Neurology: Case of the Month

With what part of the muscle fiber are the nemaline bodies most closely associated?

Which of the following statements is TRUE?

[ A ] Nemaline rods are seen only in nemaline myopathy.
[ B ] The weakness in nemaline myopathy is responsive to steroid therapy.
[ C ] In the case of nemaline myopathy, respiratory weakness may occur at a time when limb muscle weakness is mild.
[ D ] CPK is always elevated in nemaline myopathy.
[ E ] The number of nemaline rods seen on biopsy correlates directly with the degree of weakness in that muscle.

Immunocytochemistry reveals the components of the nemaline rods to include ALL, EXCEPT:

Changes that may be noted on microscopy in nemaline myopathy include ALL, EXCEPT:

[ A ] Type 1 fiber predominance.
[ B ] Ragged red fibers.
[ C ] Fiber size disproportion with type 2 fibers being larger than type 1 fibers.
[ D ] Red or purple "rods" seen on modified Gomori trichrome staining.
[ E ] Rods clustered under the sarcolemma and around the nuclei.

True statements regarding the genetics of nemaline myopathy include ALL, EXCEPT:

[ A ] The NEM1 locus on chromosome 1 has been linked to a childhood onset autosomal dominant form of nemaline myopathy.
[ B ] Alpha-tropomyosin has been identified as the disease gene on chromosome 1 causing autosomal dominant nemaline myopathy.
[ C ] The degree of penetrance in autosomal dominant nemaline myopathy is low.
[ D ] An autosomal recessive form of nemaline myopathy has been linked to chromosome 2. Mutations in the merosin gene have been found responsible.

Test Yourself — Patient 34