Familial temporal lobe epilepsy (FTLE, ETL) is a genetically heterogeneous syndrome characterized by relatively benign simple or complex partial seizures with intense psychic or autonomic auras (Berkovic et al., 1996).
For a discussion of genetic heterogeneity ... Familial temporal lobe epilepsy (FTLE, ETL) is a genetically heterogeneous syndrome characterized by relatively benign simple or complex partial seizures with intense psychic or autonomic auras (Berkovic et al., 1996). For a discussion of genetic heterogeneity of temporal lobe epilepsy, see ETL1 (600512).
Berkovic et al. (1996) reported 38 individuals from 13 unrelated families with familial temporal lobe epilepsy. Of 22 monozygotic twin pairs in which 1 or both twins had partial epilepsy, 5 pairs were concordant and all had cryptogenic ... Berkovic et al. (1996) reported 38 individuals from 13 unrelated families with familial temporal lobe epilepsy. Of 22 monozygotic twin pairs in which 1 or both twins had partial epilepsy, 5 pairs were concordant and all had cryptogenic TLE. Mean age of onset in all patients was 24 years, and none had a history of prenatal or perinatal insult or illness. Thirty-four individuals had simple partial seizures, with psychic or autonomic components suggestive of a limbic or mesial temporal origin. Twenty-five individuals had complex partial seizures, and 25 had rare generalized tonic-clonic seizures. Brain MRI of 17 patients showed no abnormalities. In most subjects, seizures were mild, infrequent, and responsive to treatment. Berkovic et al. (1996) noted that the mild and sometimes subtle nature of the symptoms were often not reported. Analysis of the families involved suggested autosomal dominant inheritance with incomplete penetrance. The authors noted that the disorder showed similarities to the 'El' mouse, a genetic model of TLE involving a major gene on mouse chromosome 9 (see ANIMAL MODEL). Cendes et al. (1998) described the clinical characteristics of 30 patients with TLE from 11 kindreds. Mean age of onset was 12 years. Seizure types included simple partial (55%), complex partial (81%), and rare secondarily generalized tonic-clonic (75%). Those with simple partial seizures had psychic, autonomic, and sensory manifestations. Seizures were well-controlled only in some patients, and 11 of 18 patients with available MRI had findings compatible with mesial temporal sclerosis. Cendes et al. (1998) noted that some of their patients resembled those reported by Berkovic et al. (1996), but that many had a more severe course, indicating clinical heterogeneity, and possibly genetic heterogeneity. Gambardella et al. (2000) reported a large kindred from southern Italy with benign familial temporal lobe epilepsy with age of onset ranging from 17 to 52 years (mean, 27 years). The disorder was characterized by partial seizures with vegetative or experiential phenomena, suggestive of a temporal origin. Rare complex partial seizures and generalized seizures also occurred. Neurologic examination and brain imaging were normal. Genealogic study strongly supported autosomal dominant inheritance with incomplete penetrance. Santos et al. (2002) reported 14 unrelated families in which 72 members were affected with temporal lobe epilepsy with ictal semiology of a mesial temporal onset and MRI abnormalities in the mesial structures. In 1 large family, the authors excluded linkage to the locus on chromosome 10q for lateral temporal lobe epilepsy (ETL1; 600512). Santos et al. (2002) emphasized the clinical and genetic heterogeneity among familial forms of TLE. Depondt et al. (2002) reported a 5-generation family affected by familial temporal lobe epilepsy and febrile seizures but without hippocampal sclerosis. The disease phenotype was characterized by temporal lobe epilepsy, no deja vu or auditory or visual hallucinations, a high incidence of febrile seizures, mean age at onset of afebrile seizures of 8 years, low incidence of epileptic features on electroencephalography, no hippocampal sclerosis, and a usually good prognosis. Of 22 patients in the family, 10 had febrile seizures and epilepsy, 11 had epilepsy only, and 1 had febrile seizures only. All febrile seizures ceased by the age of 6 years. Spontaneous remission occurred in 11 patients; 3 patients had refractory seizures. An autosomal dominant pattern of inheritance with reduced disease penetrance of 80% was seen. Gurnett et al. (2007) reported a North American Caucasian family in which 7 members had febrile seizures, 3 of whom developed childhood afebrile seizures. Four individuals had febrile status epilepticus, 3 required intensive care unit hospitalization, and 1 had significant global developmental delay as a consequence. Seizures were generalized tonic-clonic, although 2 patients had febrile seizures with focal features. Gurnett et al. (2007) emphasized that none of the individuals manifested clear evidence of temporal lobe epilepsy.