Which of the following channelopathies is associated with calcium channel disorder of muscles?
Ans. a (Hypokalemic periodic paralysis). (Ref. Harrison medicine 15th ed., -2295, 16th ed., 2339, 2363, 2536)1.Spinocerebellar ataxia 1Trinucleotide repeat (CAC) expansion in gene.2.Episodic ataxia type 1K channel gene mutations.3.Hypokalemic periodic paralysisL- type Ca++ channelopathy.4.Hyperkalemic periodic paralysisPoint mutation sodium channel.5.Malignant hyperthermiaMutation in Ryanodine receptor gene.6.MyotoniaMutation in Cl channel gene.Educational points:Clinical Features of Periodic Paralysis and Nondystrophic Myotonias Calcium ChannelSodium Channel Potassium ChannelFeatureHypokalemic PPHyperkalemic PPParamyotoniaCongenitaAnderson's SyndromeMode of InheritanceADADADADAge of onsetAdolescenceEarly childhoodEarly childhoodEarly childhoodMyotoniaNoYesYesNoEpisodic weaknessYesYesYesYesFrequency of attacks of weaknessDaily to yearlyMay be 2-3/dWith cold, usually rareDaily to yearlyDuration of attacks of weakness2-12 hFrom 1-2 h to >1 day2-24 h2-24 hSerum K+ level during attacks of weaknessDecreasedIncreased or normalUsually normalVariableEffect of K+ loadingNo changeIncreased myotonia, then weaknessIncreased myotoniaNo changeEffect of muscle coolingNo changeIncreased myotoniaIncreased myotonia, then weaknessNo changeFixed weaknessYesYesYesYes
Hypokalemic periodic paralysis
Episodic ataxia type 1
Hyperkalemic periodic paralysis
Paralysis Spinocerebellar ataxia 1.
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