RETRACTED: Association of μ-opioid receptor subunit gene and idiopathic generalized epilepsy (Retracted Article. See vol. 64, pg 579, 2005)

Objective: To replicate and extend the previously reported association between the opioid receptor mu subunit gene (OPRM1) and idiopathic absence epilepsy (IAE), using a sample of 230 probands with idiopathic generalized epilepsy (IGE). Background: In humans and in animal models, several lines of evidence implicate opioid receptors with seizures. The G118 allele of OPRM1 was associated with IAE (p = 0.019). Methods: Three single nucleotide, polymorphisms (SNP) of OPRM1 were investigated by association studies with IGE using a case/control design. one of which also used a within-family design. Results: Association was found for G118 with IGE (p = 0.00027, odds ratio [OR] - 1.86), replicating the previous association. Within-family tests of linkage and association (haplotype-based haplotype relative risk and transmission disequilibrium test) confirmed this result. Further evidence for involvement of OPRM1 in IGE was provided by an association with G-172T, located in the 5' untranslated region (p = 0.0015, OR = 2.36). Haplotypes of the two SNPs were associated with IGE with a greater level of significance (p = 0.000087) suggesting that both SNPs might be in linkage disequilibrium with a single functional variant. Analysis of the results by subgroups of IGE showed association with all subgroups tested. Conclusions: These results confirm the previous association and support the hypothesis of a role for OPRM1 in IGE, including absence syndromes. However, the authors found no evidence for a specific association between OPRM1 and idiopathic absence epilepsy. The data suggest that the functional variant predisposing to IGE is located within 60kb of exon 1.