Down Syndrome
Features Common to Down Syndrome


Down Syndrome is a birth defect which takes place when an individual possesses three copies of chromosome 21, instead of the normal two copies. This extra genetic material changes the individuals course of development and causes certain characteristics linked to Down Syndrome. One in every 733 babies is born with Down Syndrome making DS the most common chromosomal condition. Some common features related to Down Syndrome are upward slanting eyes, shorter stature, and a deep crease in the middle of the palm. Every individual is different and may or may not possess these characteristics. The life expectancy of these individuals used to be 25 years in 1983 and today only 27 years later the life expectancy is 60 years.

Causes An error in cell division called "nondisjunction" is what typically causes Down Syndrome. Nondisjunction refers to the embryo having three copies of chromosome 21 instead of the standard two. Nondisjunction is responsible for 95% of Down Syndrome cases. Nondisjunction is also referred to as Trisomy 21. There are two other types of Down Syndrome called "Mosaicism" and "Translocation", but they are less common. "Mosaicism" occurs when the nondisjunction of chromosome 21 takes place in only one but not all cell division after fertilization. There is then a combination of two types of cells, some with the usual 46 chromosomes and others with 47, resulting in the extra chromosome 21."Mosaicism" accounts for only 1% of cases of Down Syndrome. "Translocation" happens when part of chromosome 21 breaks off and attaches to another chromosome. The ending result of chromosomes is 46, however there is still the extra part of chromosome 21 present. "Translocation" accounts for 4% of Down Syndrome Cases. One well known fact is that the chances for "nondisjunction" happening increases as a woman ages. At the age of thirty-five a woman would have a 1 in 350 chance of having a child with down syndrome. At the age of forty the number jumps to a 1 out of 100 chance and at age forty-five the number dramatically changes to a 1 out of 30 chance of conceiving a child with
Down Syndrome.

Trisomy 21

Effects On the Systems

Nervous System

All controlled and involuntary bodily functions are controlled by your central nervous system. The nervous system in relation to Down Syndrome affects the brain, spinal cord, spinal and cranial nerves. This disorder impacts the individual’s intelligence, physical capabilities and learning capabilities. Developmental disabilities,hypotonia, atlantoaxial dislocation and seizures are among the most common effects related to the nervous system for those with Down Syndrome. This is the most impacted system in our bodies with someone born with Trisomy 21, otherwise known as Down Syndrome. Here is a list of less common effects, all controlled by the nervous system: dementia, hearing loss, gastrointestinal blockage, thyroid problems, dysphagia, obesity, skeletal problems, poor vision, behavioral problems, and significant speech and language delays. There are also more severe complications such as convulsions, heart complications, and movement disorders that hinder gross and fine motor skills. The nervous system allows voluntary and involuntary muscle control of the regulatory process of breathing, having your heart beat, controlling your body temperature, hunger and other processes of life, and cognitive skills. These controls are all relays that are suppressed by the moderate to severe brain deformation caused by Down Syndrome. These affect sensory information when sent to the brain, vision, hearing and various nerves that innervate every part of your body.


Research and different studies show that being born with Down Syndrome gives you an increased risk of certain medical conditions related to the airway, lungs, nasal cavity, oral cavity, epiglottis, vocal cords, pharynx, larynx, esophagus, trachea, lungs, heart, and diaphragm. With the medical advancement of today, the majority of these individuals can now be surgically treated and corrected with a greater number of positive results, causing long term health improvements. Due to the abnormalities they are born with, Individuals with DS are also at a higher risk for infectious disease. Their immune system is also compromised and is susceptible to infection like pneumonia. A very common trait of DS is having a small mouth with a large tongue that protrudes forward, this can cause sleep apnea. Other causes of sleep apnea include large adenoids, low muscle tone of the throat, and increased secretions. In addition, low muscle tone also known as "hypotonia" can be in any of the muscles used for respiration for an individual with Down Syndrome. There is also soft tissue and skeletal alterations that lead to airway obstruction.

Phonatory System

Phonation is the process of the airstream passing through the vocal folds producing vibrations and in turn producing speech sounds. As previously mentioned those with Down Syndrome have low muscle tone that may result in the muscles in the vocal folds not coming together or the muscles of the larynx not working properly. Also, those with DS typically have narrowed airways which affects voicing because the airway is more constricted than normal.


Articulation and Phonation are very similar and each process is related to each other. High frequency sounds are recognized by the brain and provide it with energy. In speech, higher frequency range is concentrated mostly in the tone of the voice. Individuals with DS who have poor articulation, lack tone and have poor high frequency content. This provides little energy to the brain and requires a lot of energy to be emitted. Therefore, this results in depletion of energy, affects many of their language expression and also affects the thinking process as well as body functions such as poor posture, balance, and coordination skills. It also affects lateral dominance which is a common trait in an individual with Down Syndrome . A large tongue is also a common feature for an individual with Down Syndrome to have. The protruding tongue can affect speech and language at a later developmental stage in their life if therapy is not introduced. Resulting from the problems with the tongue many individuals suffer from Dysphagia, which is a swallowing disorder.


Individuals with Down Syndrome have difficulty learning how to process tones. This is a result of the brain’s auditory input being disrupted or interfered with. Good speech and language development starts with acute hearing and sensitivity to certain sound frequencies and good tonal processing. Many people with the disorder develop congestion, ear infections and chronic fluid in the ears causing problems for the development of good speech and language. They tend to have many hearing problems related to the auditory system. These individuals are born with narrow eustachian tubes and low muscle tone which leads to the middle ear not draining well. The cycle of problems and factors of DS lead to underdeveloped normal auditory tonal processing, and not being able to hear tones or being able to process or develop language. Those with Down Syndrome are also prone to middle ear infections.The ear is actively involved in the process of language and in auditory control of speech. Poor muscle tone slows the movement of the middle ear muscles affecting the auditory process and control of speech. A person with Down Syndrome also has a lower processing rate which prevents them from hearing shorter words, especially conjunctions and articles that are critical in sentence formation. This leads the individuals to use single or multiple words instead of using complete sentences.

Overall Effect On Speech Production

Children with Down Syndrome typically are strong in the area of pragmatics and vocabulary. They usually have very good social interactive skills. Syntax and morphology are typically their most challenging areas. Those with Down Syndrome typically have a stronger receptive language rather than expressive language. As a result of the low facial muscle tone in many of those with Down Syndrome they may have articulation problems and may leave off ending sounds of words. Also, because those with Down Syndrome are prone to chronic ear infections and have narrow ear canals they are at a risk for hearing loss. Even mild hearing loss can result in language and articulation issues. Individuals with Down Syndrome are at a greater risk of obstructive sleep apnea and because of this they lose sleep. This loss of sleep causes lethargic behavior and can lead to disruption in learning. The sleep apnea may be brought on by an obstruction of a large tongue which can also lead to difficulties with speech and articulation.


All of our body systems are so closely related to each other that they affect other functions within our bodies. A child born with Down Syndrome initially presents many moderate to serve medical challenges, as well as future academic challenges that will arise as time progresses. The children have to overcome many obstacles that will impede their progress over and above their complex nature. With the aid of interactive learning they will overcome difficult obstacles and early intervention will help develop much better speech, language,and cognitive skills. Also, as a result of this interactive learning process those with Down Syndrome will enjoy a much happier, improved, quality of life. They will also be able to communicate much clearer in life after being given the tools that they lack in intelligibility to help them overcome their obstacles.


National Association for Down Sydrome

National Down Syndrome Society

**National Down Sydrome Congress Center**


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