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Hypokalemic periodic paralysis, type 1(HOKPP; HOKPP1)

MedGen UID:
Concept ID:
Disease or Syndrome
Synonym: HypoPP
Genes (locations): CACNA1S (1q32.1); SCN4A (17q23.3)
Monarch Initiative: MONDO:0042979
OMIM®: 170400

Disease characteristics

Excerpted from the GeneReview: Hypokalemic Periodic Paralysis
Hypokalemic periodic paralysis (hypoPP) is a condition in which affected individuals may experience paralytic episodes with concomitant hypokalemia (serum potassium <3.5 mmol/L). The paralytic attacks are characterized by decreased muscle tone (flaccidity) more marked proximally than distally with normal to decreased deep tendon reflexes. The episodes develop over minutes to hours and last several minutes to several days with spontaneous recovery. Some individuals have only one episode in a lifetime; more commonly, crises occur repeatedly: daily, weekly, monthly, or less often. The major triggering factors are cessation of effort following strenuous exercise and carbohydrate-rich evening meals. Additional triggers can include cold, stress/excitement/fear, salt intake, prolonged immobility, use of glucosteroids or alcohol, and anesthetic procedures. The age of onset of the first attack ranges from two to 30 years; the duration of paralytic episodes ranges from one to 72 hours with an average of nearly 24 hours. Long-lasting interictal muscle weakness may occur in some affected individuals and in some stages of the disease and in myopathic muscle changes. A myopathy may occur independent of paralytic symptoms and may be the sole manifestation of hypoPP. [from GeneReviews]
Frank Weber  |  Frank Lehmann-Horn   view full author information

Additional description

From MedlinePlus Genetics
Hypokalemic periodic paralysis is a condition that causes episodes of extreme muscle weakness typically beginning in childhood or adolescence. Most often, these episodes involve a temporary inability to move muscles in the arms and legs. Attacks cause severe weakness or paralysis that usually lasts from hours to days. Some people may have episodes almost every day, while others experience them weekly, monthly, or only rarely. Attacks can occur without warning or can be triggered by factors such as rest after exercise, a viral illness, or certain medications. Often, a large, carbohydrate-rich meal or vigorous exercise in the evening can trigger an attack upon waking the following morning. Although affected individuals usually regain their muscle strength between attacks, some develop persistent muscle weakness later in life.

People with hypokalemic periodic paralysis typically have reduced levels of potassium in their blood (hypokalemia) during episodes of muscle weakness. Researchers are investigating how low potassium levels may be related to the muscle abnormalities in this condition.  https://medlineplus.gov/genetics/condition/hypokalemic-periodic-paralysis

Clinical features

From HPO
Periodic paralysis
MedGen UID:
Concept ID:
Disease or Syndrome
Episodes of muscle weakness.
MedGen UID:
Concept ID:
Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.
MedGen UID:
Concept ID:
Disease or Syndrome
A disorder of muscle unrelated to impairment of innervation or neuromuscular junction.
Muscle weakness
MedGen UID:
Concept ID:
Reduced strength of muscles.
MedGen UID:
Concept ID:
An involuntary and painless delay in the relaxation of skeletal muscle following contraction or electrical stimulation.
Episodic flaccid weakness
MedGen UID:
Concept ID:
Recurrent episodes of muscle flaccidity, a type of paralysis in which a muscle becomes soft and yields to passive stretching.
MedGen UID:
Concept ID:
An abnormally decreased potassium concentration in the blood.

Professional guidelines


Fouad G, Dalakas M, Servidei S, Mendell JR, Van den Bergh P, Angelini C, Alderson K, Griggs RC, Tawil R, Gregg R, Hogan K, Powers PA, Weinberg N, Malonee W, Ptácek LJ
Neuromuscul Disord 1997 Jan;7(1):33-8. doi: 10.1016/s0960-8966(96)00401-4. PMID: 9132138
Elbaz A, Vale-Santos J, Jurkat-Rott K, Lapie P, Ophoff RA, Bady B, Links TP, Piussan C, Vila A, Monnier N
Am J Hum Genet 1995 Feb;56(2):374-80. PMID: 7847370Free PMC Article

Recent clinical studies


Wang Q, Zhao Z, Shen H, Bing Q, Li N, Hu J
Channels (Austin) 2021 Dec;15(1):20-30. doi: 10.1080/19336950.2020.1857980. PMID: 33345742Free PMC Article


Monteleone S, Lieb A, Pinggera A, Negro G, Fuchs JE, Hofer F, Striessnig J, Tuluc P, Liedl KR
Biophys J 2017 Oct 3;113(7):1485-1495. doi: 10.1016/j.bpj.2017.08.010. PMID: 28978442Free PMC Article

Clinical prediction guides

Monteleone S, Lieb A, Pinggera A, Negro G, Fuchs JE, Hofer F, Striessnig J, Tuluc P, Liedl KR
Biophys J 2017 Oct 3;113(7):1485-1495. doi: 10.1016/j.bpj.2017.08.010. PMID: 28978442Free PMC Article

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