Andersen-Tawil syndrome. Hyperkalemic periodic paralysis. Hypokalemic periodic paralysis explained

 Let's break these down:

  1. Andersen-Tawil Syndrome (ATS)

    • Definition: Andersen-Tawil Syndrome is a rare genetic disorder that affects the heart, muscles, and other parts of the body.
    • Features: ATS is characterized by a triad of symptoms, although not everyone will have all three:
      • Periodic paralysis: Episodes of muscle weakness or paralysis.
      • Cardiac arrhythmias: Abnormal heart rhythms, particularly long QT syndrome which can lead to ventricular arrhythmias.
      • Dysmorphic features: Physical abnormalities like a small jaw, wide-set eyes, low-set ears, syndactyly (webbed or fused fingers or toes), and others.
    • Genetics: It's usually caused by mutations in the KCNJ2 gene, though not all cases have an identifiable mutation. The condition is inherited in an autosomal dominant pattern, meaning only one copy of the mutated gene is required to express the condition.
  2. Hyperkalemic Periodic Paralysis (HyperPP)

    • Definition: HyperPP is an inherited condition in which individuals have episodes of muscle weakness or paralysis that are associated with high levels of potassium in the blood (hyperkalemia).
    • Features: Symptoms usually start in infancy or early childhood and include:
      • Episodes of muscle weakness or paralysis which can last for minutes to hours.
      • Triggering factors can include rest after exercise, ingestion of potassium-rich foods, and stress.
      • Myotonia (muscle stiffness) can sometimes be seen.
    • Genetics: It's caused by mutations in the SCN4A gene, which codes for a sodium channel in muscle cells. It is inherited in an autosomal dominant manner.
  3. Hypokalemic Periodic Paralysis (HypoPP)

    • Definition: HypoPP is another inherited condition where individuals experience episodes of muscle weakness or paralysis associated with low levels of potassium in the blood (hypokalemia).
    • Features:
      • Muscle weakness or paralysis episodes which can last from hours to days.
      • These episodes often occur with triggers like carbohydrate-rich meals, stress, cold temperatures, or certain medications.
      • Over time, some people with HypoPP can develop permanent muscle weakness.
    • Genetics: Mutations in two primary genes, CACNA1S and SCN4A, have been linked to HypoPP. It's also inherited in an autosomal dominant pattern.

In all these conditions, early diagnosis and management are crucial, as some of them, especially ATS, can have life-threatening cardiac complications. Treatments may involve lifestyle modifications, medications to stabilize potassium levels or treat arrhythmias, and other supportive measures.

Related publication:

Paralogous annotation of disease-causing variants in long QT syndrome genes.
https://pubmed.ncbi.nlm.nih.gov/22581653/

KCNJ2 mutations in arrhythmia patients referred for LQT testing: a mutation T305A with novel effect on rectification properties.
https://pubmed.ncbi.nlm.nih.gov/17341397/

Genotypic heterogeneity and phenotypic mimicry among unrelated patients referred for catecholaminergic polymorphic ventricular tachycardia genetic testing.
https://pubmed.ncbi.nlm.nih.gov/16818210/

More publication at:
https://www.ncbi.nlm.nih.gov/snp/rs147750704#publications

and: https://www.ncbi.nlm.nih.gov/snp/rs199473381#publications
and:
https://www.ncbi.nlm.nih.gov/snp/rs202067116#publications

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