Flashcards in Neurogenetics Deck (14):
Duchenne muscular dystrophy:
sporadic in 1/3
What is duchenne muscular dystrophy?
Muscular dystrophies are a group of inherited conditions with an intrinsic defect of muscle.
They are characterized by progressive wasting and weakness
DMD is where the pelvic/shoulder girdle muscles are affected
What are the s/s of duchenne muscular dystrophy?
Delay in motor development
Onset of weakness ~ 3-4 years
pelvic and shoulder girdles
Wheelchair bound by 10-12 years
Death from involvement of respiratory and cardiac muscles in 20s
What is the genetic mutation is duchenne muscular dystrophy?
What is the diagnosis of duchenne muscular dystrophy?
developmental delay in boys
raised serum creatine kinase (CK)
-CK is a vague marker for muscle disease but in context of other signs/symptoms useful
Electromyography (EMG) – characteristic electrical signs
muscle biopsy – can back up the genetic test
molecular genetic testing
- screen for deletions
Describe the carrier testing for duchenne muscular dystrophy
identify mutation in affected boy
test for mutation in female relatives wishing to know carrier status
female carriers of known dystrophin mutations can be offered prenatal testing
What is beckers muscular dystrophy?
milder form of duchenne muscular dystrophy:
-Later onset (teens and early twenties)
-Mutation in dystrophin
Huntingdons disease - inheritance?
autosomal dominant chromosome 4
What is huntingdons disease
Progressive neurodegenerative disorder
Onset usually between 30 and 50 years
Progression to severe dependency and deathover 15-20 years
What are the early clinical signs of huntingdons disease?
Abnormal eye movements
What are the late clinical signs of huntingdons disease?
Trouble with balance and walking
Trouble with activities that require manual dexterity
Slow voluntary movements
Difficulty initiating movement
Inability to control speed and force of movement
What are the end stage clinical signs of huntingdons disease?
Bradykinesia (difficulty initiating and continuing movements)
Severe chorea (less common)
Serious weight loss
Inability to walk
Inability to speak
Swallowing problems, danger of choking
Inability to care for oneself
What is the pathogenesis of huntingdons disease?
Condition is characterised by loss of neurons in basal ganglia and especially the caudate nucleus
-caused by more than 36 CAG repeats in the huntingdon gene
-this displays penetrance (as it gets passed down, the younger those are affected)