Genetics of CNS disease Flashcards

1
Q

What is the inheritance of duchenne’s muscular dystrophy?

A

x-linked recessive

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2
Q

What is the inheritance of Huntingtons disease?

A

autosomal dominant

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3
Q

At what age does weakness tend to begin with DMD?

A

3-4years

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4
Q

Where does weakness in DMD usually begin?

A

pelvic and pectoral gigrdles

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5
Q

What is the characteristic posture of a boy with DMD?

A

accentuated lumbar lordosis

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6
Q

What is typically seen in the legs of patients with DMD?

A

calf hypertrophy

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7
Q

What causes DMD?

A

deficiency of dystrophin

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8
Q

What is the function of dystrophin?

A

connects contractile elements eg actin in muscle cell to proteins in the cell membrane

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9
Q

What is the difference between DMD and BMD?

A

duchennes dont have dystrophin at all whereas BMD have a shortened version of the protein

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10
Q

What is the most common genetic mutation in DMD?

A

large scale deletion of dystrophin gene in 70%

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11
Q

Why is toe walking seen in patients with DMD?

A

shortening of their achilles tendon

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12
Q

What are the investigations done fro DMD?

A

CK; EMG; muscle biopsy; genetic testiing

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13
Q

When is the typical onset of Huntington’s?

A

between 30 and 50

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14
Q

What are the early signs of Huntington’s?

A

clumsiness; agitation; irritabililty; apathy; anxiety; disinhibtion; delusions; abnormal eye movements; depression

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15
Q

What are the later signs of Huntington’s?

A

dystonia; involuntary movements; slow voluntary movements; weight loss; speech difficulties; stubbornness

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16
Q

What happens to the basal ganglia in Huntington’s?

A

caudate nucleus atrophy (and cerebral cortex)

17
Q

What is the genetic defect in HD?

A

increased CAG repeats

18
Q

What does CAG code for and why does excess repeats cause problems?

A

glutamine- too much is neurotoxic

19
Q

What happens to the Huntington gene as it is passed down?

A

increased exapnsions so decreased age of onset

20
Q

What is the pathology seen in Alzheimers?

A

loss of cortical neurones; protein deposits intracellular- neurofibrillary tangles and extracellular- senile plaques

21
Q

What are senile plaques?

A

extracellular protein deposits containing amyloid beta protein

22
Q

What is amyloid beta protein?

A

a fragment of the product of the amyloid precursor protein from chromosome 21

23
Q

What genetic condition is associated with early onset Alzheimers?

A

Down syndrome

24
Q

What mutations can cause autosomal dominant early onset Alzheimers?

A

APP mutations of chromosome 21; Presenilin 1- chromsoms 14 and Presenilin 2 on chromosome 1

25
Q

Which allele of apolipoprotein E predisposes to Alzheimers?

A

e4

26
Q

What is the concordance of MS in monozygotic twins vs dizygotic twins?

A

25% vs 3%