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3a neurology > Genetic Conditions > Flashcards

Genetic Conditions Flashcards

1
Q

What is Huntington’s disease

A

A genetic condition that causes progressive neurological dysfunction

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2
Q

What is the inheritance pattern of Huntington’s disease

A

autosomal dominant

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3
Q

What causes Huntington’s disease

A

It is a trinucleotide repeat disorder caused by an expanded CAG repeat at the N-terminus of the HTT gene, which codes for the huntingtin protein

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4
Q

What chromosome is the HTT gene located on

A

Chromosome 4

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5
Q

What protein does CAG code for

A

Glutamine

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6
Q

Explain the pathophysiology of Huntington’s disease

A
  • Elongated polyglutamine tail is cleaved and toxic fragments are generated
  • Aggregates form that resist degradation and interfere with a variety of normal cellular function
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7
Q

What is the primary affected brain region in Huntington’s disease

A

Striatum

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8
Q

What is the CAG repeat threshold for Huntington’s disease certainty

A

Individuals with 40 or more CAG repeats are certain to develop Huntington’s disease.

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9
Q

What is the relationship between repeat length and symptom onset in Huntington’s disease

A

The longer the repeat length, the earlier symptoms tend to appear

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10
Q

What does 36-39 CAG repeats in Huntington’s disease testing indicate

A

An intermediate result of 36 to 39 repeats implies that the person may or may not develop symptoms of Huntington’s disease during their lifetime.

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11
Q

What does a result of 29-35 CAG repeats indicate in Huntington’s disease testing?

A

This range represents an expanded CAG repeat that will not cause disease in the patient but could expand enough to cause disease in offspring.

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12
Q

What is considered a normal result range for CAG repeats in Huntington’s disease testing

A

<28 repeats

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13
Q

Huntington’s disease displays genetic anticipation. Describe this

A

The tendency for expansion of the CAG repeat in successive generations puts offspring at risk for earlier onset and increased severity of the disease than their parents.

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14
Q

Give 5 clinical manifestations of Huntington’s disease

A
  • Chorea - involuntary, random movements
  • Personality change - depression, Irritability and impulsivity
  • Cognitive decline
  • Deficit in fine motor coordination
  • impaired tandem walking
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15
Q

Characteristics of juvenile Huntington’s disease

A

Patients with juvenile Huntington’s disease may not have chorea but may present with rigidity or parkinsonian symptoms.

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16
Q

How is Huntington’s diagnosed

A

Diagnoses is clinical and can be confirmed by CAG repeat testing

17
Q

How is Huntington’s disease managed non-pharmacologically

A

There are no Tx options for slowing/ stopping disease progression
* Counselling patient and family
* Advanced directive
* Palliative care and MDT

18
Q

Pharmacological interventions for Huntington’s

A
  • Chorea - 1. tetrabenazine, 2. sulpiride
  • Antidepressants - 1. citalopram, 2. Sertraline
19
Q

Give 3 late manifestations of Huntington’s disease

A
  • Weight loss
  • Dysphagia
  • Falls
20
Q

What is the life expectancy for someone with Huntington’s

A

10-20 years after onset of symptoms

21
Q

What are 2 common causes of death in Huntington’s disease

A
  • Aspiration pneumonia
  • Suicide
22
Q

What is the inheritance pattern of neurofibromatosis

A

autosomal dominant fashion

23
Q

What are the genetic causes of the two types of neurofibromatosis

A
  • NF1 (Neurofibromatosis type 1): Caused by a mutation on chromosome 17; more common.
  • NF2 (Neurofibromatosis type 2): Caused by a mutation on chromosome 22
24
Q

Describe the characteristics of neurofibromatosis 1

A
  • Cafe-au-lait spots (>= 6, 15 mm in diameter)
  • Axillary/groin freckles
  • Peripheral neurofibromas - skin coloured , raised nodules/ papules
  • Iris hamatomas (Lisch nodules) in > 90%, yellow-brown spots on iris
  • Scoliosis
  • Pheochromocytomas
25
Q

What are the features of neurofibromatosis 2

A
  • Bilateral vestibular schwannomas
  • Multiple intracranial schwannomas, mengiomas and ependymomas
  • may have Cafe-au-lait spots
26
Q

Give 3 complications of neurofibromatosis 1

A
  • malignant peripheral nerve sheath tumours
  • GI stromal tumour
  • renal artery stenosis
27
Q
A

3a neurology (16 decks)

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