UNIT 7 LEARNERS WITH DOWN SYNDROME
Key Unit Competence: Explain the characteristics of leaners with Down
syndrome and use appropriate methods to teach
themINTRODUCTORY ACTIVITY
Observe those pictures and respond to the following questions:
1. What are common physical features do the children on the pictures
have?
2. At your school, surrounding areas or in your community, have you
seen or met someone with the same physical features? If yes what
other characteristics have you observed about that person (in regard
to his/her intellectual abilities, speech or communication skills, social
skills, etc)
7.1. Definition, causes and types of Down syndrome
ACTIVITY 7.1
– What is the Definition of Down syndrome?
– What causes Down syndrome– Types of Down syndrome
7.1.1. What is Down syndrome?
Down syndrome is a condition in which a person has an extra chromosome.
Chromosomes are small “packages” of genes in the body. They determine how
a baby’s body forms during pregnancy and how the baby’s body functions
as it grows in the womb and after birth. Typically, a baby is born with 46
chromosomes. Babies with Down syndrome have an extra copy of one of these
chromosomes, chromosome 21. A medical term for having an extra copy of a
chromosome is ‘trisomy.’ Down syndrome is also referred to as Trisomy 21.
This extra copy changes how the baby’s body and brain develop, which can
cause both mental and physical challenges for the baby.
Why is Down Syndrome Referred to as a genetic condition?
The human body is made of cells; all cells contain a centre, called a nucleus, in
which genetic material is stored. This genetic material, known as genes, carries
the codes responsible for all our inherited characteristics. Genes are grouped
along rod-like structures called chromosomes. Normally, the nucleus of each
cell contains 23 pairs of chromosome, half of which are inherited from each
parent. In individuals with Down syndrome, however, the cells usually contain
47, not 46, chromosomes; the extra chromosome is the 21st. This excess genetic
material, in the form of additional genes along chromosome 21, results in Down
syndrome. The extra 21st chromosome is detected by using a procedure called
a karyotype. A karyotype is a visual display of the chromosomes grouped by
size, number and shape. Chromosomes may be studied by examining blood
or tissue cells. Individual chromosomes are identified, stained and numbered
from largest to smallest. Ninety-five percent of occurrences of Down syndrome
result from the presence of an extra (third) chromosome, a condition described
as Trisomy 21.
7.1.2. The cause of Down syndrome
Down syndrome is usually caused by an error in cell division called
nondisjunction. However, two other types of chromosomal abnormalities,
mosaicism and translocation, are also implicated in Down syndrome although
to a much lesser extent. Regardless of the type of Down syndrome a person
may have, all people with Down syndrome have an extra, critical portion of
chromosome 21 present in all or some of their cells. This additional genetic
material alters the course of development and causes the characteristics
associated with the syndrome.
Nondisjunction: Nondisjunction is a faulty cell division that results in
an embryo with three copies of chromosome 21 instead of the usual two.
Prior to or at conception, a pair of 21st chromosomes in either the sperm or
the egg fails to separate. As the embryo develops, the extra chromosome is
replicated in every cell of the body. This error in cell division is responsiblefor 95 percent of all cases of Down syndrome.
During fertilization, the 23 chromosomes from the egg and sperm combine. The resulting fertilized
egg has 46 chromosomes. During mitosis, the cell replicates itself and divides into two cellswith 46 chromosomes in each.
Nondisjunction is the failure of the pair of chromosomes to separate during meiosis, which is the
process by which egg and sperm cells replicate themselves and divide. Nondisjunction results inboth 21stchromosomes being carried to one cell and none to the other.
Note: It is not currently known why nondisjunction occurs, although researchhas shown that it increases in frequency as a woman ages.
Incidence of Down syndrome and maternal age
7.1.3. Types of Down syndrome
There are three types of Down syndrome. People often can’t tell the difference
between each type without looking at the chromosomes because the physical
features and behaviors are similar.
• Trisomy 21: About 95% of people with Down syndrome have Trisomy
21. With this type of Down syndrome, each cell in the body has 3
separate copies of chromosome 21 instead of the usual 2 copies.
• Translocation Down syndrome: This type accounts for a small
percentage of people with Down syndrome (about 3%). This occurs
when an extra part or a whole extra chromosome 21 is present, but it
is attached or “trans- located” to a different chromosome rather than
being a separate chromosome 21.
• Mosaic Down syndrome: This type affects about 2% of the people
with Down syndrome. Mosaic means mixture or combination. For
children with mosaic Down syndrome, some of their cells have 3
copies of chromosome 21, but other cells have the typical two copies of
chromosome 21. Children with mosaic Down syndrome may have the
same features as other children with Down syndrome. However, they
may have fewer features of the condition due to the presence of some(or many) cells with a typical number of chromosomes.
SELF-ASSESSMENT 7.1
1. What is Down syndrome?
2. In few words explain the cause of Down syndrome
3. List three types of Down syndrome
7.2. Characteristics of children with Down syndrome and
strategies to teach them
ACTIVITY 7.1
– What are characteristics of children with Down syndrome
– What are strategies to help children with Down syndrome inthe classroom
7.2.1. Characteristics of children with Down syndrome
Children with Down syndrome can be identified based on their body shape and
size, facial features, intellectual or learning ability.
a. Identifying a child with Down syndrome by body shape and size Look for low muscle tone
Babies with low muscle tone are usually described as floppy or feeling like a
“rag doll” when held. This condition is known as hypotonia. Infants usually
have flexed elbows and knees, whereas those with low muscle tone have loosely
extended joints.
• While infants with normal tone can be lifted and held from under the
armpits, babies with hypotonia typically slip from their parents’ hands
because their arms rise without resistance.
• Hypotonia results in weaker stomach muscles. Therefore, the stomach
may extend outward more than usual.
• Poor muscle control of the head (head rolling to the side or forward
and backward) is also a symptom. Look for shortened height
Children affected by Down syndrome often grow slower than other children,
and are therefore shorter in stature. Newborns with Down syndrome are
usually small, and a person with Down syndrome will most likely remain short
through adulthood. A study conducted in Sweden shows that the mean birth
length is 48 centimeters (18.9 inch) for both males and females with Down
syndrome. In comparison, the average length for those without the disability
is 51.5 cm. Look for a short and wide neck
Also look for excess fat or skin surrounding the neck. In addition, neck instability
tends to be a common issue. While neck dislocation is uncommon, it is more
likely to occur in people with Down syndrome than those without the disability.
It is necessary to be aware of a lump or pain behind the ear, a stiff neck that
doesn’t heal quickly, or changes in the way a person walks (appearing unsteadyon their feet).
Look for short and stocky appendages
This includes legs, arms, fingers, and toes. Those with Down syndrome often
have shorter arms and legs, a shorter torso, and higher knees than those
without it.
• People with Down syndrome often have webbed toes, which is
distinguished by the fusing together of the second and third toe.
• There may also be a wide space between the big toe and second toe,
and a deep crease on the sole of the foot where this space is.
• The fifth finger (pinky) can sometimes only have 1 flexion furrow, or
place where the finger bends.
• Hyper flexibility is also a symptom. This is identifiable by joints that
seem to easily extend beyond the normal range of motion. A child with
Down syndrome may easily “do the splits,” and may be at risk of falling
over as a result.
• Having one singular crease across the palm of the hand, and a pinky
finger that curves towards the thumb are additional characteristics.
b. Identifying a child with Down syndrome by facial features Look for a small, flat nose
Many people with Down syndrome are described as having flat, rounded, wide
noses with small nasal bridges. The nasal bridge is the flat section of the nose
between the eyes. This area can be described as being “pushed in. Look for slanted eye shape
Those with Down syndrome usually exhibit round eyes that slant upwards.
While the outer corners of most eyes usually turn downward, those with Down
syndrome have eyes that turn upward (almond-shaped). Look for small ears
People with Down syndrome tend to have smaller ears that are set lower on the
head. Some may have ears whose tops fold over slightly. Look for an irregularly shaped mouth, tongue, and/or teeth
Due to low muscle tone, the mouth may appear to be turned downward and
the tongue may protrude from the mouth. Teeth may come in later and in a
different order than usual. Teeth may also be small, unusually shaped, or out
of place.
c. Identify learners with Down syndrome by looking at their
developmental and intellectual abilities
All people with Down syndrome experience cognitive delays, however, the
effect is usually mild to moderate and is not indicative of the many strengths
and talents that each individual possesses. Children with Down syndrome learn
to sit, walk, talk, play, toilet train and do most other activities only somewhat
later than their peers without Down syndrome.
Speaking may or may not pose a challenge for an individual with Down syndrome.
It all depends on the person. Some learn sign language or another form of
alternative communication instead of speaking. People with Down syndrome
easily grasp new words and their vocabularies become more advanced as they
mature. Because grammar rules are inconsistent and hard to explain, those
with Down syndrome may have difficulty mastering grammar. As a result, they
usually use shorter sentences with less detail. Expression can be hard for them
because their motor skills are impaired. Speaking clearly may also present a
challenge. Many people with Down syndrome benefit from speech therapy.Developmental Milestones
7.2.2. Strategies to help learners with Down syndrome
– Use teaching methods that involve cues and objects
– Pair pictures with spoken words
– Present information visually (e.g. overhead projector, posters, pocket
charts, chalkboard)
– Use simple directions
– Break down directions into small steps
– Allow adequate response time
– Assign fewer problems to a page
– Give students more freedom to choose their work activities
– Foster independence and self-reliance by balancing developmental
and chronological needs as higher academic expectations are set in the
classroom
– When presenting independent work, try to divide it into small segments
(e.g. fold test in half).
– Allow extra time to complete tasks. Reduce length of assignments
– Avoid large group and whole class instruction as they are least effective
– Be aware that some students may lack the fine motor coordination to
use a keyboard and mouse effectively.
– Assistive and/or adaptive equipment such as specialized key guards or
alternative keyboard can be used
– Minimize distractions. When choosing stimuli or objects, ensure that
they have clear and obvious dimensions that vary on as few dimensions
as possible (e.g., colour, size, texture)
– Pay attention to seating. Avoid seating students with Down syndrome
near a window, door or high traffic area
– Give immediate feedback or praise to ensure that students associaterewards with their efforts
SELF-ASSESSMENT 7.2
1. Identify the characteristics of children with Down syndrome
2. Explain 5 approaches to teach learners with Down syndrome
SKILLS LAB
Visit a special center or school that have children with different types of
disabilities. Identify children with Down syndrome. Observe identified
children/child in the classroom during teaching time. Finally, advice the
teacher in regards to suitable teaching approaches to be used in order
to respond to the needs of these learners with Down syndrome.
END OF UNIT ASSESSMENT
1. What is Down syndrome?
2. What does nondisjunction mean?
3. In few words, explain why Down syndrome is referred to as a
genetic condition?
4. How can you identify a child with Down syndrome?
5. List 5 approaches to be used when teaching learners with Downsyndrome