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Genetics > Lecture 4: Neurodegenerative Disease and Neurofibromatosis > Flashcards

Lecture 4: Neurodegenerative Disease and Neurofibromatosis Flashcards

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Biology 101 flashcards
1
Q

Neurodegenerative Disorders (3)

A
  1. Alzheimer’s Disease
  2. Huntington’s disease
  3. Neurofibromatosis
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2
Q

Alzheimer’s Disease Overview (3)

A
  1. Most common form of dementia in older people
  2. usually begins after age 60 and risk increased with age
  3. progressive impairment of intellectual function, loss of memory, insight, judgement, abstraction, and language
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3
Q

Alzheimer’s Disease Mechanism (4)

A
  1. Normal communication between nerve cells is blocked
  2. loss of cholinergic neurons
  3. formation of plaque and tangles
  4. brain atrophy
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4
Q

Risk Factors of Alzheimer’s Disease (7)

A
  1. Aging
  2. Family hx of dementia
  3. lower educational level
  4. female gender
  5. hx of head injuries
  6. depression
  7. hypertension
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5
Q

Familial Alzheimer’s Disease

A
  1. “early onset” symptoms start before age 65

2. autosomal dominant

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6
Q

Familial Alzheimer’s Contributing Gene Mutations (3)

A
  1. Amyloid Precursor Protein (APP)
  2. Presenilin 1
  3. Presenilin 2
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7
Q

Amyloid Precursor Protein

A
  1. integral membrane protein-function unclear
  2. improper cleavage of APP generates beta amyloid component of amyloid plaques
    * contributor to Familial Alzheimers
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8
Q

Presenilin 1 & 2

A
  1. sub-components of an enzyme involved in processing APP

* contributors to Familial Alzheimer’s

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9
Q

Amyloid-beta (3)

A
  1. AD pathogenesis is triggered by accumulation of Amyloid-beta
    - due to overproduction and/or failure of clearance mechanisms
  2. Amyloid-beta aggregates into oligomers, which can be of various sizes, and forms diffuse and neuritic plaques in the parenchyma of blood vessles
    - amyloid antipathy
  3. Amyloid-beta oligomers and plaques block proteasome function, inhibit mitochondrial activity, alter intracellular Ca2+ levels and stimulate inflammatory processes
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10
Q

Sporadic Alzheimer’s Disease (4)

A
  1. late onset, developed after age 65
  2. APOE gene found on chromosome 19
  3. AD risk increases with presence of one or two copies of APOE e4 allele
  4. incomplete penetrance of APOE e4
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11
Q

Normal function of ApoE protein (3)

A
  1. transports lipoproteins, fat soluble vitamins and cholesterol in blood and lymph system
  2. shown to enhance proteolytic breakdown of beta amyloid
  3. e4 allele not as affective in breakdown of beta amyloid
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12
Q

Neurofibrillary Tangles

A
  1. Form in Neurons of AD patients

2. abnormal collections of twisted threads formed by a protein (tau) that is hyperphosphorylated

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13
Q

Tau proteins and their mechanism in AD (3)

A
  1. bind and help stabilize microtubules
  2. altered in AD, changed chemically
  3. altered TAU twists into paired helical filaments-2 threads of tau wound around each other
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14
Q

Hyperphosphorylated tau and its mechanism in AD (4)

A
  1. in helical filaments
  2. insoluble
  3. disrupts microtubule function
  4. leads to cell death
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15
Q

Early Presentation AD

Diagnostic Clues (2)

A
  1. memory problems

2. visuospatial abilities

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16
Q

Later findings AD

Diagnostic clues (3)

A
  1. personality changes
  2. behavioral difficulties
  3. hallucinations
17
Q

End-stage AD

Diagnostic clues (5)

A
  1. Near-mutism
  2. inability to sit up, hold head, track object with eyes
  3. difficulty with eating and swallowing, weight loss
  4. bowel or bladder incontinence
  5. recurrent respiratory or urinary tract infections
18
Q

Huntington Disease overview (3)

A
  1. AKA Huntington’s Chorea
  2. Carriers for HD are almost always asymptomatic in childhood and adolescence
  3. age of onset is typically between 30-50 years
    - Peak around 45 years
    - rarely manifests before age 20
19
Q

Characteristics of Huntingon’s Disease (5)

A
  1. autosomal dominant d/o characterized by involuntary movements of the body
  2. deterioration of cognitive function
  3. severe emotional disturbance
  4. mircoscopic deposits of amyloid-related protein in the basal ganglia
  5. onset of sx to death averages 15 years
20
Q

Genetics of HD (5)

A
  1. most prevalent in white people of northwestern european ancestry
  2. most inherited- some due to spontaneous mutations
  3. mutation of HD gene on chromosome 4 codes for Huntington protein
  4. Appears to be only human d/o of complete dominance-manifestations of the disease does not significantly differ for homozygous and heterozygous carriers
  5. sex of affected parent exerts strong influence on expression of HD
    - inheritance from father-clinical disease 3 years earlier than inheritance from mother
21
Q

Genetics HD pt. II (5)

A
  1. expansion of poylglutamine sequence (CAG)n in the HTT gene on chromosome 4p16.3 which codes for huntington protein*
  2. 10-35 CAG repeats have no disease risk
  3. 36-39 repeats may or may not develop symptoms of Huntington disease (incomplete penetrance)
  4. beginning with 40 CAG repeats, all affected individuals will develop huntington dieseae
  5. inverse correlation between the number of repeats and the age of onset of the disease
    - higher the number of repeats, the earlier the onset
22
Q

HTT Anticipation (2)

A
  1. size of CAG trinucleotide repeat often increased in size from one generation to the next
  2. larger number of repeats is usually associated with earlier onset of signs and symptoms
23
Q

Diagnostic clues of HD

Early changes

A

Behavioral

  1. irritability
  2. moodiness
  3. antisocial behavior
  4. psychiatric disturbance
  5. mild dyskinesia
24
Q

Diagnostic clues of HD

Later signs and symptoms (4)

A
  1. choreiform movements
  2. dystonic posturing
  3. severe balance and coordination problems
  4. progressive dementia
25
Q

Diagnostic Testing HD (4)

A
  1. through family hx and medical hx
  2. CT scan in established cases
    - cerebral atrophy
    - atrophy caudate nucleus
  3. MRI and PET scans
    - reduced glucose utilization in an anatomically normal caudate nucleus
  4. Genetic testing and counseling for children od HD -affected parents
26
Q

Treatment HD (5)

A
  1. symptomatic relief
    - no cure or treatment to slow disease progression
  2. Dopamine receptor blockers
    - -may control dyskinesia and behavioral disturbance
  3. Speech therapy
  4. Physical therapy
  5. occupational therapy
27
Q

Neurofibroma (4)

A
  1. benign, encapsulated tumor
  2. proliferations of schwann cells that are of ectodermal (neural crest) origin
    - form continuous envelope around each nerve fiber or peripheral nerves
  3. autosomal dominant genetic d/o
  4. tumors grow on the coverings of nerves anywhere in body at any time
  5. 1:3,000-4,000 males and females of all races and ethnic groups worldwide and is the most common genetic d/o in U.S.
28
Q

NF 1 (5)*

A

Neurofibromatosis type 1
“Von Reckling

  1. neurofibromas, neurofibromas-saromas
  2. optic nerve gliomas
  3. pigmented cutaneous macule (cafe au lait)
  4. pigmented nodules of iris (lisch nodules)
  5. caused by mutation in NF1 gene (chromosome 17, encodes for neurofibromin)
29
Q

NF2 (3)*

A

Neurofibromatosis type 2

  1. bilateral schwannomas of CN VIII
  2. multiple meningiomas
  3. spinal cord ependymomas
30
Q

NF basic characterization

A
  1. Variant characterized by the development of noncancerous tumors called schwannomas on nerves that control hearing and balance
    - auditory and vestibular nerves
31
Q

Genetics-NF1

A
  1. inherited in an autosomal dominant pattern
  2. 50% of those affected by this disease have a prior family hx of NF
    - other 50% appear to be the first members of their family to have d/o
32
Q

Chromosome 17

A

codes for neurofibromin

-mutation fond here in NF1

33
Q

Neurofibromin

A

intracellular signaling molecule of RadGAP (Rad GTPas activating protein) signal cascade

34
Q

Function of normal NF1 gene

A

tumor suppressor gene

-loss of tumor suppressor in NF1 allows neurofibromas to form

35
Q

Genetics NF-2

A
  1. inherited autosomal dominant pattern caused by mutation in NF2 gene that encodes merlin
36
Q

NF2 gene encodes

A

merlin

37
Q

merlin

A

tumor suppressor gene and mutation leads to formation of shwannomas

Genetics (14 decks)

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