Muscular dystrophies

Question 1

DMD

Answer 1

X-linked recessive

Question 2

Becker

Answer 2

X-linked recessive

Question 3

Limb girdle MD

Answer 3

Autosomal recessive

Question 4

Fascioscapular humeral

Answer 4

Dominant

Question 5

Scapulohumeral

Answer 5

Autosomal recessive

Question 6

Occulopharyngeal

Answer 6

Dominant

Question 7

Myotonic dystrophy

Answer 7

Dominant (face, resp, limbs)

Question 8

Muscle weakness, myotonia, non-muscle features

Autosomal dominant – Ch19 and Ch3

Adolescence – face, distal limbs

Later – respiratory muscles

Answer 8

Myotonic dystrophy (type 1 and type 2)

Question 9

Mutations in dystrophin gene on long arm chromosome X

Alterations in anchorage of actin cytoskeleton to basement membrane

Fibres liable to tearing

Uncontrolled Ca2+ entry into cells

Answer 9

DMD

-alteration in achorage of actin cytoskeleton to basement membrane

Question 10

Atrophy of type 1 fibres

Central nuclei

Ring fibres

Fibre necrosis

Fibrofatty replacement

Answer 10

Myotonic dystrophy

Question 11

Muscle fibre necrosis & phagocytosis
Regeneration
Chronic inflammation and fibrosis
Hypertrophy

Answer 11

DMD

Question 12

Endomysial lymphocytic infiltrate, invasion of muscle by CD8 + T lymphocytes

Segmental fibre necrosis

Answer 12

Polymyositis

Question 13

Immune complex and complement deposition within and around capillaries within muscle

Perifascicular muscle fibre injury

B-lymphocytes and CD4 + T cells > cf polymyositis

Answer 13

Dermatomyositis

Question 14

Neurogenic disorders of muscle

Answer 14

Small, angulated muscle fibres (adults)
Small, round muscle fibres (infants)
Target fibres
Fibre type grouping
Grouped atrophy

Question 15

Progressive degeneration of anterior horn cells

Denervation atrophy, fasciculation and weakness

Answer 15

Motor neuron disease

Question 16

Inherited; autosomal recessive – Ch5

Degeneration of anterior horn cells in spinal cord

Denervation of muscle

Types 1 - 4

Answer 16

Spinal muscular atrophy

Question 17

Biopsy; fibrinoid necrosis of vessels

Serum contains pANCA (perinuclear antineutrophil cytoplasmic autoantibody)

Answer 17

PAN

Question 18

Death in scleroderma?

Answer 18

Renal failure secondary to malignant hypertension
Severe respiratory compromise
Cor pulmonale
Cardiac failure or arrhythmias secondary to myocardial fibrosis