Cor Vasa 2002, 43(5):250-252

New mutation in the KCNQ1 gene identified in a Czech patient with the LQT phenotype

Tomáš Novotný^1,*, Jitka Kadlecová², Renata Gaillyová², Bořivoj Semrád¹

¹ Interní kardiologická klinika, Fakultní nemocnice Brno - pracoviště Bohunice

² Oddělení lékařské genetiky, Fakultní nemocnice Brno, Brno, Česká republika

Background:
The long QT syndrome (LQTS) is a monogenic disorder characterized by prolongation of the QT interval on ECG and syncope or sudden death caused by polymorphic ventricular tachycardia (torsade de pointes). To date, six loci and five genes have been related to this syndrome. The most commonly affected are the KCNQ1 (11p15.5) and HERG (7q35-36) genes.

Methods and results:
KCNQ1 gene analysis (multiplex single strand conformational polymorphism and DNA sequence analysis - ABI Prism 310 sequencer) was performed in 12 families with the clinical diagnosis of LQTS. In two of them, mutations in the KCNQ1 gene were found. In 10 members of one large family, a mutation G973A (G325R) was identified. This mutation was described by other authors previously. In another family, a KCNQ1 mutation C926T was found in exon 7. It results in the substitution of isoleucine for tyrosine at position 309 (T309I) within the pore region. This yet undescribed mutation was identified in one affected individual, the other relatives are either healthy or have died.

Conclusion:
Identification of a novel mutation confirms the heterogeneous nature of LQTS.

Keywords: Long QT syndrome; KCNQ1; Gene; Mutation

Published: May 1, 2002  Show citation