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Disease Profile

Andersen-Tawil syndrome

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset






Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Long QT syndrome 7; LQT7; Potassium-sensitive periodic paralysis, ventricular ectopy, and dysmorphic features;


Congenital and Genetic Diseases; Heart Diseases; Nervous System Diseases;


Andersen-Tawil syndrome is a type of long QT syndrome and is also considered a rare form of periodic paralysis. It causes episodes of muscle weakness, changes in heart rhythm (arrhythmia), and developmental abnormalities. Physical abnormalities associated with this condition typically affect the head, face, and limbs. About 60% of cases of Andersen-Tawil syndrome are caused by mutations in the KCNJ2 gene. The cause of the remaining cases remains unknown. This condition is inherited in an autosomal dominant pattern.[1][2]


Anderson-Tawil syndrome causes episodes of muscle weakness (periodic paralysis), changes in heart rhythm (arrhythmia), and developmental abnormalities. The most common changes affecting the heart are ventricular arrhythmia, which is a disruption in the rhythm of the heart's lower chambers, and long QT syndrome. Long QT syndrome is a heart condition that causes the heart muscle to take longer than usual to recharge between beats. If untreated, the irregular heartbeats can lead to discomfort, fainting, or cardiac arrest.[1]

Physical abnormalities associated with Andersen-Tawil syndrome typically affect the head, face, and limbs. These features often include a very small lower jaw (micrognathia), dental abnormalities, low-set ears, widely spaced eyes, and unusual curving of the fingers or toes (clinodactyly). Some affected people also have short stature and an abnormal curvature of the spine (scoliosis).[1]

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
5%-29% of people have these symptoms
Specific learning disability
Percent of people who have these symptoms is not available through HPO
Antegonial notching of mandible
Autosomal dominant inheritance
Bidirectional ventricular ectopy
Narrow opening between the eyelids
Short fingers or toes
Broad forehead
Increased width of the forehead
Wide forehead

[ more ]

Bulbous nose
Cleft palate
Cleft roof of mouth
Clinodactyly of the 5th finger
Permanent curving of the pinkie finger
Clinodactyly of the 5th toe
Delayed eruption of permanent teeth
Delayed eruption of adult teeth
Delayed skeletal maturation
Delayed bone maturation
Delayed skeletal development

[ more ]

Facial asymmetry
Asymmetry of face
Crooked face
Unsymmetrical face

[ more ]

Growth abnormality
Abnormal growth
Growth issue

[ more ]

High palate
Elevated palate
Increased palatal height

[ more ]

Wide-set eyes
Widely spaced eyes

[ more ]

Low blood potassium levels
Hypoplasia of dental enamel
Underdeveloped teeth enamel
Hypoplasia of the maxilla
Decreased size of maxilla
Decreased size of upper jaw
Maxillary deficiency
Maxillary retrusion
Small maxilla
Small upper jaw
Small upper jaw bones
Upper jaw deficiency
Upper jaw retrusion

[ more ]

Joint laxity
Joint instability
Lax joints

[ more ]

Low-set ears
Low set ears
Lowset ears

[ more ]

Malar flattening
Zygomatic flattening
Abnormally small skull
Decreased circumference of cranium
Decreased size of skull
Reduced head circumference
Small head circumference

[ more ]

Failure of development of more than six teeth
Missed heart beat
Skipped heart beat

[ more ]

Periodic hypokalemic paresis
Persistence of primary teeth
Delayed loss of baby teeth
Failure to lose baby teeth
Retained baby teeth

[ more ]

Preauricular pit
Pit in front of the ear
Prolonged QT interval
Prominent frontal sinuses
Prominent U wave
Scapular winging
Winged shoulder blade
Short foot
Short feet
Small feet

[ more ]

Short mandibular rami
Short metacarpal
Shortened long bone of hand
Short metatarsal
Short long bone of foot
Short palm
Short palpebral fissure
Short opening between the eyelids
Short phalanx of finger
Short finger bones
Slender long bone
Long bones slender
Thin long bones

[ more ]

Small hand
Disproportionately small hands
Fainting spell
Toe syndactyly
Fused toes
Webbed toes

[ more ]

Triangular face
Face with broad temples and narrow chin
Triangular facial shape

[ more ]



Yes, the Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

The diagnosis of Andersen-Tawil syndrome might be suspected in individuals with either:[2]

1. Two of the following three criteria:

  • Periodic paralysis
  • Symptomatic cardiac arrhythmias or evidence of enlarged U-waves, ventricular ectopy, or a prolonged QTc or QUc interval on electrocardiogram (ECG)
  • Characteristic facial features, dental abnormalities, small hands and feet, and at least two of the following:
    • Low-set ears
    • Widely spaced eyes
    • Small lower jaw (mandible)
    • Fifth-digit clinodactyly (curved pinky finger)
    • Syndactyly


2. One of the above three criteria in addition to at least one other family member who meets two of the three criteria.

The presence of a mutation in the KCNJ2 gene confirms the diagnosis of Andersen-Tawil syndrome.[2]

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.
  • Orphanet lists international laboratories offering diagnostic testing for this condition.


    Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

    Organizations Supporting this Disease

      Organizations Providing General Support

        Learn more

        These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

        Where to Start

        • Genetics Home Reference (GHR) contains information on Andersen-Tawil syndrome. This website is maintained by the National Library of Medicine.
        • The National Heart, Lung, and Blood Institute (NHLBI) has information on this topic. NHLBI is part of the National Institutes of Health and supports research, training, and education for the prevention and treatment of heart, lung, and blood diseases.

          In-Depth Information

          • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
          • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
          • MeSH® (Medical Subject Headings) is a terminology tool used by the National Library of Medicine. Click on the link to view information on this topic.
          • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
          • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
          • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
          • PubMed is a searchable database of medical literature and lists journal articles that discuss Andersen-Tawil syndrome. Click on the link to view a sample search on this topic.



              1. Andersen-Tawil syndrome. Genetics Home Reference. April 2006; https://ghr.nlm.nih.gov/condition/andersen-tawil-syndrome. Accessed 8/18/2015.
              2. Statland JM, Tawil R, Venance SL. Andersen-Tawil Syndrome. GeneReviews. August 6, 2015; https://www.ncbi.nlm.nih.gov/books/NBK1264/. Accessed 8/18/2015.

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