Autosomal Dominant Long QT Syndrome

A cardiovascular disorder characterized by prolongation of the QT interval on ECG and presence of syncope, seizures, and sudden death.

 

Etiology:

 Five genes have been implicated in Romano-Ward syndrome, the autosomal dominant form of LQTS:

  1. KVLQT1
  2.  HERG
  3.  SCN5A
  4. KCNE1
  5. KCNE2

Manifestations:

clinical features of LQTS result from episodic ventricular tachyarrhythmias

  1. torsade de pointes  – refers to a specific variety of ventricular tachycardia that exhibits distinct characteristics on the electrocardiogram (ECG).
  2. ventricular fibrillation

Treatment and Management:

Presymptomatic diagnosis of LQTS is currently based on prolongation of the QT interval on ECG.

Genetic studies, have shown that diagnosis based solely on ECG is neither sensitive nor specific.

 Genetic screening using mutational analysis can improve presymptomatic diagnosis.

Patients with mutations in KVLQT1, HERG, KCNE1, and KCNE2,  may benefit from potassium therapy.

Conversely, sodium channel blockers might be helpful in patients with SCN5A mutations

Keating,  Mark T,  Lehmann, Michael H., Moss,  Arthur J. ,Priori, Silvia, Robinson, Jennifer L., Schwartz,  Peter J, Shen, Jiaxiang, Splawski, Igor, Timothy,  Katherine W.,  Towbin, Jeffrey A., and Vincent, G. Michael. 2000. Spectrum of Mutations in Long-QT Syndrome Genes. Circulation. 102:1178-1185.

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