Down syndrome

Question 1

Tamara Taggart on the diagnostic process: Discussion

Answer 1

• What effect does the way professionals diagnose and provide information to parents about their child have on their expectations and parenting of the child?
• What should professionals be doing differently?

Question 2

Karen Gaffney advocate for Down Syndrome: Discussion

Answer 2

• Down syndrome is Karen Gaffney representative of people with DS?
  – She swam the English channel
  – She is articulate
  – She likely has average intelligence
• If not, then why should we take what she says seriously?

Question 3

Down syndrome: Due to a genetic mutation

Answer 3

• Most common chromosomal condition
• Most common cause of intellectual disability
• It is primarily caused by trisomy (3 copies) of chromosome 21
• Multiple systemic complications as part of the syndrome
• There is a wide range of phenotypic variation; every child is affected somewhat differently

Question 4

History

Answer 4

• John Langdon Down physician
  – Published description of people with Down syndrome as a distinct group
• Jérôme Lejeune physician
  – Down syndrome as a chromosomal condition
• In 2000, an international team of scientists successfully identified and catalogued each of the approximately 329 genes on chromosome 21

Question 5

Nondisjunction

Answer 5

• extra chromosome 21 (90-95% of all cases)
  – 75% egg 25% sperm carries extra
  genetic material

Question 6

Translocation

Answer 6

• part of chromosome 21 breaks off during cell division and attaches to another chromosome, typically chromosome 14
  – the total number of chromosomes in the cells remain 46, yet the presence of an extra part of chromosome 21 causes the characteristics of Down syndrome
  – Hereditary-passed on by mother or father
• 3-5% of all cases

Question 7

Mosaicism

Answer 7

• person received extra chromosome at fertilization but later during cell division the extra chromosome is lost
  –only some of the body cells have additional genetic material (2-5% of all cases)

Question 8

Screening versus Diagnosis

Answer 8

• Screening is the detection of risk factors or early signs of abnormalities in a healthy population (signs/symptoms may not be apparent)
• Diagnosis is the confirmation of a condition usually in a screen positive subgroup of the population (many may show symptoms of the condition)

Question 9

Diagnosis of DS

Answer 9

• Prenatal (before birth)
  1) chorionic villus sampling (CVS)
• Placental tissue is sampled (10-13 weeks gestation)
  2) amniocentesis
• carry up to a 1% risk of causing a spontaneous termination (miscarriage)
• Postnatal (after birth)
• 3) Karyotype
  – 100% accurate

Question 10

Rates of DS and associated factors

Answer 10

• Rates of Down syndrome: 1 in 792 live births

– Associated with maternal age
* 90% maternal nondisjunction
* 8% paternal nondisjunction
* 5% cell division after conception

– Maternal exposure to certain chemical solvents

– Maternal folate metabolism

Question 11

Medical complications of DS

Answer 11

• Most children with DS have cardiac, digestive, immunological, and/or respiratory conditions
• In 1950 a person with DS lived until approximately 12 years old
• Now people with DS can live to mid 40s, 60s or 70s
  – Lifespan has improved mostly due to medical interventions

Question 12

Genetic effects of DS: Two hypotheses

Answer 12

1) Gene dosage effects
– Extra copies of genes on chromosome 21 are over expressed and lead to the production of too many proteins
– may impact the expression of other genes
2) Developmental instability
– Broad alterations in developmental processes and dysregulation on biological systems

Question 13

Language development is most affected in DS

Answer 13

• Language is not a unitary ability
  – Different aspects of language influenced by different factors (one area could be weak and the other strong)
• Language development is shaped by environment and biology
  – Predispositions (face and voice capture attention)
  – Variations in exposure to language
• Language can be disrupted by delays in other areas (e.g., motor or social development)

Question 14

Phonology

Answer 14

• the system of rules about sounds and sound combinations for a language.
  – We have in American English approximately 48 different sounds that can be created by 26 letters
  – E.g., Sound out the word THREE. Now sound out the word THERE
  – C and H combined give us a new sound (e.g., child, porch, chew)
  – we have 14 - 16 possible sounds that can be created using these five vowels the most common sounds created by vowels in English: Heat, hit, pay, pet, hat, loot, foot, hut, the, father, hop, slow, soy, house, and light.

Question 15

morphology

Answer 15

• refers to the rules combining morphemes-the structure of words.
  – Morphemes are the smallest unit of linguistic meaning or function. E.g., sheep and dog but also suffix and prefix (“re” and “ness”)

Question 16

syntax

Answer 16

• the grammatical arrangement of words in sentences
• It governs how morphemes and words are correctly combined (e.g., “I ate the sandwich” and not “the sandwich ate I”

Question 17

pragmatics

Answer 17

• the study of the choices of language persons make in social interaction and of the effects of these choices on others. This area of language focuses on how language can be affected by context.
  – depending on the situation and the person to whom they are speaking. One might say, “Pass the salt” to a close or a familiar person or “Will you please pass the salt” to someone who is not
  – We normally simplify our language when speaking to young children. You would not tell a co-worker that you took the choo-choo train to work
  – Much of what we communicate can be implied and/or indirect
  – It takes social knowledge of the language, the culture and people to use correctly

Question 18

Many aspects of language development are affected in DS

Answer 18

• Most pronounced difficulty
  – Articulation problems
• Phonology (word sounds)
  – Grammatical
• Grammatical morphology (inflections)
• Vocabulary, syntax (word order)
• Better receptive than expressive language
• Fewer problems in pragmatics (use of language for social communication) as compared to other DD such as autism

Question 19

Social aspects of language development are affected in DS

Answer 19

• Desire to communicate is evident
  – More gesturing than typically developing children
• Sign language seems to promote verbal language
  – Some aspects of social communication are affected
• Joint attention is less

Question 20

Factors associated with language difficulties in DS

Answer 20

• Intelligibility and motor aspects of speech
  – Facial structure
  – Motor learning
  – Hearing
• Auditory verbal working memory
• Loss of syntax comprehension in early adulthood
  – Lack of stimulation
  – Related to Alzhiemer’s disease

Question 21

Example of early motor delays that may affect language

Answer 21

Interventions to improve speech motor development

Question 22

Short term memory (STM)
problems

Answer 22

• Poor Short-term memory (STM) in Down syndrome
• Could language deficits play a role?
  – (e.g., Subvocal rehearsal processes are weaker)

Question 23

Intervention approach that will be most effective considers the specific profile of DS

Answer 23

• Domains of development that may differ
  – Language
• much more proficient in receptive than expressive language
• show relative strengths in visual, short-term memory tasks
  – Motor
• motor delays early in development
• Emotional and social
• tend to be people-oriented
  – Behaviour
• Less maladaptive behavior and rarely severe psychiatric problems
  – Family
• parents of children with DS typically experience less stress as compared to parents coping with other developmental disabilities

Question 24

Behavioural Interventions are
most effective when…

Answer 24

• Consider the whole child within his/her family and community context
• Use developmentally appropriate techniques that scaffold the child’s development
• Target areas that will lead to the greatest overall developmental impact
• Accept differences that are adaptive

Question 25

Focus of intervention

Answer 25

• Current interventions focus is mostly on the child
• Some aspects of the intervention include parent coaching and parent-child interaction
• More peer or other oriented awareness and mediated intervention is needed

Question 26

Desired General Outcomes

Answer 26

• Improve social competence
• Develop executive function skills
• Foster independence
• Increase community participation
• Relieve family stress and improve resiliency
• Improve quality of life