Neurology: Case of the Month

Select the correct statement regarding recessive myotonia congenita:

[ A ] The clinical syndrome typically includes cataracts, testicular atrophy, and frontal baldness.
[ B ] Patients may complain of apparent weakness.
[ C ] Muscle hypertrophy and myotonic symptoms are not as severe as in dominant myotonia.
[ D ] Recessive myotonia congenita is thought to be caused by a genetic defect in the sodium channel.

All of the following statements are TRUE, EXCEPT:

[ A ] The genetic defect in paramyotonia congenita maps to mutations in the chloride channel.
[ B ] DNA analysis for myotonic dystrophy demonstrates an expanded trinucleotide repeat sequence on chromosome 19.
[ C ] Sodium channelopathies include hyperkalemic periodic paralysis and potassium aggravated myotonia.
[ D ] Myotonia fluctuans and myotonia permanens were previously known as sodium channel myotonia.

Symptoms of myotonia congenita typically includes:

Treatment of myotonia congenita includes all of the following, EXCEPT:

All of the following are correct, EXCEPT:

[ A ] Thomsen's and Becker's disease have been linked to chromosome 7q35 in the region of the human skeletal muscle chloride channel gene.
[ B ] Chloride channels account for 70-80% of skeletal muscle resting membrane conductance.
[ C ] The defect in the chloride channel is thought to reduce the rate of action potential repolarization.
[ D ] With loss of function of chloride channels, potassium decreases in the transverse tubule during repolarization.

Test Yourself — Patient 20