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Neurology > CD: DS and FX > Flashcards

CD: DS and FX Flashcards

1
Q

What is DS? (2)

A
  1. Chromosomal disorder caused by an extra chromosome 21

2. Results in intellectual disability and physical abnormalities

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2
Q

What is the incidence of DS?

A

1/700 live births

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3
Q

What is the link between maternal age and DS? (4)

A
  1. Majority are born to women over 35 years (80%)
  2. 20 years: 1/2000
  3. 35: 1/365
  4. 40: 1/100
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4
Q

What is the aetiology of DS?

A
  1. 95% = extra chromosome (47), typically maternally derived

2. 5% = typical 46 chromosomes but extra chromosome 21 translocated to another chromosome

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5
Q

What is the most common translocation in DS?

A

t(14;21), then (21;22)

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6
Q

Summarise the impact of DS (5)

A
  1. Characteristic phenotype
  2. Delayed growth and development
  3. Intellectual disability
  4. Cardiac manifestations (50%)
  5. Gastro-intestinal manifestations (5%)
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7
Q

Describe the characteristics of a newborn with DS (2)

A
  1. Placid, rarely cry

2. Hypotonia

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8
Q

Describe the physical appearance of DS (7)

A
  1. Flat facial profile
  2. Small head and face
  3. Sometimes tongue is large
  4. Extra skin around back of the neck
  5. Ears are small, rounded and low-set
  6. Hands = short and broad, single palm cream
  7. Short in height
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9
Q

Describe the growth and development in DS (3)

A
  1. Mean IQ = 50 (average 100)
  2. Delay of physical and intellectual development
  3. Increased incidence of autism and ADHD
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10
Q

How is DS diagnosed before birth? (3)

A
  1. Ultrasonography
  2. Blood tests of mother
  3. Diagnosis confirmed via chorionic villus sampling, amniocentesis with karotype analysis or chromosomal microarray analysis
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11
Q

How is DS diagnosed after birth? (3)

A
  1. Appearance
  2. Blood tests
  3. Karotyping
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12
Q

What is the intervention for DS? (3)

A
  1. Regular monitoring: ECG, thyroid screening, hearing evaluations, opthalmology, growth, obstructive sleep apnea
  2. Treatment of specific symptoms
  3. Genetic counselling
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13
Q

What is the prognosis of DS? (3)

A
  1. Better compared to other extra chromosomal disorders eg. Trisomy 18
  2. Ageing process accelerated
  3. Most survive to adulthood
  4. Increased risk of Alzheimer’s
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14
Q

What is the average life expectancy in DS?

A

55 years but some live until 70/80s

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15
Q

What reduces the life expectancy in DS? (3)

A
  1. Heart disease
  2. Increased susceptibility to infections
  3. Leukaemia
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16
Q

Give 2 examples of specific symptoms treated in DS

A
  1. Congenital cardiac anomalies are repaired surgically

2. Hypothyroidism is treated with thyroid hormone support

17
Q

What is Fragile X?

A
  1. Genetic abnormality on the X chromosome

2. Leads to intellectual disability and behavioural disorders

18
Q

What is the prevalence of fragile X?

A
  1. Boys (1/4000) girls (1/8000)
  2. Girls typically less impaired
  3. Most commonly diagnosed inherited caused of intellectual disability
19
Q

Summarise the inheritance pattern of fragile X (3)

A
  1. X-linked dominant pattern
  2. Males: mutation in the only copy of a gene in each cell causes the disorder
  3. Females: mutation in one of the two copies causes the disorder
20
Q

What is a premutation that women can have? (3)

A
  1. FMRI gene premutation on the X chromosome can expand to more than 200 CGG repeats in cells that develop into eggs
  2. Increased risk of having a child with fragile X syndrome
  3. Men pass premutation only to daughters, sons receive a Y chromosome which does not contain FMR1 gene
21
Q

What is the aetiology of Fragile X? (2)

A
  1. Abnormality of FMR1 gene on the X chromsome
  2. People with 55 to 200 extra copies are considered to have a premutation (don’t have disorder but offspring have greater risk)
22
Q

Summarise the characteristics of Fragile X (5)

A
  1. Physical features
  2. Intellectual disability
  3. Hyper-extensible joints
  4. Heart disease
  5. Premature ovarian failure (women with premature ovarian failure, menopause in mid 30s)
23
Q

What are the physical features of Fragile X? (4)

A
  1. Large, protuberant ears
  2. Prominent chin and forehead
  3. High arched palate
  4. Macroorchidism (abnormally large testes in post-pubertal male)
24
Q

What are the cognitive abnormalities which may occur in Fragile X? (2)

A
  1. Mild-moderate intellectual disability

2. ASD features

25
Q

How is Fragile X diagnosed? (3)

A
  1. DNA testing
  2. Frequently not suspected until adolescence (depending on symptom severity)
  3. Boys with ASD and intellectual disability should be tested for Fragile X
26
Q

How is Fragile X treated?

A
  1. SLTs, OTs

2. Medication: stimulants, anti-depressants, anti-anxiety

Neurology (17 decks)

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