Abstracts

Rationale: Patients with mesial temporal lobe epilepsy (MTLE) and hippocampal sclerosis (HS) who are pharmacoresistant may undergo unilateral surgical excision of hippocampal formation as an alternative for seizure control. Surgical specimens of these patients offer a unique opportunity to address questions related to the mechanisms underlying hippocampal sclerosis (HS). We undertake the present study in order to determine gene expression profile of hippocampal tissue from patients with pharmacoresistant MTLE and to compare expression patterns in familial and sporadic forms of MTLE. Methods: Eight surgical specimens were obtained from patients with MTLE (n=4 from familial MTLE and n=4 from sporadic MTLE), as well as control tissues (n=3) from autopsy. This study was performed using the Human Genome U133 Plus 2.0 gene expression array (Affymetrix™). We used 5 µg of total RNA in the One-Cycle Target Labeling protocol (Affymetrix™). Data was acquired by GeneChip Scanner 3000 (Affymetrix™) and analyzed using DNA-Chip Analyzer (dChip). Statistical analysis was performed by t-test with p≤0.01 for a significant difference between groups. Results: We found that 101 genes were differentially expressed (up and down regulated) in samples from patients with MTLE (familial+sporadic) when compared to controls. There were 35 genes differentially expressed when we compared only patients with familial MTLE and controls; however, 64 genes were differentially expressed when comparing patients with sporadic MTLE and controls. In addition, there 191 genes up and down regulated when comparing samples from patients with familial and sporadic MTLE. Conclusions: Our results clearly show that, although similar in clinical, imaging and neuropathologic features, familial and sporadic forms of MTLE have distinct molecular signatures indicating a possible distinct biological mechanism.