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Epileptic encephalopathy (EE)refers tosevere often intractable seizure disorderswhere seizure-onset contributes to aprogressive disturbance in brain function. Itwas comprised by heterogeneous conditionsin which cognitive, sensory and/or motorfunctions deteriorate as a consequence ofepileptic activity, which consists of frequentseizures and/or major interictal paroxysmalactivity, and may occur at any age in earlychildhood. There are various causes of EEand genetic factors play a major role in theetiology. With the molecular revolution, thenumber of known monogenic determinantsunderlying the EE has grown rapidly. Thisstudy was designed to investigate a cohortof Chinese patients with unexplained earlyinfantile Epileptic Encephalopathy (EIEE).Whole exome sequencing (WES) wasperformed on 56 Chinese patients withunexplained EE to screen gene mutations.We identified 11 de novo pathogenicvariants in 20% patients (11/56) withseveral EE related genes: PCDH19 (n=2);CDKL5 (n=2); KCNQ2 (n=2); SCN2A(n=2); GRIN2A (n=1); CACNB4 (n=1);DEPDC5 (n=1). Nine of variants are novelvariants, and one of variants in KCNQ2 andCDKL5, respectively, was reported before.Furthermore, we found five inheritancemutations in PCDH19 (n=2), KCTD7 (n=1)and PRRT2 (n=2) may contribute to thepatients clinical traits. In this study, WESshowed a high diagnostic yield (28%) in Chinese patients with unexplained EIEE, aswell as enriching the EIEE mutationspectrum bank. These finding provide usefulinsights of early genetic testing to guide thetreatment strategy for non-Syndromicepileptic encephalopathy.

genetic testing;epileptic encephalopathy