CD: CDC and AS Flashcards

1
Q

What is Cri-du-chat syndrome?

A

Chromsomal condition resulting from missing piece of chromosome 5

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2
Q

What is the prevalence of Cri-du-chat syndrome?

A

1 in 20,000 - 50,000 newborns

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3
Q

Summarise the aetiology of Cri-du-chat syndrome (3)

A
  1. Spontaneous deletion during embryo formation or development
  2. Deletion of the end of the short (p) arm of chromosome 5 (5p-)
  3. 10% inherit abnormality from unaffected parent
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4
Q

How does the aetiology vary in Cri-du-chat syndrome? (3)

A
  1. Symptoms are probably related to the loss of multiple genes on the short arm of chromosome 5
  2. Size of deletion varies between individuals
  3. Larger deletions = more severe intellectual disability and developmental delay
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5
Q

What gene is associated with severe intellectual disability?

A

CTNND2 loss

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6
Q

Explain the inheritance pattern of Cri-du-chat syndrome (3)

A
  1. Unaffected parent carries a chromosomal rearrangement called a balanced translocation
  2. Becomes unbalanced as passed to next generation
  3. Children are missing genetic material from the short arm of chromosome 5
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7
Q

Summarise the impact of Cri-du-chat syndrome (6)

A
  1. High pitched cry
  2. Intellectual disability
  3. Distinctive facial features
  4. Physical development
  5. Health difficulties
  6. Behavioural problems
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8
Q

What are 4 distinctive facial features of Cri-du-chat syndrome?

A
  1. Widely set eyes (hypertelorism)
  2. Low-set ears
  3. Small jaw
  4. Rounded face
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9
Q

What are 5 physical development characteristics in Cri-du-chat syndrome?

A
  1. Delayed development
  2. Small head size (microcephaly)
  3. Low birth weight
  4. Hypotonia in infancy
  5. Some born with heart defect
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10
Q

What is the variation in intellectual impairment in Cri-du-chat syndrome?

A
  1. Most have moderate-severe learning difficulty

2. Some will have mild

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11
Q

What are 7 associated health difficulties in Cri-du-chat syndrome?

A
  1. Scoliosis
  2. Constipation
  3. Reflux
  4. Respiratory tract infections
  5. Feeding difficulties
  6. Flat footedness
  7. Renal and heart problems
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12
Q

What are 3 behavioural problems found in Cri-du-chat syndrome?

A
  1. Hyperactivity
  2. Sleep difficulties
  3. ASD (30% meet cut off)
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13
Q

How is Cri-du-chat syndrome diagnosed?

A
  1. Evaluation of medical history and symptoms

2. Genetic testing

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14
Q

What is the prognosis of Cri-du-chat syndrome? (4)

A
  1. Most have normal life expectancy
  2. After 1st year = mortality and morbidity rates are low
  3. Serious organ defects may have worse prognosis
  4. Older children usually able to move, communicate verbally/sign and independent in self-care skills
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15
Q

What is the treatment of Cri-du-chat syndrome?

A

Early intervention in physio, SLT, behavioural modification and special education

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16
Q

What is Angelman syndrome?

A
  1. Complex genetic disorder that primarily affects the nervous system
  2. Causes severe physical and intellectual disability
17
Q

What is the prevalence of Angelman syndrome?

A

1/12,000 - 20,000

18
Q

Summarise the impacts of Angelman syndrome (6)

A
  1. Delayed development
  2. Intellectual disability
  3. Ataxia
  4. Seizures
  5. Happy, excitable personality
  6. Physical appearance
19
Q

Describe the physical appearance of Angelman syndrome (4)

A
  1. “Coarse” facial description
  2. Unusually fair skin and light-coloured hair
  3. Small head size
  4. Crossed eyes (strabismus)
20
Q

What are behavioural characteristics of Angelman syndrome? (5)

A
  1. Hyperactivity
  2. Short attention span
  3. Fascination with water
  4. Sleep difficulties
  5. Frequent laughing, smiling and hand-flapping
21
Q

What is the “coarse” facial description of Angelman syndrome? (3)

A
  1. Lack usual fine and sharp facial appearance
  2. Rounded and heavy appearance with thickened skin
  3. Subcutaneous or bony tissues
22
Q

Summarise the aetiology of Angelman syndrome (3)

A
  1. Spontaneous genetic changes during formation of reproductive cells or early embryonic development
  2. Unknown in 10-15%
  3. Small percentage: paternal uniparental disomy
23
Q

What is parternal uniparent disomy in Angelman syndrome?

A

Inherits 2 copies of chromosome 15 from father rather than one from each parent

24
Q

What causes light-coloured hair and fairskin in Angelman syndrome?

A

Loss of gene OCA2 located on chromosome 15

25
What mutations cause Angelman syndrome? (2)
1. 70% due to deletion in maternal chromosome 15 containing UBE3A gene 2. 11% caused by mutation in maternal copy of UBE3A gene
26
What is the inheritance pattern of Angelman syndrome?
1. Rare that a genetic change is responsible | eg. mutation in the UBE3A gene or nearby region of DNA is passed to the next generation
27
How is Angelman syndrome diagnosed? (2)
1. Physical exam of symptoms | 2. Genetic testing
28
Give 4 types of genetic testing used to diagnosis Angelman syndrome
1. Chromosome analysis eg. deletions 2. Fluorescent in situ hybridisations eg. chromosome 15 deletions 3. DNA methylation 4. UBE3A gene mutation analysis
29
Summarise the treatment of Angelman syndrome (5)
1. Anti-epileptic drugs 2. Physiotherapy 3. Back brace/spinal surgery to prevent worsening of scoliosis 4. SLT 5. Behavioural therapy