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| __NOTOC__ | | __NOTOC__ |
| {{Andersen-Tawil syndrome}} | | {{Andersen-Tawil syndrome}} |
| {{CMG}}; {{AE}} {{CP}}; {{RT}} | | {{CMG}} |
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| {{SK}} ATS; Andersen syndrome; Andersen cardiodysrhytmic periodic paralysis; long QT syndrome 7; LQT7; periodic paralysis, potassium sensitive cardiodysrhytmic type; hypokalemic periodic paralysis with cardiac arrhythmia | | {{SK}} Andersen syndrome; Andersen cardiodysrhytmic periodic paralysis; long QT syndrome 7; LQT7; periodic paralysis, potassium sensitive cardiodysrhytmic type; hypokalemic periodic paralysis with cardiac arrhythmia |
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| ==Overview== | | ==[[Andersen-Tawil syndrome overview|Overview]]== |
| Andersen-Tawil syndrome is a form of [[long QT syndrome]]. It is a rare genetic disorder, and is inherited in an [[autosomal dominant]] pattern and has characteristic features of episodes of [[paralysis]], [[ventricular arrhythmia]], and [[dysmorphic]] features such as [[hypertelorism]], [[micrognathia]], and low set ears. Patients with Andersen-Tawil syndrome usually present in childhood with spontaneous attacks of [[paralysis]] which may be associated with normal, high, or low potassium levels.
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| ==Historical Perspective== | | ==[[Andersen-Tawil syndrome historical perspective|Historical Perspective]]== |
| It is named for Ellen Andersen<ref>{{cite journal |author=Andersen ED, Krasilnikoff PA, Overvad H |title=Intermittent muscular weakness, extrasystoles, and multiple developmental anomalies. A new syndrome? |journal=Acta paediatrica Scandinavica |volume=60 |issue=5 |pages=559-64 |year=1971 |pmid=4106724 |doi=}}</ref>and R. Tawil.<ref name="pmid8080508">{{cite journal |author=Tawil R, Ptacek LJ, Pavlakis SG, ''et al'' |title=Andersen's syndrome: potassium-sensitive periodic paralysis, ventricular ectopy, and dysmorphic features |journal=Ann. Neurol. |volume=35 |issue=3 |pages=326-30 |year=1994 |pmid=8080508|doi=10.1002/ana.410350313}}</ref><ref>{{WhoNamedIt|synd|3410}}</ref>
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| ==Classification== | | ==[[Andersen-Tawil syndrome pathophysiology|Pathophysiology]]== |
| Two types of Andersen-Tawil syndrome are distinguished by their genetic causes.
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| * Type 1, which accounts for about 60 percent of all cases of the disorder, is caused by mutations in the ''[[KCNJ2]]'' [[gene]]. <ref>{{cite journal|author=Tristani-Firouzi M, Jensen JL, Donaldson MR, ''et al'' |title=Functional and clinical characterization of KCNJ2 mutations associated with LQT7 (Andersen syndrome) |journal=J. Clin. Invest. |volume=110 |issue=3 |pages=381-8 |year=2002 |pmid=12163457 |doi=}}</ref><ref>{{cite journal |author=Pegan S, Arrabit C, Slesinger PA, Choe S |title=Andersen's syndrome mutation effects on the structure and assembly of the cytoplasmic domains of Kir2.1 |journal=Biochemistry|volume=45 |issue=28 |pages=8599-606 |year=2006 |pmid=16834334 |doi=10.1021/bi060653d}}</ref>
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| * The remaining 40 percent of cases are designated as type 2; the cause of the condition in these cases is unknown.
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| ==Pathophysiology== | | ==[[Andersen-Tawil syndrome differential diagnosis|Differentiating Andersen-Tawil syndrome from other Diseases]]== |
| Andersen-Tawil syndrome affects the [[heart]], symptoms are a disruption in the rhythm of the heart's lower chambers (ventricular arrhythmia) in addition to the symptoms of long QT syndrome. There are also physical abnormalities associated with Andersen-Tawil syndrome, these typically affect the head, face, and limbs. These features often include an unusually small lower jaw ([[micrognathia]]), low-set ears, and an abnormal curvature of the fingers called [[clinodactyly]]. | |
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| ===Genetics=== | | ==[[Andersen-Tawil syndrome epidemiology and demographics|Epidemiology and Demographics]]== |
| The protein made by the ''KCNJ2'' gene forms a [[potassium channel|channel]] that transports potassium ions into [[muscle]] [[cell (biology)|cell]]s. The movement of potassium ions through these channels is critical for maintaining the normal functions of skeletal muscles which are used for movement and cardiac muscle. [[Mutation]]s in the ''KCNJ2'' gene alter the usual structure and function of potassium channels or prevent the channels from being inserted correctly into the cell membrane. Many mutations prevent a molecule called PIP2 from binding to the channels and effectively regulating their activity. These changes disrupt the flow of potassium ions in skeletal and cardiac muscle, leading to the periodic paralysis and irregular heart rhythm characteristic of Andersen-Tawil syndrome.
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| Researchers have not yet determined the role of the KCNJ2 gene in bone development, and it is not known how mutations in the gene lead to the developmental abnormalities often found in Andersen-Tawil syndrome.
| | ==[[Andersen-Tawil syndrome screening|Screening]]== |
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| | ==[[Andersen-Tawil syndrome natural history, complications and prognosis|Natural History, Complications and Prognosis]]== |
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| ==Diagnosis== | | ==Diagnosis== |
| ===Symptoms===
| | [[Andersen-Tawil syndrome diagnostic criteria|Diagnostic Criteria]] | [[Andersen-Tawil syndrome history and symptoms|History and Symptoms ]] | [[ Andersen-Tawil syndrome physical examination|Physical Examination]] | [[Andersen-Tawil syndrome laboratory findings|Laboratory Findings]] | [[Andersen-Tawil syndrome electrocardiogram|Electrocardiogram]] |[[Andersen-Tawil syndrome chest x ray|Chest X Ray]] | [[Andersen-Tawil syndrome CT|CT]] | [[Andersen-Tawil syndrome MRI|MRI]] | [[Andersen-Tawil syndrome echocardiography or ultrasound|Echocardiography or Ultrasound]] | [[Andersen-Tawil syndrome other imaging findings|Other Imaging Findings]] | [[Andersen-Tawil syndrome other diagnostic studies|Other Diagnostic Studies]] |
| *[[Seizures]] - due to [[oxygen]] deprivation that occurs during [[arrhythmia]].
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| *[[Fainting]] - fainting or [[syncope]] is the most common symptom LQTS.
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| * A prodrome may occur before losing consciousness, which may consist of [[lightheadedness]], heart [[palpitations]], [[blurred vision]] or [[weakness]].
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| *[[Sudden death]] - a fatal [[arrhythmia]] that is not quickly intervened on, may cause sudden death.
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| ===Physical Examination===
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| ====Head====
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| Findings may include: | |
| * Hypoplastic mandible
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| * [[Micrognathia]]
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| ====Eyes====
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| * [[Hypertelorism]] may be noted on physical examination.
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| ====Nose====
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| * Broad nose may be seen.
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| ====Ears====
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| * Low set ears may be present.
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| ====Extremities==== | | ==Treatment== |
| * [[Clinodactyly]] may be present.
| | [[Andersen-Tawil syndrome medical therapy|Medical Therapy]] | [[Andersen-Tawil syndrome surgery |Surgery]] | [[Andersen-Tawil syndrome primary prevention|Primary Prevention]] | [[Andersen-Tawil syndrome secondary prevention|Secondary Prevention]] | [[Andersen-Tawil syndrome tertiary prevention|Tertiary Prevention]] | [[Andersen-Tawil syndrome cost-effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Andersen-Tawil syndrome future or investigational therapies|Future or Investigational Therapies]] |
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| ===Electrocardiogram=== | | ==Case Studies== |
| Although [[polymorphic ventricular tachycardia]] is a common [[arrhythmia]] in patients with Anderson syndrome, decompensation into a hemodynamically compromising rhythm, or ventricular fibrillation, is rare. The following [[EKG]] findings are seen in patients with Andersen-Tawil syndrome:
| | [[Andersen-Tawil syndrome case study one|Case #1]] |
| *Biphasic U waves in limb leads
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| *Widened T-U junction
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| *Large U waves
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| *Prolonged terminal T wave downslope
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| ==References== | | ==References== |