PCDH19-related epilepsy and Dravet Syndrome: Face-off between two early-onset epilepsies with fever sensitivity

• Epilepsy onset is earlier in DS than in PCDH19-realted epilepsy.
• Myoclonic and clonic seizures occur only in DS.
• Seizures with affective symptoms mostly occur in PCDH19-related epilepsy.
• In PCDH19-related epilepsy seizures are mainly brief and clustered.
• PCDH19 gene should definitively considered as causes of a proper epileptic phenotype.

Aim of this study is to compare PCDH19-related epilepsy and Dravet Syndrome (DS) in order to find out differences between these two infantile epilepsies with fever sensitivity.We retrospectively reviewed the medical records of 15 patients with PCDH19-related epilepsy and 19 with DS. Comparisons were performed with Fisher’s exact test or Student's t-test.Females prevailed in PCDH19-related epilepsy. Epilepsy onset was earlier in DS (5.0 + 2.1 vs 11.2 + 7.0 months; p < 0.05). The second seizure/cluster occurred after a longer latency in PCDH19-related epilepsy rather than in DS (10.1 ± 13.6 vs 2.2 ± 2.1 months; p < 0.05). Seizures were mainly single and prolonged seizures in DS, and brief and clustered in PCDH19-related epilepsy. Myoclonic and clonic seizures have been found only in DS. Other types of seizures were found in both epilepsies with a prevalence of GTCS and atypical absences in DS, and focal motor and hypomotor seizures in PCDH19-related epilepsy. Seizures with affective symptoms have been confirmed to be typical of PCDH19-related epilepsy. Status Epilepticus equally occurred in both groups. Photosensitivity was detected only in DS. No differences were found about the presence of intellectual disabilities and behavioral disturbances.We were able to find out some distinctive features, which could address the diagnosis towards DS or PCDH19-related epilepsy, since first manifestation. These considerations suggest to definitively considering PCDH19 gene as cause of a proper epileptic phenotype.