PCDH19 mutation in Japanese females with epilepsy

To determine the significance of PCDH19 mutations in Japanese females with epilepsy and to delineate their phenotypes.

PCDH19 sequencing analysis was performed in 116 females with various epilepsies, including 97 with Dravet syndrome (83.6%). They were referred for SCN1A analysis, and 52 carried SCN1A mutations.

Seven heterozygous mutations in exon 1 were identified in 7 patients (6.0%): 2 frameshift, 2 nonsense, and 3 missense mutations. One patient was a monozygotic twin, and her sister with mild phenotype carried the same mutation. The main clinical features among these 8 patients included early seizure onset (≤25 months of age), seizure clusters (7/8), fever-associated seizures (7/8), single seizure type (6/8), and late deterioration of intellect (5/8). Seizure durations were generally up to a few minutes, and only one patient developed status epilepticus once. The main seizure types were generalized tonic-clonic (4/8), tonic (3/8) and focal seizures, with (2/8) or without secondary generalization (3/8). Myoclonic, atonic and absence seizures were extremely rare. Two patients had Dravet syndrome (25%), and this proportion was significantly smaller than that in the total subjects (p<0.01).

PCDH19 mutation is a relatively frequent cause of epilepsy in Japanese females. Dravet syndrome was rare in our cohort.