Purpose: To confirm the high frequency of interleukin (IL)-1beta-511T allele occurrence in patients with temporal lobe epilepsy (TLE) and hippocampal sclerosis (HS), with special attention given to the impact of prolonged febrile convulsions (PFCs) on IL-1beta genotype distribution.
Methods: Patients with evidence of unilateral HS on magnetic resonance (MR) images were chosen as study subjects (TLE+HS; n = 66). Other patients with essentially normal MRI findings or only foreign tissue (TLE without HS; TLE-HS; n = 64), and those with symptomatic localization-related epilepsy but without TLE (SLE; n = 89) were selected as disease controls. A single base pair polymorphism at position 2511 in the promoter region of the IL-1beta gene was analyzed.
Results: The distribution of IL-1beta-511 genotypes as well as allele frequency was significantly different between TLE+HS patients and controls. In contrast, no difference was found between TLE-HS patients and controls or between SLE patients and controls. Further, in the group of patients with TLE+HS, the frequency of the IL-1beta-511T allele tended to increase as a function of febrile convulsions [0.531 without either PFC or simple febrile convulsion (SFC); 0.633 with SFC; 0.686 with PFC]. Although no statistically significant difference was noted between patients without PFC and the controls, a chi2 analysis of allele distribution revealed a significant difference between those with PFC and the controls.
Conclusions: PFC proved to be a potent determinant of IL-1beta-511T allele frequency; thus a discrepancy of PFC incidence should be considered an explanation of recent conflicting results regarding the association between the gene polymorphisms of IL-1beta-511 and TLE+HS.