Muscular Dystrophy

Question 1

muscular dystrophy

Answer 1

• degen of skeletal muscles (unrelated to aging)
• progressive
• atrophy, necrosis & pseudohypertrophy
• several different types

Question 2

Duchenne MD

Answer 2

• 1 in 3500 males
• age of onset: at birth (genetic/congenital)
• MOI: X-linked recessive (more common in males)
• mutated dystrophin gene on short arm of X-Chr
• pseudohypertrophy

Question 3

mutated dystrophin gene on short arm of X-Chr patho

Answer 3

Mutated gene –> dec dystrophin Fx –> improper attachment of contractile filaments –> fibre necrosis w/ use –> poor repair & regen –> more necrosis (muscle fiber cells die) –> Ca+ influx (sarcolemma’s selective permb altered) & Es released when cells die (ex. CK – creatine kinase)

Question 4

dystrophin gene Fx

Answer 4

Attaches contractile filaments to e/o, to sarcolemma & matrix of fiber

Question 5

pseudohypertrophy

Answer 5

Contractile fibres lost & connective tissue deposited where muscle cells were –> fibrofatty CT replaces muscle

Question 6

mnfts

Answer 6

• asympt until 2-3 yrs
• progressive muscle weakness & skeletal pain
• skeletal muscles affected primarily, but as disease progresses, cardiac muscle affected too
• death from resp/cardiac cmplx

Question 7

Dx

Answer 7

• Hx, Px (onset 2-3 yrs)
• biopsy (reveal histologic problems in muscles)
• blood sample (serum creatine kinase)
• prenatal Dx
• carrier (test if mother carries mutated gene)

Question 8

Tx

Answer 8

• supportive & symptom management (no cure)

- inc comfort & Fx (ex. breathing exercises, braces for support)