CNS Genetics

Question 1

What type of inheritance is involved in DMD?

Answer 1

X linked recessive inheritance

Question 2

What are the features of DMD?

Answer 2

Delay in motor development
proximal girdle weakness at 3-4 years
wheelchair by 10-12 years

Question 3

What age do DMD patients commonly die?

Answer 3

20s

Question 4

What ultimately causes death in DMD patients?

Answer 4

involvement of respiratory and cardiac musculature

Question 5

What happens to the calves in DMD/BMD patients and why?

Answer 5

Pseudohypertrophy - muscle tissue is replaced with bulky scar tissue - a sign of strength that is actually a sign of weakness

Question 6

What is the deficiency in DMD?

Answer 6

deficiency of dystrophin

Question 7

What is gower’s sign?

Answer 7

Using hands etc to push oneself up as muscle weakness makes it difficult

Question 8

How is DMD diagnosed?

Answer 8

raised CK
EMG
muscle biopsy
molecular genetic testing

Question 9

What testing can be offered to women around pregnancy who know they carry a dystrophin gene?

Answer 9

prenatal/pregestational testing

Question 10

What is Becker’s Muscular Dystrophy?

Answer 10

a less severe form of muscular dystrophy - 1/18000, patients live into their 40s

Question 11

What is the inheritance pattern of Huntington’s disease?

Answer 11

Autosomal dominant

Question 12

What age is the onset of HD usually apparent?

Answer 12

30-50s

Question 13

What are the common features of HD?

Answer 13

involuntary movements
dementia
progression to severe dependancy and death over 15-20 years

Question 14

What protein does CAG code for?

Answer 14

glutamine?

Question 15

What codon repeat is seen in HD?

Answer 15

CAG repeats

Question 16

What is the significance of the repeats of CAG?

Answer 16

increased repeats can mean younger onset of disease

Question 17

What is the cure for HD?

Answer 17

There isn’t one!

Question 18

What form of testing is offered to mothers around pregnancy who are known HD sufferers

Answer 18

prenatal/pre-gestational testing

Question 19

What is the commonest cause of dementia?

Answer 19

Alzheimer’s Disease

Question 20

Is there a genetic link in AD?

Answer 20

yes

Question 21

What is the pathophysiology of AD?

Answer 21

loss of cortical neurones 
neurofibrillary tangles (intracellular)
Senile Plaques (extracellular)

Question 22

What material makes up senile plaques?

Answer 22

B-amyloid

Question 23

What material makes up neurofibrillary tangles?

Answer 23

Tau

Question 24

What is the significance of apolipoprotein E4?

Answer 24

predisposes to AD with some clustering in families

Question 25

What is the significance of apolipoprotein E2?

Answer 25

associated with longevity

Question 26

What type of inheritance is MS?

Answer 26

multifactorial - multiple factors contributing a little to risk