Table 1

Summary of clinical details of the 293 patients included in the multicentre systematic survey

Gender162 females, 131 males
Mean age at last follow-up22 years, SD 16, median 19, range 8 months to 69 years
Patients deceased17 (6%)
Family history of epilepsy or febrile seizures131 (45%)
Type of putative causal genetic abnormalitySNV248 (85%)
CNV17 (6%)
SNV+CNV2 (1%)
Chromosomal imbalance21 (7%)
Repeat expansion5 (2%)
Mean age at seizure onset4 years, SD 5, median 1, range 1 day to 30 years
Mean age at clinical diagnosis of the epilepsy syndrome11 years, SD 13, median 5, range antenatal to 58 years
Mean age at genetic diagnosis16 years, SD 15, median 13, range 1 day to 63 years
Mean interval from clinical to genetic diagnosis5 years, SD 10, median 0, range 4 years earlie to 52 years afterwards
Developmental delay or regression216 patients (75%)
Mean age at onset of developmental slowing16 months, SD 16, median 10, range from birth to 96 months
History of febrile seizures106 (36%)
Drug-resistant epilepsy240 (82%)
  • CI, chromosomal imbalance; CNV, copy number variant; SNV, single-nucleotide variant.