PCDH19 and epilepsy: According to the previous literature review, epilepsy caused by PCDH19 variants occurs predominantly in heterozygous females and occasionally in mosaic males, whereas hemizygous males are unaffected.[6] The widely recognized pathogenic phenomenon was that the coexistence of mutant and wild-type PCDH19 cells in heterozygous females and mosaic males could interrupt cell–cell communication, and results in cell interference.[6–8] However, hemizygous males have only homologous PCDH19 mutant cells, and could not experience the cell interference.