Childhood absence epilepsy (CAE, ECA), a subtype of idiopathic generalized epilepsy (EIG; 600669), is characterized by a sudden and brief impairment of consciousness that is accompanied by a generalized, synchronous, bilateral, 2.5- to 4-Hz spike and slow-wave discharge ... Childhood absence epilepsy (CAE, ECA), a subtype of idiopathic generalized epilepsy (EIG; 600669), is characterized by a sudden and brief impairment of consciousness that is accompanied by a generalized, synchronous, bilateral, 2.5- to 4-Hz spike and slow-wave discharge (SWD) on EEG. Seizure onset occurs between 3 and 8 years of age and seizures generally occur multiple times per day. About 70% of patients experience spontaneous remission of seizures, often around adolescence. There are no structural neuropathologic findings in patients with ECA (Crunelli and Leresche, 2002). The ECA1 locus has been mapped to chromosome 8q24; see also EIG1 (see 600669), which also maps to 8q24. Susceptibility to the development of childhood absence epilepsy may be conferred by variation in several genes: ECA2 (607681), conferred by variation in the GABRG2 gene (137164) on chromosome 5q31.1; ECA4 (611136), conferred by variation in the GABRA1 gene (137160) on chromosome 5q34; ECA5 (612269), conferred by variation in the GABRB3 gene (137192) on chromosome 15q11-q12, and ECA6 (see 611942), conferred by variation in the CACNA1H gene (607904) on chromosome 16p13. See EIG11 (607628) for discussion of a locus previously designated ECA3 on chromosome 3q26.
Childhood absence epilepsy accounts for 5 to 15% of childhood epilepsies (Fong et al., 1998).
Manifestations begin at age 6-7 years, in contrast to juvenile absence epilepsy (JAE; 607631), which begins around puberty. The main features ... Childhood absence epilepsy accounts for 5 to 15% of childhood epilepsies (Fong et al., 1998). Manifestations begin at age 6-7 years, in contrast to juvenile absence epilepsy (JAE; 607631), which begins around puberty. The main features are frequent absence seizures (several per day) and bilateral, synchronous, symmetric 3-Hz spike waves on EEG. Generalized tonic-clonic seizures (GTCS) often develop during adolescence. Otherwise, absence seizures may either remit or persist into adulthood (Commission on Classification and Terminology of the International League Against Epilepsy, 1989). Fong et al. (1998) defined 3 subsyndromes of ECA. The first subsyndrome, which accounts for approximately 40 to 60% of ECA patients, is characterized by absence seizures as the sole phenotype and remits spontaneously during adolescence. The second subsyndrome, which accounts for another 40% of ECA patients, persists into adolescence and adulthood, during which patients develop tonic-clonic seizures. The third subsyndrome accounts for a smaller percentage (possibly 10 to 12%) of ECA patients and is characterized by the development of tonic-clonic and myoclonic seizures during adolescence, after the onset of absences in childhood. Wallace et al. (2001) stated that febrile seizures (121210) occur in about 3% of children and that 10 to 15% of persons with childhood absence epilepsy have febrile seizures before the onset of epilepsy. Febrile convulsions are a common seizure type in relatives of childhood absence epilepsy probands (Italian League Against Epilepsy Genetic Collaborative Group, 1993).
Overall, the annual incidence of childhood absence epilepsy is 2 to 8 per 100,000 children under the age of 15 to 16 years, with a prevalence of 2 to 10% among children with any type of epilepsy (Crunelli ... Overall, the annual incidence of childhood absence epilepsy is 2 to 8 per 100,000 children under the age of 15 to 16 years, with a prevalence of 2 to 10% among children with any type of epilepsy (Crunelli and Leresche, 2002).