Disorders of muscle

Question 1

dystrophin

Answer 1

connects actin to sarcolemma

Question 2

Name 3 inflammatory myopathies. Tx? Which involves skin?

Answer 2

dermatomyosits (skin), polymyositis, inclusion body myositis. DM and PM get steroid tx. IBM doesnt respond.

Question 3

PM vs Dm: cells involved? Atrophy? Patterns?

Answer 3

T cells vs B cells. Endomysial vs perimysial (with perifascicular atrophy). Both patterns are proximal and symmetric

Question 4

IBM: pattern

Answer 4

wrist flexors and knee extensors

Question 5

Duchenne muscular dystrophy: genetics, progression, lab findings, tx

Answer 5

dystrophin gene, X-linked recessive. Normal at birth, wheelchair by 12, dead in 20’s. Elevated CK. Prednison

Question 6

Becker MD:

Answer 6

milder than DMD. Dystrophin is semifunctional.

Question 7

mechanism of atrophy in DMD and BMD

Answer 7

lack of quality dystrophin. Membrane tears on contraction. necrosis. replaced with CT and fat

Question 8

Myotonic dystrophy: what is it? genetics? defect? pattern?

Answer 8

delated relaxation of SKM following contraction. CTG expansion. Cl channel abnormalities resulting in sarcolemmal excitability changes. Distal mm first. Weak facial mm.

Question 9

Pomp Disease: deficiency, result, tx

Answer 9

acid alpha-glucosidase deficiency. glycogen accumulation in lysosomes. tissue distruction. enzyme replacement

Question 10

McArdle Dz: deficiency? labs? related phenomena

Answer 10

myophosphorylase deficiency. Impaired glycolysis. myoglobinuria. second wind phenomenon due to glucose mobilization

Question 11

carnitine deficiency

Answer 11

impaired transport of FAs into mitochondria therefore no lipid metabolism.

Question 12

Statin myopathy: signs and labs. Mechansim

Answer 12

CK elevation, myalgia, weakness, myoglobinuria. Stains inhibit HMG-CoA reductase and geranylgeraniol which is necessary for coQ10 which is necessary for ATP production. Also decreased cholesterol in mm membranes.