A novel mutation in human ether-a-Go-Go-related gene, alanine to proline at position 490, found in a large family with autosomal dominant long QT syndrome

Long-QT syndrome is a rare disease characterized by prolonged ventricular repolarization. The clinical presentation of long-QT syndrome is the occurrence of syncope, seizures, or cardiac arrest in young patients. Previous studies have demonstrated locus heterogeneity, with causative mutations reported in >= 8 different genes, including the human ether-a-go-go-related gene. This study was conducted in 26 members of a 4-generation family with long-QT syndrome. The proband was a 14-year-old female patient referred to the emergency department for the evaluation of recurrent syncope associated with a prolonged QT interval on electrocardiography at rest. There was a family history of sudden death in a 27-year-old woman. Sequencing of the entire coding regions of the human ether-a-go-go-related gene and the intron and exon boundaries of the proband identified a single base-pair substitution (guanine to cytosine at nucleotide 1468). This mutation resulted in a novel missense mutation, alanine to proline at position 490 (Ala490Pro), in the inner loop of the S-2 and S-3 domains. The proband was heterozygous for the Ala490Pro mutation. To address whether the mutational change detected in the patient would be a polymorphism, 100 control subjects from the same ethnical background were investigated. None showed the Ala490Pro substitution. Of 26 family members, 9 were mutation carriers, and none had normal electrocardiographic results. The penetrance of this pedigree was assumed to be 100%. In conclusion, the Ala490Pro mutation of the human ether-a-go-go-related gene is a rare, novel mutation that was inherited in this family, leading to Romano-Ward syndrome with complete penetrance. (c) 2007 Elsevier Inc. All rights reserved.