BabyScreen+ newborn screening

Gene: KCNH2

Green List (high evidence)

Rated as 'strong actionability' in paediatric patients by ClinGen.

The mean age at presentation of LQTS is 14 years. Cardiac events may occur at any age, but are most common from the pre-teen years through the 20s. Cardiac events are often triggered by administration of a QT-prolonging drug or hypokalemia. It has been estimated that 50% or fewer of untreated individuals with a pathogenic variant in one of the genes associated with LQTS have symptoms, usually one to a few syncopal events. Of individuals who die of complications of LQTS, death is the first sign of the disorder in an estimated 10-15%.

In patients with LQTS with a resting QTc greater than 470ms, a beta blocker is recommended.

Implantation with an implantable cardioverter defibrillator (ICD) can be effective in reducing SCD in LQTS patients.

With all forms of LQTS, a degree of caution with sporting activity is recommended.

Because the risk of adverse events increases in patients with LQTS with prolongation of the QTc >500 ms, QT-prolonging medications and electrolyte depleting medications (e.g. diuretics) should not be used in patients with LQTS unless there is no suitable alternative. Episodes of torsades de pointes can be precipitated by exposure to a QT prolonging medication, or hypokalemia induced by diuretics or gastrointestinal illness.

Created: 29 Dec 2022, 10:49 p.m. | Last Modified: 29 Dec 2022, 10:49 p.m.

Panel Version: 0.1761

Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted

Phenotypes
Long QT syndrome 2, MIM# 613688