Hypokalaemic periodic paralysis

Figure 4. Mutations in the human Cavl.l and Cay 1.2 (L-type) voltage-gated calcium channels associated with Hypokalaemic Periodic Paralysis (HypoPP) and Timothy Syndrome (TS), respectively. Also shown is the nucleotide deletion in the mouse Cay 1.1 homolog associated with Muscular Dysgenesis...

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Lerche H, Klugbauer N, Lehmann-Horn F, Hofmann F, Melzer W (1996) Expression and functional characterization of the cardiac L-type calcium channel carrying a skeletal muscle DHP-receptor mutation causing hypokalaemic periodic paralysis. Pflugers Arch 431 461-463. 

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Fontaine B, Vale-Santos J, Jurkat-Rott K et al 1994 Mapping of the hypokalaemic periodic paralysis (HypoPP) locus to chromosome lq31-32 in three European families. Nat Genet 6 267-272... 

Crill Has anyone looked at the acquired form of hypokalaemic periodic paralysis in orientals ... 

Ptacek Again, those are pretty rare. The patients are thyrotoxic and they have paralysis just like the hypokalaemics, except that when you ablate their thyroid, the thyrotoxic periodic paralysis resolves. There was one small family reported. I believe that this is a hereditary disorder, but we don t see it as a hereditary disorder much because it is a predisposing mutation and you also have to be thyrotoxic for the paralysis to manifest. We ve looked for Ca channel mutations in those patients but haven t found any. 

Ptacek The one thing that is different is that their K levels tend to be much lower. The familial hypokalaemic patients would typically have a K+level of2.1—3.2 during an attack. If I see a patient that has a l< level of 1.7—1.9 (which is alarmingly low), the first thing I think of is thyrotoxic periodic paralysis, because they tend to be really low. I don t know precisely why this is the case. 

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