Congenital Myopathies

Question 1

What are the three most common congenital myopathies?

Answer 1

Central Core Disease, Nemaline (Rod) Myopathy, Central Nuclear Myopathy

Question 2

What type of muscle fibers are congenital myopathies generally restricted to?

Answer 2

Type I fibers

Question 3

A patient presents with congenital hypotonia and proximal muscle weakness. Cytogenetic analysis reveals a mutation on the long arm of chromosome 19 and abnormal ryanodine receptors. What is the Dx? What staining is lost? What potentially fatal complicaiton exists?

Answer 3

Central Core Disease; NADH-TR reaction staining; Malignant Hyperthermia

Question 4

A patient presents with kyphoscoliosis, congenital hypotonia and has delayed motor milestones. What is the disease? What are the inclusion bodies called? What are they derived from? What genes are responsible for this abnormality?

Answer 4

In Rod (Nemaline) Myopathy; Rods; Z band; Nebulin, Alpha-actin, Alpha and Beta tropomyosin

Question 5

A patient presents with bilateral ptosis and slow progressive limb girdle muscular dystrophy. What is the likely Dx? What gene is responsible?

Answer 5

Central nuclear myopathy; Dynamin 2

Question 6

What is the genetic inheritance of myotubular myopathy? What gene is responsible?

Answer 6

X-linked inheritance; Myotubularin gene