PCDH19 and cholesteryl ester measurement: PCDH19 clustering epilepsy (CE, previously known as girls clustering epilepsy, GCE; female-limited epilepsy, FE; or epilepsy and mental retardation limited to females, EFMR: OMIM #300088) is an X-linked encephalopathy with an incidence rate of 1 per 20,600 live-born females and is characterized by seizures with an average onset of 11.9 months [1,2,3,4,5].