High frequency of mosaic pathogenic variants in genes causing epilepsy-related neurodevelopmental disorders.

PurposeMosaicism probably represents an underreported cause of genetic disorders due to detection challenges during routine molecular diagnostics. The purpose of this study was to evaluate the frequency of mosaicism detected by next-generation sequencing in genes associated with epilepsy-related neurodevelopmental disorders.MethodsWe conducted a retrospective analysis of 893 probands with epilepsy who had a multigene epilepsy panel or whole-exome sequencing performed in a clinical diagnostic laboratory and were positive for a pathogenic or likely pathogenic variant in one of nine genes (CDKL5, GABRA1, GABRG2, GRIN2B, KCNQ2, MECP2, PCDH19, SCN1A, or SCN2A).