FHF1 (FGF12) epileptic encephalopathy

Voltage-gated sodium channels (Navs) are mainstays of neuronal function, and mutations in the genes encoding CNS Navs (Nav1.1 [ SCN1A ], Nav1.2 [ SCN2A ], Nav1.3 [ SCN3A ], and Nav1.6 [ SCN8A ]) are causes of some of the most common and severe genetic epilepsies and epileptic encephalopathies (EE).1 Fibroblast-growth-factor homologous factors (FHFs) compose a family of 4 proteins that interact with the C-terminal tails of Navs to modulate the channels' fast, and long-term, inactivations.2 FHF2 mutation is a rare cause of generalized epilepsy with febrile seizures plus (GEFS+).3 Recently, a de novo FHF1 mutation (p.R52H) was reported in early-onset EE in 2 siblings.4 We report 3 patients from unrelated families with the same FHF1 p.R52H mutation. The 5 cases together frame the FHF1 R52H EE from infancy to adulthood. As discussed below, this gain-of-function disease may be amenable to personalized therapy. Acknowledgment: The study has UK Research Ethics Committee's approval (10/H0305/83, granted by the Cambridge South REC, and GEN/284/12 granted by the Republic of Ireland REC). The research team acknowledges the support of the National Institute for Health Research through the Comprehensive Clinical Research Network, the Health Innovation Challenge Fund (grant HICF-1009-003), and the Wellcome Trust Sanger Institute (grant WT098051). BAM holds the University of Toronto Michael Bahen Chair in Epilepsy Research. The authors thank the Next Generation Sequencing/bioinformatics teams at McGill University, the Genome Quebec Innovation Center, the Reseau de Medecine Genetique Appliquee, and Drs. Ledia Brunga (DNA sample management); Dipayan Mitra (MRI); Ms. Gail Charlton (EEG); and Ms. Sylvia Dobrzeniecka (sequencing) for their efforts.