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Overlap of Congenital Deafness and Long QT Syndrome With Distinct Genetic Basis: A Diagnostic Challenge
Romana Pirah1, Arshad Ali1, Faisal Qadir1
1Department of Cardiac Electrophysiology, National Institute of Cardiovascular Diseases, Karachi, Pakistan.
Background:
Prolonged QT interval on electrocardiogram along with sensorineural deafness is consistent with Jervell and Lange-Nielsen syndrome (JLNS). We report a case where genetic testing revealed different mutations for each manifestation.
Case Summary:
A 5-year-old girl with congenital deafness presented with a history of palpitations. Baseline corrected QT (QTc) interval was 481 ms, and exercise stress test revealed QTc of 491 ms at 4 minutes of recovery. Family screening revealed another sibling to be deaf; screening electrocardiogram and exercise stress test also disclosed prolonged QTc interval. Genetic testing showed heterozygous pathogenic mutation in the KCNQ1 gene and a likely pathogenic homozygous mutation in the PCDH15 gene.
Discussion:
JLNS is the combination of prolonged QT interval with sensorineural deafness. Our patient was clinically suspected of having JLNS, however, genetic testing revealed the presence of 2 different mutations responsible for QT prolongation and deafness, representing the coincidence of 2 independent genetic disorders rather than JLNS only.
Take-Home Message:
Long QT syndrome in combination with deafness should be confirmed with genetic testing, as their combined presence can be a coincidental finding.
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