Arrhythmias and conduction disturbanceMutation-Specific Risk in Two Genetic Forms of Type 3 Long QT Syndrome
Section snippets
Methods
The study population of 85 patients was drawn from the International LQTS Registry. The 85 patients included 50 affected subjects from 3 unrelated families carrying the ΔKPQ mutation and 35 from 2 unrelated families from Israel carrying the D1790G mutation. The patients carrying the D1790G mutation were either from a large multigenerational kindred originating from Tunisia or a family from Israel. The SCN5A mutations were identified using standard genetic tests performed in academic
Results
The clinical characteristics of the patients with ΔKPQ and D1790G mutations are listed in Table 1. Patients with ΔKPQ mutations were more likely to be treated with β blockers, implanted defibrillators, left cervicothoracic sympathetic ganglionectomy, and pacemakers than were patients with D1790G mutations. Patients with D1790G mutations were primarily treated with flecainide. This medication was discontinued in 3 patients after new onset of a Brugada-type pattern on the electrocardiogram. Only
Discussion
This is the first study to investigate the clinical course of patients with the LQTS with 2 different LQT3 mutations. The findings demonstrated meaningful differences in the clinical severity between patients affected with the ΔKPQ and D1790G mutations, with ΔKPQ patients at a considerably greater risk of first cardiac events and recurrent syncope than those with the D1790 mutation.
LQT3 results from mutations of the SCN5A gene on chromosome 3p21 that affect the structure of the cardiac α
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This study was supported in part by research grants HL-33843 and HL-51618 (to Dr. Moss) from the National Institutes of Health, Bethesda, Maryland.