Myotonic Dystrophy

Question 1

Typically develops at what age?

Answer 1

20-30y

Question 2

What type of muscle is affected in myotonic dystrophy

Answer 2

skeletal
cardiac
smooth muscle

Question 3

Genetic component of myotonic dystrophy (Types 1 and 2)

Answer 3

autosomal dominant
Trinucleotide repeat disorder

DM1 - CTG repeat at the end of the DMPK gene on chromosome 19

DM2 - repeat expansion of the ZNF9 gene on chromosome 3

Question 4

Is distal muscle weakness more common in DM1 or DM2?

Answer 4

DM1 - distal weakness

DM2 - proximal weakness

Question 5

Clinical features of myotonic dystrophy

Answer 5

frontal balding
bilateral ptosis
cataracts
dysarthria
myotonia (tonic muscle spasm)
weakness of arms and legs
mild mental impairment
diabetes mellitus
testicular atrophy
heart block, cardiomyopathy
dysphagia