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Introduction
The first case of long QT syndrome was probably reported by Friedrich Ludwig Meissner in 1856 in Germany. He described the case of a deaf girl who collapsed and died while being publicly admonished at school. When the parents were informed, they revealed that two brothers of the girl had also died suddenly after a violent fright or rage.
In 1957, Anton Jervell and Fred Lange-Nielsen published the first complete description of long QT syndrome. The disease became known as Jervell, Lange-Nielsen syndrome, a condition causing profound hearing loss and disruption of the normal cardiac rhythm. This disorder is a form of long QT syndrome, in which cardiac muscle takes longer than usual to recharge between beats.1-5 If untreated, the arrhythmia can lead to recurrent syncope and sudden death.
Jervell, Lange-Nielsen syndrome is caused by mutations in the KCNE1 (potassium voltage-gated channel, Isk-related family, member 1) is a gene associated with Long QT syndrome and KCNQ1 (potassium voltage-gated channel, KQT-like subfamily, member 1) is the gene's official symbol genes (responsible for 10 and 90 per cent of cases, respectively). The proteins produced by these two genes work together to form a channel that transports positively charged potassium ions out of cells. The movement of potassium ions through these channels is critical in maintaining the normal functions of the inner ear and cardiac muscle. Mutations in the KCNE1 and KCNQ1 genes alter the usual structure and function of potassium channels or prevent the assembly of normal channels. These changes disrupt the flow of potassium ions in the inner ear and in cardiac muscle, leading to hearing loss and irregular cardiac rhythm.6-9
Despite these advances in the molecular genetic understanding of the condition, a diagnosis of congenital long QT syndrome is still based on electrocardiography (ECG) and clinical characteristics. Beta-blockers remain the mainstay of treatment. For high risk patients, an implantable cardioverter-defibrillator offers an effective therapeutic option to reduce mortality. Gene-based specific therapy is still preliminary. Further studies are required to investigate new strategies for targetting the defective genes or mutant channels.10 The prevalence of this syndrome in deaf children was found to average 0.21 per cent, with a range of 0-0.43 per cent.11 All children with...