social situations where conversation is common and extended can result in excellent language development. Unfortunately, relatively little is done in early intervention programs to foster cognitive development. A good Montessori school may be an excellent environment for fostering learning in individuals with Down Syndrome. Significant work on cognitive development has been done by Dr. Raymundo Veras of Brazil. Dr. Veras worked from the model of early childhood education established by Glenn Doman of the Institutes for the Achievement of Human Potential, in Philadelphia. As a result of his work, he wrote a book entitled Children of Dreams, Children of Hope, in which he recounts demonstrating to Mr. Doman a preschool age girl who was able to read in four languages and play the violin. Children with Down Syndrome often have an enhanced ability to memorize songs, stories, vocabulary, and other language material, which can be capitalized upon.

In education, mainstreaming of children with Down syndrome is becoming less controversial in many countries. For example, there is a presumption of mainstream in many parts of the UK. Mainstreaming is the process whereby students of differing abilities are placed in classes with their chronological peers. Children with Down syndrome may not age emotionally/socially and intellectually at the same rates as children without Down syndrome, so over time the intellectual and emotional gap between children with and without Down syndrome may widen. Complex thinking as required in sciences but also in history, the arts, and other subjects can often be beyond the abilities of some, or achieved much later than in other children. Therefore, children with Down syndrome may benefit from mainstreaming provided that some adjustments are made to the curriculum.

Some European countries such as Germany and Denmark advise a two-teacher system, whereby the second teacher takes over a group of children with disabilities within the class. A popular alternative is cooperation between special schools and mainstream schools. In cooperation, the core subjects are taught in separate classes, which neither slows down the typical students nor neglects the students with disabilities. Social activities, outings, and many sports and arts activities are performed together, as are all breaks and meals.

Health

The medical consequences of the extra genetic material in Down syndrome are highly variable and may affect the function of any organ system or bodily process. The health aspects of Down syndrome encompass anticipating and preventing effects of the condition, recognizing complications of the disorder, managing individual symptoms, and assisting the individual and his/her family in coping and thriving with any related disability or illnesses.

The most common manifestations of Down syndrome are the characteristic facial features, cognitive impairment, congenital heart disease (typically a ventricular septal defect), hearing deficits (maybe due to sensory-neural factors, or chronic serous otitis media, also known as Glue-ear), short stature, thyroid disorders, and Alzheimer's disease. Other less common serious illnesses include leukemia, immune deficiencies, and epilepsy. However, health benefits of Down syndrome include greatly reduced incidence of many common malignancies except leukemia and testicular cancer — although it is, as yet, unclear whether the reduced incidence of various fatal cancers among people with Down syndrome is as a direct result of tumor-suppressor genes on chromosome 21, because of reduced exposure to environmental factors that contribute to cancer risk, or some other as-yet unspecified factor. Down syndrome can result from several different genetic mechanisms. This results in a wide variability in individual symptoms due to complex gene and environment interactions. Prior to birth, it is not possible to predict the symptoms that an individual with Down syndrome will develop. Some problems are present at birth, such as certain heart malformations. Others become apparent over time, such as epilepsy.

These factors can contribute to a significantly shorter lifespan for people with Down syndrome. One study, carried out in the United States in 2002, showed an average lifespan of 49 years, with considerable variations between different ethnic and socio-economic groups.

Fertility amongst both males and females is reduced, with only three recorded instances of males with Down syndrome fathering children.

Endocrinology and hematology

Individuals with DS are at increased risk for dysfunction of the thyroid gland, an organ which helps control metabolism. Low thyroid (hypothyroidism) is most common, occurring in almost a third of those with DS. This can be due to absence of the thyroid at birth (congenital hypothyroidism) or due to attack on the thyroid by the immune system. Reproduction is also affected by DS. Women with DS are less fertile and often have difficulties with miscarriage, premature birth, and difficult labor. However, women with DS are capable of having children without the extra chromosome 21 of DS. Men with DS are almost uniformly infertile, exhibiting defects in spermatogenesis.

Hematologic malignancies such as leukemia are more common in children with DS. In particular, the risk for acute lymphoblastic leukemia is at least 10 times more common in DS and for the megakaryoblastic form of acute myelogenous leukemia is at least 50 times more common in DS. Transient leukemia is a form of leukemia which is rare in individuals without DS but affects up to 20 percent of newborns with DS. This form of leukemia is typically benign and resolves on its own over several months, though it can lead to other serious illnesses. In contrast to hematologic malignancies, solid tumor malignancies are less common in DS, possibly due to increased numbers of tumor suppressor genes contained in the extra genetic material.

Gastrointestinal and growth

Down syndrome increases the risk of Hirschsprung's disease, in which the nerve cells that control the function of parts of the colon are not present. This results in severe constipation. Other congenital anomalies occurring more frequently in DS include duodenal atresia, annular pancreas, and imperforate anus. Gastroesophageal reflux disease and celiac disease are also more common among people with DS.

Growth parameters such as height, weight, and head circumference are smaller in children with DS than with individuals of the same age. Adults with DS tend to have short stature — the average height for men is 5 feet 1 inch (157 cm) and for women is four feet 9 inches (144 cm). Individuals with DS are also at increased risk for obesity as they age.

Axial Skeleton

Persons with down syndrome are at higher than normal risk for atlanto-axial instability, probably due to ligamental laxity. Periodic screening, with cervical x-rays, is recommended to identify this abnormality.

Neurology

The neurologic consequences of DS manifest early in life. Infants with Down Syndrome have a decreased muscle tone and are more flexible. Mental retardation becomes apparent as individuals with DS grow and develop — sitting, walking, and talking are typically delayed. Children and adults with DS are at increased risk for developing epilepsy. The risk for Alzheimer's disease is increased in individuals with DS, with 10-25% of individuals with DS showing signs of AD before age 50, up to 50% with clinical symptoms in the sixth decade, and up to 75% in the 7th decade. This sharp increase in the incidence and prevalence of dementia may be one of the factors driving the decreased life expectancy of persons with Down Syndrome.

Ophthalmology and otolaryngology

Eye disorders are more common in people with DS. Almost half have strabismus, in which the two eyes do not move in tandem. Refractive errors requiring glasses or contacts are also common. Cataracts (opacity of the lens) and glaucoma (increased eye pressures) are also more common in DS.

Hearing loss affects more than half of individuals with DS, due to multiple factors. Frequent infections of the middle ear (otitis media) and obstructive sleep apnea are also more common DS. Instability of the atlanto-axial joint occurs in ~15% of people with DS and may lead to the neurologic symptoms of spinal cord compression.