Muscular Dystrophies

Question 1

Calf pseudohypertrophy?

Answer 1

Muscular dystrophy (most commonly Duchenne

Question 2

Child uses arms to stand up from squat?

Answer 2

Gowers sign (Duchenne muscular dystrophy)

Question 3

Pathogenesis of Duchenne Muscular Dystrophy?

Answer 3

Spontaneous Frame shift => Deletion or insertion of a number of nucleotides not divisible by 3=> misreading=> truncated, nonfunctional protein=> inhibited muscle regeneration

Question 4

Dystrophin gene has increased chance of spontaneous mutation why?

Answer 4

DMD is Dystrophin gene (DMD) is the largest

protein-coding human gene

Question 5

What does Dystrophin do?

Answer 5

Connects intracellular (actin) to the transmembrane proteins α- and β-dystroglycan=> helps anchors muscle fibers

Question 6

Dystophin helps anchor which two muscle fibers?

Answer 6

Skeletal and Cardiac

Question 7

MCC of death?

Answer 7

Dilated Cardiomyopathy

Question 8

Genetics of duchenne? Female carriers of this disease variably affected depending on the percentage of?

Answer 8

X linked

Inactivation of the X chromosome

Question 9

Another term for inactivation of the X chromosome?

Answer 9

Lyonization

Question 10

What is the difference between Duchenne’s and Becker’s? Why is Becker more mild?

Answer 10

Non-frame frameshift mutation=> partially functional disorder

Question 11

Fragile X is a disorder due to?

Answer 11

X-Linked Defect on FMR1 Gene=>everything is large