View source for Hyperkalaemic periodic paralysis

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==Overview==
'''Hyperkalaemic periodic paralysis''' is a [[genetic disorder]] which occurs in both humans and horses.  It is characterized by muscle hyperexcitability or weakness which, exacerbated by [[potassium]] or cold,  can lead to uncontrolled shaking followed by [[paralysis]].  Onset in humans usually occurs in the twenties.

The [[mutation]] which causes this disorder is [[dominant gene| dominant]] with linkage to the
[[sodium channel]] expressed in [[muscle]] (called SCN4A).  In the presence of high potassium levels, sodium channels fail to activate properly.  The mutation causes single [[amino acid]] changes in parts of the channel which important for inactivation.

Equine hyperkalaemic periodic paralysis occurs in 1 in 50 [[quarter horse]]s and can be traced to a
single ancestor (A stallion named Impressive).  Episodes in these horses are commonly brought on by [[alfalfa]], which contains high levels of potassium.

==See also==
*[[Ion channel]]s


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