A 7-year-old boy with bilateral sensorineural deafness presents with a syncopal seizure. ECG shows a corrected QT of 560 ms. Family history reveals a similarly affected cousin whose parents are unaffected. What is the inheritance pattern and associated genetic defect?

• A Autosomal dominant KCNH2 mutation
• B X-linked recessive SCN5A mutation
• C Autosomal recessive KCNQ1 mutation ✓
• D Autosomal recessive RYR2 mutation

Explanation

Jervell and Lange-Nielsen syndrome combines congenital long QT with sensorineural deafness and is inherited autosomal recessively, usually from homozygous KCNQ1 mutations abolishing the IKs potassium current; heterozygous parents typically show mild QT prolongation or nothing. Autosomal dominant long QT without deafness is Romano-Ward syndrome, commonly KCNH2 or KCNQ1 related. RYR2 mutations cause catecholaminergic polymorphic VT, which structurally mimics LQT1 exercise-triggered events but has a normal resting QT interval.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.