The many faces of neuromuscular disease

It has been said that "the face is the mirror of the mind." It also appears that the face may reflect a state of generalized disease. Familiarity with the common facial features of neuromuscular disease can assist in correct diagnosis and treatment of these conditions, which may present many faces. Four photographs exhibiting some of the neuromuscular diseases discussed in this article have been provided (see box) to test your skill in diagnosis. The correct answers are below the pictures.     

Voltage-gated sodium channels: action players with many faces

Voltage-gated sodium channels are responsible for the upstroke of the action potential and thereby play an important role in propagation of the electrical impulse in excitable tissues like muscle, nerve and the heart. Duplication of the sodium channels encoding genes during evolution generated the sodium channel gene family with the different isoforms differing in biophysical properties and tissue distribution. In this review article, mutations in these genes leading to various inherited disorders are discussed.