| Phenotype details |
delayed development prior to seizure onset, smiling; seizure onset 17m, febrile seizure; after seizure onset severe intellectual disability, few single words, walks independently, regression with seizure onset loss of speech; atonic seizures (onset 24m), myoclonic (onset uncertain), non-convulsive status epilepticus (onset 2y10m), atypical absence seizures (onset 27m), seizure offset 5y, rare febrile tonic-clonic seizures from 4y2m; EEG generalized spike-wave, polyspike wave, biposterior quadrant epileptiform activity R>L, slow background, atypical absence seizure with 1.5–2.5 Hz generalized spike-wave; MRI brain 23m-normal, 5y-mild cerebellar atrophy, mild reduction in white matter volume; Genua valgum (knock knees), no dysmorphic or behavioral features |