Andersen-Tawil syndrome: Clinical presentation and predictors of symptomatic arrhythmias - Possible role of polymorphisms K897T in KCNH2 and H558R in SCN5A gene

J Cardiol. 2017 Nov;70(5):504-510. doi: 10.1016/j.jjcc.2017.01.009. Epub 2017 Mar 21.

Abstract

Background: Andersen-Tawil syndrome (ATS) is rare channelopathy caused by KCNJ2 mutation and probably KCNJ5. It is characterized by arrhythmias, neurological symptoms, and dysmorphic features. The present study retrospectively examined the characteristics of 11 unrelated families with ATS.

Methods: This study consisted of 11 probands positive for KCNJ2 variants and 33 family members (mean age 30.0±17.3 years, female n=31). Additional genetic screening of 3 LQTS genes (KCNQ1, KCNH2, SCN5A) was performed in 9 families. Predictors of arrhythmias [premature ventricular beats>2000/24h, biventricular and polymorphic ventricular tachycardia (VT)], syncope, and/or cardiac arrest (CA) were evaluated.

Results: In KCNJ2 mutation carriers vs non-carriers (n=25 vs n=19) significant differences were observed in U-wave manifestations in V2-V4, Tpeak-Tend duration, QTUc duration (p<0.0001), dysmorphic features, and neurological symptoms. Compared to asymptomatic carriers (n=9), in those with arrhythmias and/or syncope and/or CA (n=16) micrognathia (p=0.004), periodic paralysis (p=0.019), palpitation (p=0.005), U-wave n V2-V4 (p=0.049) were more frequent; QTU (p=0.045) and Tpeak-Tend (p=0.014) were also longer (n=9). In the subgroup of carriers with syncope and/or cardiac arrest (n=10, 90% women), K897T-KCNH2 polymorphism (p=0.02), periodic paralysis (p=0.004), muscle weakness (p=0.04), palpitations (p=0.04), arrhythmias (biventricular VT, p=0.003; polymorphic VT, p=0.009) were observed more frequently. Tpeak-Tend duration was longer (p=0.007) and the percentage of patients with premature ventricular contraction >2000/24h was higher (p=0.005).

Conclusion: A higher risk of arrhythmia, syncope, and/or CA is associated with the presence of micrognathia, periodic paralysis, and prolonged Tpeak-Tend time. Our findings suggest that K897T may contribute to the occurrence of syncope.

Keywords: Andersen-Tawil syndrome; Arrhythmia; K897T polymorphism; Long QT syndrome.

MeSH terms

  • Adolescent
  • Adult
  • Andersen Syndrome / genetics*
  • Child
  • Child, Preschool
  • ERG1 Potassium Channel / genetics*
  • Female
  • Genetic Testing
  • Heart Arrest / complications
  • Heart Arrest / genetics
  • Humans
  • Male
  • Micrognathism / complications
  • Micrognathism / genetics
  • Middle Aged
  • NAV1.5 Voltage-Gated Sodium Channel / genetics
  • Polymorphism, Genetic
  • Syncope / complications
  • Syncope / genetics*
  • Tachycardia, Ventricular / complications
  • Tachycardia, Ventricular / genetics
  • Ventricular Premature Complexes / complications
  • Ventricular Premature Complexes / genetics
  • Young Adult

Substances

  • ERG1 Potassium Channel
  • KCNH2 protein, human
  • NAV1.5 Voltage-Gated Sodium Channel
  • SCN5A protein, human