PCDH19 and cholesteryl ester measurement: This unique pattern of inheritance and, consequently, the disease mechanism can be best explained by the ‘cellular interference’ model postulating that X-inactivation in CE females and mosaicism in CE males results in altered networks and communications between the PCDH19-Wildtype (WT) and Mutant (MT) expressing neurons, eventually leading to seizures and CE comorbidities [1].