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Flashcards in Neurogenetics Deck (22)
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1
Q

What is the inheritance pattern in DMD?

A

x-linked recessive

however it is caused by new mutations in 1 in 3 boys

2
Q

What is the genetic defect in DMD?

A

large scale deletion of dystrophin gene in 70%

point mutations, small insertions and deletions in remaining 30%

3
Q

What is the inheritance pattern in Huntington’s disease?

A

autosomal dominant

4
Q

Describe the penetrance seen in HD and what this means.

A

age dependent penetrance (variable)

chance seems to decrease with age

5
Q

What is the normal Huntingtin gene vs pathogenic variant?

A

CAG-20
vs
CAG-42

6
Q

What does CAG code for?

A

glutamine

7
Q

Which condition involves loss of anterior horn cells in the spinal cord and brain stem nuclei?

A

spinal muscular atrophy

8
Q

Inheritance pattern of spinal muscular atrophy

A

autosomal recessive

9
Q

A deletion on chromosome 5 would result in which type of spinal muscular atrophy?

A

SMN1 deficiency

10
Q

What is the difference between SMN1 and SMN2? What does this mean for treatment?

A

SMN2 is identical to SMN1 mRNA but exon 7 is spliced out

this means that SMN1 deficiency can be corrected by altering the spicing of SMN2 mRNA

11
Q

List some of the possible mutations seen in early onset Alzheimer’s disease.

A

Early onset = autosomal dominant
APP mutations - chromosome 21
presenilin 1 - chromosome 14
presenilin 2 - chromsome 1

12
Q

Which polymorphic apolipoprotein predisposes to alzheimer’s with some clustering in families?

A

Apo e4

13
Q

Which apolipoprotein has the highest frequency seen in AD?

A

Apo e3 (72%)

14
Q

Which apolipoprotein is associated with longevity?

A

Apo e2

15
Q

Which mutation is commoner in alzheimer’s - autosomal dominant or multifactorial forms?

A

commoner –> multifactorial forms

rare AD forms

16
Q

T/F: patients with no apolipoprotein e4 genotype are most likely to acquire Alzheimer’s.

A

false: no e4 –> 9% affected by 85

17
Q

The genotype for Alzheimer’s with highest penetrance is e4/e4 - T/F?

A

true

55% affected by 80

18
Q

Describe the damage to spinal cord in DMD.

A

there is no damage to spinal cord or nerves

19
Q

Which muscle component is destroyed in DMD?

A

sarcolemma

20
Q

Patient presents with gradually progressive hypotonia, proximal muscle weakness and tongue fasciculations. Ddx?

A

spinal muscular atrophy (progressive loss of anterior horn cells)

21
Q

What is the APP gene and where is it found?

A

amyloid precursor protein found on chromosome 21

22
Q

what is amyloid beta protein and where is it found?

A

a fragment of the APP gene, found in deposits in senile plaques in Alzheimer’s disease