Unexplained fainting, near drowning and unusual seizures in childhood: screening for long QT syndrome in New Zealand families

Aims. To construct detailed pedigrees of five New Zealand families with aut osomal dominant long QT syndrome (LQTS) and screen selected individuals bas ed on initial symptomatic and ECG data. Methods. Clinical data were collected using a questionnaire and relevant me dical record review. Participants were then classified according to ECG dia gnostic criteria based on the presence or absence of symptoms and the rate- corrected QT interval (QTc) into three groups: affected, uncertain or unaff ected. Blood samples were also collected from each participant and DNA extr acted for genetic testing. Results. Seventy-eight family members were screened. The majority of the 35 symptomatic family members, who were affected on these criteria, had prese nted with symptoms in childhood. Of the remaining 43 asymptomatic family me mbers, the majority were in the uncertain diagnostic group based on these E CG criteria. Conclusions. Autosomal dominant long QT syndrome (Romano Ward syndrome) is being increasingly recognised and must be considered in the investigation o f children who present with unexplained fainting, near drowning, unusual se izures and sudden death. Screening long QT syndrome families based on ECG c riteria remains difficult, leaving a number of family members with an uncer tain diagnosis. It is hoped that genetic testing will become useful for dia gnosis of presymptomatic carriers of long QT syndrome in New Zealand in the future.