Hyperkalemic periodic paralysis

Hyperkalemic periodic paralysis, abbreviated HYPP or HyperKPP, is an inherited autosomal dominant disorder that affects sodium channels in muscle cells and the ability to regulate potassium levels in the blood. It is characterized by muscle hyperexcitability or weakness which, made worse by potassium, heat or cold, can lead to uncontrolled shaking followed by paralysis. Onset usually occurs in early childhood, although it also occurs in adults. The causal mutation lies in the SCN4A gene, which is linked to the sodium channel expressed in muscle, and it changes single amino acids in parts of the channel that are important for inactivation, impairing the fast inactivation of the channel after an action potential. This record describes the condition and is not medical advice.