PURPOSE: Severe myoclonic epilepsy of infancy (SMEI) is an intractable epilepsy of early childhood of unknown etiology. It is often associated with a family history of seizure disorders, but epilepsy phenotypes have not been well described. We sought to characterize the seizure phenotypes of relatives to better understand to the genetic basis of SMEI. METHODS: Probands with SMEI were identified, and systematic family studies were performed. Epilepsy syndromes were characterized in affected family members. RESULTS: Twelve probands with SMEI were identified. Eleven of the 12 probands with SMEI had a family history of seizures, and the twelfth was the result of a consanguineous marriage. We found that 16.7% of full siblings and 8.3% of parents had definite seizures. A total of 39 affected family members was identified. The most common phenotype was febrile seizures in 14, febrile seizures plus in seven, partial epilepsy in two, and there were single individuals with SMEI, myoclonic-astatic epilepsy, Lennox-Gastaut syndrome, and 13 cases with unclassified or unconfirmed seizures. CONCLUSIONS: The family history of seizures in SMEI is in keeping with the spectrum of seizure phenotypes seen in generalized epilepsy with febrile seizures plus (GEFS+). Our findings suggest that SMEI is the most severe phenotype in the GEFS+ spectrum.
PURPOSE: Severe myoclonic epilepsy of infancy (SMEI) is an intractable epilepsy of early childhood of unknown etiology. It is often associated with a family history of seizure disorders, but epilepsy phenotypes have not been well described. We sought to characterize the seizure phenotypes of relatives to better understand to the genetic basis of SMEI. METHODS: Probands with SMEI were identified, and systematic family studies were performed. Epilepsy syndromes were characterized in affected family members. RESULTS: Twelve probands with SMEI were identified. Eleven of the 12 probands with SMEI had a family history of seizures, and the twelfth was the result of a consanguineous marriage. We found that 16.7% of full siblings and 8.3% of parents had definite seizures. A total of 39 affected family members was identified. The most common phenotype was febrile seizures in 14, febrile seizures plus in seven, partial epilepsy in two, and there were single individuals with SMEI, myoclonic-astatic epilepsy, Lennox-Gastaut syndrome, and 13 cases with unclassified or unconfirmed seizures. CONCLUSIONS: The family history of seizures in SMEI is in keeping with the spectrum of seizure phenotypes seen in generalized epilepsy with febrile seizures plus (GEFS+). Our findings suggest that SMEI is the most severe phenotype in the GEFS+ spectrum.
Authors: Gemma L Carvill; Sarah Weckhuysen; Jacinta M McMahon; Corinna Hartmann; Rikke S Møller; Helle Hjalgrim; Joseph Cook; Eileen Geraghty; Brian J O'Roak; Steve Petrou; Alison Clarke; Deepak Gill; Lynette G Sadleir; Hiltrud Muhle; Sarah von Spiczak; Marina Nikanorova; Bree L Hodgson; Elena V Gazina; Arvid Suls; Jay Shendure; Leanne M Dibbens; Peter De Jonghe; Ingo Helbig; Samuel F Berkovic; Ingrid E Scheffer; Heather C Mefford Journal: Neurology Date: 2014-03-12 Impact factor: 9.910
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Authors: Thomas H Rhodes; Christoph Lossin; Carlos G Vanoye; Dao W Wang; Alfred L George Journal: Proc Natl Acad Sci U S A Date: 2004-07-19 Impact factor: 11.205