DNA was isolated from blood using a Gentra AutoPure Kit (Qiagen, Valencia, CA), buccal swabs with the BuccalAmp DNA Extraction Kit (Epicenter Technologies, Madison, WI), mouthwash samples with the Gentra Puregene Kit (Qiagen), and paraffin-embedded tissue with the QIAamp DNA Mini Kit (Qiagen) using standard protocols. TaqMan Genotyping Assays (Applied Biosystems, Foster City, CA) were used to detect polymorphisms in rs8034191, rs1051730, and rs931794. DNA isolated from buccal cells or from paraffin blocks was preamplified in an outer polymerase chain reaction for added sensitivity. Either 25 ng DNA or 1 µL of the outer nest was amplified, with primers designed using Primer Express software (Applied Biosystems), and detected using an AB 7900 Sequence Detection System (Applied Biosystems). For quality control, 5% of the products were sequenced and 10% were directly repeated.
