Duchenne's muscular dystrophy Flashcards Preview

2nd year > Duchenne's muscular dystrophy > Flashcards

Flashcards in Duchenne's muscular dystrophy Deck (29)
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1
Q

what is DMD?

A

severe form of muscular dystrophy
low chance of survival past adolescence
affects skeletal muscles initially and then goes on to affect the heart and diaphragm
inherited condition

2
Q

pattern of inheritance of DMD?

A

x-linked recessive condition

3
Q

what are the causes of DMD?

A

almost entirely passed on by female carriers as affected males do not normally survive to reproduce

4
Q

epidemiology

A

1 in 3500 males

most common of the muscular dystrophies

5
Q

how is DMD diagnosed?

A
positive gower's test 
raised creatinine kinase in serum 
EMG - detects muscle destruction rather than problems with nerve conduction 
genetic testing
muscle biopsy 
LFTs - ALT and AST
6
Q

genetic testing

A

Xp21 defect

7
Q

when is DMD diagnosed?

A

between 5-5.5 years old

8
Q

what are the symptoms of DMD?

A
progressive proximal muscle weakness and wasting - most obvious = thigh 
calf swelling 
swelling of tongue 
developmental delay 
abnormal gait - difficulty standing 
trouble getting up from chairs
unable to walk upstairs
waddling gait
general motor skill deficits 
skeletal deformity 
unable to walk by 10 - need wheelchair 
cardiomyopathy
9
Q

what causes calf swelling?

A

pseudohypertrophy

10
Q

what causes swelling of the tongue?

A

fat replacement of wasted muscle

11
Q

cardiomyopathy in DMD

A

heart enlargement causing dilated cardiomyopathy

12
Q

what are the symptoms of dilated cardiomyopathy?

A

arrhythmia
shortness of breath
fatigue
leg and feet swelling

13
Q

what are the treatments for DMD?

A
corticosteroids 
physiotherapy 
mechanical ventilation at later stages 
physical aids 
occupational therapy 
ataluren 
creatine supplements 
gastrostomy 
ACE inhibitors and beta blockers for cardiomyopathy 
pacemaker
corrective surgery 
trial treatments
stem cell therapy
14
Q

corticosteroids

A

aggressive use sometimes before 10 can convert Duchenne’s to a more Becker’s like prognosis

15
Q

purpose of physio

A

reduces rate of contracture and prolongs the useful life of the muscles

16
Q

physical aids

A

wheelchair
leg braces
crutches

17
Q

ataluren

A

newer drug

for over 5s that can still walk

18
Q

what do creatine supplements do?

A

improve muscle strength

19
Q

what is corrective surgery used for?

A

scoliosis
ptosis
contractures
scapular fixation

20
Q

trial treatment

A

exon skipping

21
Q

what could stem cell therapy do?

A

regenerated damaged muscle tissue

22
Q

pathogenesis

A

mutation on DMD gene causes lack of dystrophin production, without it there is an excessive calcium entry into the cells, resulting in excess oxidative stress within the cells, damaging the sarcolemma and causing cell death

23
Q

what does dystrophin do?

A

part of a structure that connects the cytoskeleton of each muscle fibre to the basal lamina.

24
Q

why does a raised creatine kinase indicate DMD?

A

creatine kinase is found within skeletal muscles, brain tissue and cardiac muscle and so it leaks out when muscle cells are damaged as they are broken open and contents are released into the bloodstream

25
Q

what is the process of genetic testing for DMD?

A
genetic counselling
blood or saliva sample 
check dystrophin gene
CGH array testing 
MLPA testing 
PCR 
southern blot testing 
sanger gene sequencing 
can be done prenatally
26
Q

prenatal genetic testing

A
non-invasive prenatal diagnosis
chorion villus sampling 
amniocentesis
placental biopsy 
foetal blood sampling
27
Q

MLPA

A

multiplex ligation-dependent probe amplification

28
Q

CGH

A

comparative genomic hybridisation

29
Q

genetic testing

A

prenatal if parents are carriers
needed if you are offered genetic test
can be directed to relevant patient support groups
genetic testing is free if you are referred for it by a hospital specialist
discussion about risk, prognosis, consequences, tests available