Key result
A homozygous 1893insC mutation in the KCNQ1 gene was identified in a 7-year-old boy with recessive Romano-Ward syndrome, severe QTc prolongation (up to 700 ms), and repeated syncope.
Case Report (n=3)
This case highlights that apparently normal individuals carrying heterozygous latent ion channel gene mutations may have a reduced repolarization reserve, while homozygous mutations can cause severe recessive Romano-Ward Syndrome.
Supports recessive KCNQ1-related Romano-Ward syndrome; leaves open validation of reduced repolarization reserve in heterozygotes.
In a 7-year-old boy with normal hearing suffering from repeated syncope an extremely prolonged QTc interval (up to 700 ms) was found. The mother was completely asymptomatic and the father had an intermittently borderline QTc interval (maximum 470 ms) but no symptoms. In the proband a mutation analysis of KCNQ1 gene revealed a homozygous 1893insC mutation. The parents were heterozygous for this mutation. There was no consanguineous marriage in the family. The clinical relevance of these findings is that apparently normal individuals may have a latent reduction of repolarizing currents, a "reduced repolarization reserve," because they are carriers of latent ion channel genes mutations.
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Novotný et al. (2006) conducted a case report in Recessive Romano-Ward Syndrome (n=3). Homozygous 1893insC mutation in KCNQ1 gene was evaluated on QTc interval prolongation and syncope. A homozygous 1893insC mutation in the KCNQ1 gene was identified in a 7-year-old boy with recessive Romano-Ward syndrome, severe QTc prolongation (up to 700 ms), and repeated syncope.
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