Familial cramp due to potassium-aggravated myotonia.

Painful cramps and giant myotonic discharges in a family with the Nav1.4-G1306A mutation.

INTRODUCTION Two previously reported Norwegian patients with painful muscle cramps and giant myotonic discharges were genotyped and compared with those of members of 21 families harboring the same mutation. METHODS Using primers specific for SCN4A and CLCN1, the DNA of the Norwegian family members was amplified and bidirectionally sequenced. Clinical and neurophysiological features of other f...

A novel N440K sodium channel mutation causes myotonia with exercise-induced weakness - exclusion of CLCN1 exon deletion/duplication by MLPA

We report a 4-generation Turkish family with 10 affected members presenting with myotonia and potassium- and exercise-induced paralytic attacks. The clinical presentation was neither typical for the chloride channel myotonias Thomsen and Becker nor for the separate sodium channel myotonia entities potassium-aggravated myotonia, paramyotonia congenita, and hyperkalemic periodic paralysis. It is ...

Clinical Diversity of SCN4A-Mutation-Associated Skeletal Muscle Sodium Channelopathy

BACKGROUND AND PURPOSE Mutations of the skeletal muscle sodium channel gene SCN4A, which is located on chromosome 17q23-25, are associated with various neuromuscular disorders that are labeled collectively as skeletal muscle sodium channelopathy. These disorders include hyperkalemic periodic paralysis (HYPP), hypokalemic periodic paralysis, paramyotonia congenita (PMC), potassium-aggravated myo...

Sodium channelopathies in skeletal muscle and brain

Ion channel disorders are rare inherited diseases providing interesting models to study dysfunction of excitability in vivo and in vitro. The first socalled ‘channelopathies’ identified were skeletal muscle diseases, the myotonias and hyperkalemic periodic paralysis (HyperPP), which are sodium or chloride channel disorders. Within the last 5–10 years, complementary genetic and electrophysiologi...

Myotonia Acquisita