Question: What is (are) Hypokalemic periodic paralysis ?
Answer: 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. The duration and frequency of the episodes may vary. Hypokalemic periodic paralysis is caused by mutations in the CACNA1S and SCN4A genes which are inherited in an autosomal dominant fashion. A small percentage of people with the characteristic features of hypokalemic periodic paralysis do not have identified mutations in these genes. In these cases, the cause of the condition is unknown. Paralytic crises can be treated with oral or IV potassium. Other management includes prevention of crises and support of specific symptoms.
Source: GARD

Question: What are the symptoms of Hypokalemic periodic paralysis ?
Answer: What are the signs and symptoms of Hypokalemic periodic paralysis? Hypokalemic periodic paralysis involves attacks of muscle weakness or loss of muscle movement (paralysis) that come and go. The weakness or paralysis is most commonly located in the shoulders and hips, affecting the muscles of the arms and legs. Muscles of the eyes and those that help you breathe and swallow may also be affected. There is normal muscle strength between attacks. Attacks usually begin in adolescence, but they can occur before age 10. How often the attacks occur varies. Some people have attacks every day, while others have them once a year. Episodes of muscle weakness usually last between a few hours and a day. 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, alcohol, 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, repeated episodes can lead to persistent muscle weakness later in life. People with hypokalemic periodic paralysis 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. The Human Phenotype Ontology provides the following list of signs and symptoms for Hypokalemic periodic paralysis. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms. Signs and Symptoms Approximate number of patients (when available) Myopathy 7.5% Autosomal dominant inheritance - Episodic flaccid weakness - Hypokalemia - Incomplete penetrance - Periodic hyperkalemic paralysis - The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature. The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined. Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.
Source: GARD

Question: What causes Hypokalemic periodic paralysis ?
Answer: What causes hypokalemic periodic paralysis? Hypokalemic periodic paralysis is caused by mutations in the CACNA1S and SCN4A genes. The CACNA1S and SCN4A genes provide instructions for making proteins that play an essential role in muscles used for movement (skeletal muscles). For the body to move normally, these muscles must tense (contract) and relax in a coordinated way. Muscle contractions are triggered by the flow of certain positively charged atoms (ions) into muscle cells. The CACNA1S and SCN4A proteins form channels that control the flow of these ions. The channel formed by the CACNA1S protein transports calcium ions into cells, while the channel formed by the SCN4A protein transports sodium ions. Mutations in the CACNA1S or SCN4A gene alter the usual structure and function of calcium or sodium channels. The altered channels cannot properly regulate the flow of ions into muscle cells, which reduces the ability of skeletal muscles to contract. Because muscle contraction is needed for movement, a disruption in normal ion transport leads to episodes of severe muscle weakness or paralysis. A small percentage of people with the characteristic features of hypokalemic periodic paralysis do not have identified mutations in the CACNA1S or SCN4A gene. In these cases, the cause of the condition is unknown.
Source: GARD

Question: Is Hypokalemic periodic paralysis inherited ?
Answer: How is hypokalemic periodic paralysis inherited? This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person has one parent with the condition.
Source: GARD

Question: How to diagnose Hypokalemic periodic paralysis ?
Answer: How is hypokalemic periodic paralysis diagnosed? The diagnosis of hypokalemic periodic paralysis is based on a history of episodes of paralysis and low levels of potassium in the blood during attacks (less than 0.9 to 3.0 mmol/L), but not between attacks. An important part of the diagnosis is to rule out other potential causes, including myotonia, hyperthyroidism, and arrhythmia. Affected individuals typically have a family history consistent with autosomal dominant inheritance. Genetic testing is available for hypokalemic periodic paralysis. Of all individuals meeting diagnostic criteria for this condition, approximately 55 to 70 percent have mutations in the CACNA1S gene, and approximately 8 to 10 percent have mutations in the SCN4A gene. GeneTests lists the names of laboratories that perform clinical genetic testing of the CACNA1S and SCN4A genes for hypokalemic periodic paralysis. When a disease-causing mutation is identified in an affected individual, genetic testing can be performed for at-risk, asymptomatic family members. Please note: Most of the laboratories listed through GeneTests do not accept direct contact from patients and their families; therefore, if you are interested in learning more, you will need to work with a health care provider or a genetics professional. See below for a list of online resources that can assist you in locating a genetics professional near you.
Source: GARD