The combined novel KCNQ1 frameshift I145Sfs*92 and nonsense W392X variants caused Jervell and Lange-Nielsen syndrome in a Chinese infant presenting with sustained foetal bradycardia.

We report clinical and molecular analysis of an infant presenting with foetal bradycardia and clinical outcome of Jervell and Lange-Nielsen syndrome (JLNS). Clinical, electrocardiogram (ECG), and echocardiographic data were collected from members in a three-generation family. Whole exomes were amplified and sequenced for proband. The identified variants were verified in the remaining members. The pathogenicity of candidate variants was predicted using multiple software programmes. A 28-year-old non-consanguineous Chinese woman at 23 weeks' gestation presenting with sustained foetal bradycardia of 100 b.p.m. Immunological disorders and infection were excluded. The infant was delivered at 37 weeks' gestation with 2700-g birthweight. QTc was prolonged in both ECG and Holter recording. Hearing tests confirmed bilateral sensorineural hearing loss. Genetic testing demonstrated that the infant carried a novel frameshift c.431delC (p.I145Sfs*92) and a novel nonsense c.1175G>A (p.W392X) compound variants of KCNQ1 inherited from mother and father, respectively, in autosomal recessive inheritance. Only relative II-5 carrying heterozygous KCNQ1-I145Sfs*92 variant had prolonged QTc, while the other carriers did not have prolonged QT, suggesting an autosomal dominant inheritance of LQT1 phenotype with incomplete penetrance in the family. We report the novel frameshift KCNQ1-I145Sfs*92 and nonsense KCNQ1-W392X compound variants in autosomal recessive inheritance that caused JLNS presenting as sustained foetal bradycardia for the first time. Meanwhile, KCNQ1-I145Sfs*92 heterozygous variant demonstrated LQT1 phenotype in autosomal dominant inheritance with incomplete penetrance. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: journals.permissions@oup.com.

Citation

Yanmin Zhang, Xiaomin Li, Ying Yang, Jie Wang, Xinru Gao, Mengyun Fan. The combined novel KCNQ1 frameshift I145Sfs*92 and nonsense W392X variants caused Jervell and Lange-Nielsen syndrome in a Chinese infant presenting with sustained foetal bradycardia. Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology. 2020 Dec 23;22(12):1880-1884

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PMID: 32830254

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