PCDH19 and epilepsy: Other studies have found that the level of allopregnanolone (AP) in PCDH19 female epilepsy patients was decreased (Tan et al., 2015), and AP is the most effective positive regulator of GABAAR which mediates fast inhibitory neurotransmission in the brain, so PCDH19 as a key modulator of GABAergic transmission and may suggest new pathogenic mechanisms.