DNA was extracted from venous blood samples from each heroin dependent subject, and from 10mm punches (PKU Guthrie cards) for controls, using chemagic Magnetic Separation Module I (chemagen AG) according to manufacturer’s protocol. A Biomek FXp robot was used for DNA aliquoting in 384 well plates and TaqMan assays for genotyping the 118A>G polymorphism on a 7900HT Fast Real-Time PCR System (both from Applied Biosystems). SDS v2.2.2 analysis software tool was used for base-calling and visualization of the genotype data. For quality control purposes, four samples from each plate were re-genotyped on another plates (no errors were detected). The call rate for the five case and the four control 384 plates was over 95 %. The data were analyzed using PLINK (Purcell et al., 2007) and SAS® software. Statistical power analyses were done using Quanto (Gauderman et al., 2006).
