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GEN 602 > Adult Conditions > Flashcards

Adult Conditions Flashcards

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1
Q

what are the main characteristics of CMT? how common?

A

chronic moto and sensory neuropathy?

1:2500

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2
Q

what are the major features of CMT?

A

childhood-adulthood onset

slow progression

clinical findings: distal muscle weakness/atrophy (progresses from legs to arms); distal sensory loss

less common: pain, SNHL

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3
Q

what are the genes most commonly associated with CMT? more often inherited or de novo?

A

PMP22 duplication

GDAP1, GJB1, HINT1, MFN2, MPZ, SH3TC2, SORD

more often inherited (AR, AD, XL)

some reduced penetrance

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4
Q

what the traditional classifications of CMT? how are these classified?

A

demyelinating

axonal/non-demyelinating

dominant intermediate CMT

NCV rate

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5
Q

how is CMT dx?

A

clinical: peripheral neuropathy on exam (MNCV and EMG)

FHx

genetics: single gene for PMP22 w/ del/dup -> multigene panel, ES/GS

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6
Q

what is prognosis for those with CMT?

A

not life-limiting

difficult to predict

progression can result in disability

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7
Q

what is CADASIL? how is it characterized? gene?

A

hereditary multi-infarct dementia

recurrent strokes, cognitive decline, migraine w/ aura, psychiatric disturbances

other: epilepsy, other body systems may be invovled

mid-adulthood onset

NOTCH3

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8
Q

what findings are suggestive of CADASIL?

A

recurrent strokes and TIA, executive dysfunction, migraine with aura, mood disturbances and apathy, brain imaging, FHx

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9
Q

what testing strategy would you employ is you suspected CADASIL?

A

NOTCH3 seq w/ del/dup

epilepsy, leukodystrophy and leukoencephalopathy panels, ES, known familial variant

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10
Q

what is the prognosis for someone with CADASIL?

A

symptoms usually progress slowly

some lose ability to walk due to strokes

life expectancy significantly shortened in AMAB individuals

most common cause of death is pneumonia

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11
Q

what % of newly dx prion disease is genetic?

A

about 15%

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12
Q

what gene is associated with genetic prion disease?

A

PRNP

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13
Q

what are some general characteristics of prion diseases?

A

cognitive difficulty, ataxia, myoclonus, other findings

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14
Q

If phenotypes overlap, why is it important to determine type of prion disease?

A

can inform disease course

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15
Q

what % of CJD is genetic? how does it compare to sporadic CJD?

survival?

A

10-15%

earlier onset and longer duration compared to sporadic

median survival following onset is 6mo (can be up to 2 years)

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16
Q

what is the mean age of onset for GSS? disease duration?

A

52.5y -> 60mo duration

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17
Q

when do signs begin to appear for GSS?

A

4th to 6th decade of life

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18
Q

what proteins in CSF can point to genetic prion disease?

A

14-3-3 and tau

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19
Q

what clinical findings can indicate genetic prion disease?

Study These Flashcards
A

dementia followed by ataxia, myoclonus, and extrapyramidal/pyramidal involvement

20
Q

how is someone dx with a genetic prion disease (CJD or GSS)?

Study These Flashcards
A

suggestive findings AND PRNP variant

21
Q

what are the common mutations for gCJD? GSS? what is the risk codon?

Study These Flashcards
A

CJD: D178N, E200K, V180I, V210I

GSS: P102L

risk: SNP at 129 - Val or Met**

those homozygous for Met at 129 have been shown to ave earlier onset and more rapid progression

22
Q

how many probands with gPrD will not have a FHx?

how effective is single gene testing?

Study These Flashcards
A

up to 60%

seq w/ del/dup of PRNP detects almost all pathogenic variants

23
Q

what causes the features of Huntington disease?

Study These Flashcards
A

death of neurons in the brain beginning in the basal ganglia (movement coordination) and spreading into frontal lobe (higher thinking

24
Q

what are the motor features seen with HD? cognitive? psychiatric?

Study These Flashcards
A

motor: chorea, athetosis, rigidity, bradykinesia, akinesia -> generally involuntary or difficulty with voluntary movement (impacts entire body)
cognitive: forgetfulness, slowness of thought, impaired visiospatial ability, impaired planning and judgement
psychiatric: personality changes, psychosis, depression, irritability

25
what the expected progression of HD?
median survival is 15-18yrs after onset may start as clumsiness or forgetfulness
26
what causes HD? what are the genotype/phenotype correlations?
trinucleotide repeat expansion (CAG) in HTT gene (4p16.3) 36-55 repeats: adult onset 60+ repeats: juvenile onset
27
what repeats can modify HD development/onset?
CAA interruptions no interruptions -> younger age of onset and increased somatic instability
28
is there expansion seen in HD families?
yes
29
when testing for HD, how you classified with 27-35 CAG repeats? 36-39? 40+? how do we test for these repeats?
27-35: intermediate (may have subtle symptoms but won't develop HD) 36-39: pathogenic but low penetrance 40+: pathogenic and fully penetrant PCR
30
is genetic testing necessary for a HD dx?
can be made with clinical features, but testing is helpful for confirmation and characterizing the # of repeats
31
how would you describe spinocerebellar ataxia type 3?
disorder of brain function and is characterized by increasing problems with coordination
32
what are some of the signs and symptoms of SCA3?
peripheral neuropathy, slow/staggering gait, dystonia, parkinsonism, ophthalmoplegia, exopthalmia, dysarthria, dysphagia, abn pulmonary function, sleep problems associated with restless leg syndrome, etc.
33
what is the prognosis for someone dx with SCA3?
onset typically occurs btwn 20-50y (avg. 36y) life expectancy ranges from mid30s to typical progressive disease
34
what causes SCA3?
ATXN3 gene (14q32.12) produces protein ataxin-3 enzyme -> incorrect folding causes aggregation in nucleus and most severely affects neurons
35
what repeat is associated with SCA3? #s
CAG 12-43: normal 44-60: intermediate 60-87: pathogenic/fully penetrant
36
how can we test for SCA3?
PCR and Southern blot
37
how would you describe early onset familial alzheimer's disease (EOFAD)? symptoms?
subtle/slow progression of memory failure that becomes more severe and eventually incapacitating confusion, anxiety, poor judgement, agitation, speech challenges
38
what genes are associated with EOFAD? complete vs. incomplete penetrance?
APP and PSEN1: complete PSEN2: incomplete
39
what is the typical age of onset with EOFAD?
40s-50s, less than 5% of AD is early onset
40
what proportion of EOFAD is associated with which gene?
APP (10-15%) PSEN1 (20-70%) PSEN2 (5%)
41
what features in FHx may make us suspect EOFAD?
early-onset dementia (at least 3 affected individuals) and age of onset **negative FHx cannot be assumed unless GT has been conducted because young deaths and smaller**
42
what's the prognosis?
typically individuals affected by AD live 8-10y after appearance of symptoms
43
how might we test for EOFAD?
panel with APP, PSEN1/2 and APOE -> ES/GS if negative with unclear single gene-testing not recommended
44
what is the gen pop risk for developing AD? w/ FDR? FHx indicative of EOFAD?
10-12% 20-25%/2-3x baseline assume affected parent: 50%
45
how do APOE e_ alleles impact chances of developing AD?
homozygous XX w/ e4: 40-45% homozygous XY w/ e4: 25-30% hetero e3/e4 alleles: 15-25% e2 allele seems to be a protective factor

GEN 602 (12 decks)

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