Genomic DNA was purified from human cerebellar tissue using DNeasy columns (Qiagen, Valencia, CA). Genotyping for the OPRM1 rs1799971 (Taqman Assay ID: C_8950074_1_) and rs2075572 (Taqman Assay ID: C_1691815_1_, Applied Biosystems, Foster City, CA) SNPs was performed as previously described.(18, 30) The PLINK 1.07 genetic association analysis program(31) was used to verify SNP data quality, test for departure from Hardy-Weinberg equilibrium, and test individual SNPs for statistical association with significance set at p<0.05.
