Generalized epilepsy with febrile seizures plus: further heterogeneity in a large family.
BACKGROUND
Generalized epilepsy with febrile seizures plus (GEFS(+)) is a recently described benign childhood-onset epileptic syndrome with autosomal dominant inheritance. The most common phenotypes are febrile seizures (FS) often with accessory afebrile generalized tonic-clonic seizures (GTCS, FS(+)). In about one third, additional seizure types occur, such as absences, myoclonic, or atonic seizures. So far, three mutations within genes encoding subunits of neuronal voltage-gated Na(+) channels have been found in GEFS(+) families, one in SCN1B (beta(1)-subunit) and two in SCN1A (alpha-subunit).


METHODS
The authors examined the phenotypic variability of GEFS(+) in a five-generation German family with 18 affected individuals. Genetic linkage analysis was performed to exclude candidate loci.


RESULTS
Inheritance was autosomal dominant with a penetrance of about 80%. A variety of epilepsy phenotypes occurred predominantly during childhood. Only four individuals showed the FS or FS(+) phenotype. The others presented with different combinations of GTCS, tonic seizures, atonic seizures, and absences, only in part associated with fever. The age at onset was 2.8 +/- 1.3 years. Interictal EEG recordings showed rare, 1- to 2-second-long generalized, irregular spike-and-wave discharges of 2.5 to 5 Hz in eight cases and additional focal parietal discharges in one case. Linkage analysis excluded the previously described loci on chromosomes 2q21-33 and 19q13. All other chromosomal regions containing known genes encoding neuronal Na(+) channel subunits on chromosomes 3p21-24, 11q23, and 12q13 and described loci for febrile convulsions on chromosomes 5q14-15, 8q13-21, and 19p13.3 were also excluded.


CONCLUSIONS
These results indicate further clinical and genetic heterogeneity in GEFS(+).
Lerche
H
H
Department of Neurology, University of Ulm, Germany. holger.lerche@medizin.uni-ulm.de
Weber
Y G
YG
Baier
H
H
Jurkat-Rott
K
K
Kraus de Camargo
O
O
Ludolph
A C
AC
Bode
H
H
Lehmann-Horn
F
F
D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography; D004829:Epilepsy, Generalized / Q000175:diagnosis / Q000235:genetics*; D005192:Family Health; D005260:Female; D018740:Genetic Heterogeneity; D008040:Genetic Linkage; D005858:Germany; D006239:Haplotypes; D006801:Humans; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D019683:Penetrance; D003294:Seizures, Febrile / Q000175:diagnosis / Q000235:genetics*