Prevalence of Jervell-Lange Nielsen syndrome in children with congenital bilateral sensorineural hearing loss

OBJECTIVE
Long QT syndrome (LQTS) is an inherited cardiac ion channel disorder (channelopathy) that is characterized by prolonged QT intervals on the electrocardiography (ECG) and possess the risk of sudden cardiac death (SCD). Jervell-Lange Nielsen syndrome (JLNS) is a specific subtype of LQTS that is accompanied by congenital sensorineural hearing loss, inherited autosomal recessively, and higher risk of SCD. In this study, we aimed to investigate JLNS prevalence in deaf children attending special schools for hearing loss, located in our province.

METHODS
An ECG screening program was conducted in 6 special schools for children with hearing loss in İstanbul and a total of 440 students between 6 and 18 years old were included. Corrected QT interval (QTc) was calculated using the Bazett formula. Notably, 51 students, detected with any abnormal finding on ECG, were invited to our center for a comprehensive examination.

RESULTS
A total of 8 patients were found with a prolonged QT interval. JLNS was diagnosed in 4 (0.9%) patients. In addition, 2 students had already been diagnosed with JLNS at another center earlier. The other 2 students, being siblings, were newly diagnosed with JLNS; and appropriate treatment was initiated. Genetic testing revealed a pathological homozygous mutation in KCNQ1 gene. The younger sibling (Case 1), who possessed a QTc of greater than 500 ms and a history of syncope, which was very suspicious for SCD, was implanted an implantable cardioverter-defibrillator. Propranolol treatment was initiated for both siblings.

CONCLUSION
JLNS should be carefully considered and screened, especially in patients with a history of congenital deafness.