Channelopathy Reading

Question 1

Skeletal channelopathies are clinically divided into. . .

Answer 1

. . . periodic paralyses and non-dystrophic myotonias

Question 2

___ is a hallmark of skeletal channelopathy

Answer 2

Paroxysmal or episodic pattern is a hallmark of skeletal channelopathy

Question 3

Andersen-Tawill syndrome

Answer 3

The only known skeletal muscle channelopathy which also affects cardiac muscle.

The classical triad is that of hypokalemic periodic paralysis, cardiac conduction defects, and dysmorphic features (which may be subtle).

Question 4

While channelopathies may cause myotonia, by far the most common cause of myotonia is. . .

Answer 4

. . . myotonic dystrophy

Question 5

EMG-NCS in channelopathies

Answer 5

Often not helpful/normal

Question 6

Diagram of common skeletal muscle channelopathies

Answer 6

Question 7

SCNA1

Answer 7

Encodes sodium channel Nav1.1. Gene mutated in 80% of cases of severe myoclonic epilepsy of infancy, characterized by intractable seizures and developmental delay beginning in the first year of life. Mutations are typically de novo.

Nav1.1 channels have a regulatory role in inhibitory GABAergic neurons. Loss of their function in this inhibitory network leads to excitotoxicity of the rest of the CNS.

Question 8

Genes associated with severe myoclonic epilepsy of infancy

Answer 8

SCNA1, SCN1B, SCN2A, GABRG2 (the last being a GABA receptor subunit)

Question 9

Epilepsy syndromes associated with sodium channelopathies

Answer 9

Question 10

Epilepsy syndromes associated with potassium channelopathies

Answer 10

Question 11

Epilepsy syndromes associated with calcium channelopathies

Answer 11