DNA was extracted from previously prepared lymphoblastoid cell lines using standard methods (Qiagen, MD, USA). It has been established that conversion of cells into lymphoblastoid lines does not cause errors into SNP genotyping (Herbeck et al., 2009). Genotyping was performed by Prevention Genetics (Marshfield, WI, USA). Allele frequencies were: Val 0.53, Met 0.47. Genotype frequencies were: ValVal (VV) homozygotes 0.3, ValMet (VM) heterozygotes 0.46, and MetMet (MM) homozygotes 0.24, and did not deviate from Hardy-Weinberg equilibrium (p = 0.2) (i.e. genotype frequencies were as would be predicted from allele frequencies in the absence of factors such as non-random mating or selection).
