Congenital long QT syndrome is electrocardiographically characterized by a prolonged QT interval and polymorphic ventricular arrhythmias (torsade de pointes). These cardiac arrhythmias may result in recurrent syncopes, seizure, or sudden death (Jongbloed et al., 1999).
Yang et al. (2010) studied a large, 4-generation Chinese family segregating autosomal dominant long QT syndrome (LQTS). The proband was a 62-year-old woman who had a 40-year history of syncopal episodes. Comprehensive clinical evaluation included an echocardiogram that ... Yang et al. (2010) studied a large, 4-generation Chinese family segregating autosomal dominant long QT syndrome (LQTS). The proband was a 62-year-old woman who had a 40-year history of syncopal episodes. Comprehensive clinical evaluation included an echocardiogram that showed no structural or functional cardiac abnormalities, but an electrocardiogram (ECG) that revealed a markedly prolonged QT interval (corrected QT = 520 ms). Subsequent evaluation of 49 family members identified 9 patients with LQTS characterized by similar clinical features. The proband developed persistent atrial fibrillation, which was also observed in 3 affected relatives. The proband had a younger brother who had a series of seizures and syncopal episodes after birth and died suddenly at 7 days of life.
In a large, 4-generation Chinese family with autosomal dominant long QT syndrome mapping to chromosome 11q23.3-q23.4, Yang et al. (2010) sequenced the candidate gene KCNJ5 and identified heterozygosity for a missense mutation (G387R; 600734.0001) in affected individuals. The ... In a large, 4-generation Chinese family with autosomal dominant long QT syndrome mapping to chromosome 11q23.3-q23.4, Yang et al. (2010) sequenced the candidate gene KCNJ5 and identified heterozygosity for a missense mutation (G387R; 600734.0001) in affected individuals. The mutation, which was not found in 528 ethnically matched controls, was also detected in 2 asymptomatic family members, indicating incomplete penetrance and a need for long-term monitoring of carriers.