During the last wave of the current study, subjects were also phlebotomized to provide biomaterial for future studies. DNA from 516 subjects was prepared from these specimens using cold protein precipitation [17]. The resulting DNA was spectrophotometrically analyzed then diluted to 50 ng/μl. The DNA samples were then re-coded to insure anonymity, and shipped to Sequenom Inc (San Diego, USA), who performed the genotyping analyses of the single nucleotide polymorphisms (SNP) listed in Table 1 using their proprietary matrix-assisted laser desorption-ionization mass spectroscopy (MassARRAY®).
