Clinical and genetic correlations in transient prolongation of the QT interval: from diagnostic difficulties to an algorithm for personalized monitoring
ORIGINAL PAPERS
Abstract
LongQ–Tsyndrome (LQTS) is a genetically determined disorder characterized by prolongation of theQTinterval (assessed by electrocardiography) and is associated with an increased risk of sudden cardiac death. According to epidemiological studies,LQTSis responsible for 3000–4000 sudden deaths annually in the United States, predominantly among physically active young individuals. There are several molecular genetic subtypes ofLQTS, each demonstrating variable clinical expressivity and incomplete penetrance. In some patients with genetically confirmedLQTS, theQ–Tinterval remains within normal limits throughout life, and no clinical symptoms are observed (phenotype-negative carriers). Conversely, in some patients with confirmedQ–TSinterval prolongation, no disease-associated mutations can be identified in known genes (genotype-negativeLQTS). This study presents clinical cases illustrating both types of phenotype-genotype correlations inLQTS: the presence ofQTSprolongation in the absence of identified pathogenic variants (genotype-negative), as well as confirmed carriage of a pathogenic variant in the absence of electrocardiographic manifestations (phenotype-negative).
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