Analyses from a subsample (N = 1,091) of the present study have previously been reported [Gillespie et al., 2005]. Differences between the studies are detailed in the supplementary information but briefly, we have, (a) invested substantial effort to improve the genotyping (discussed in Materials and Methods Section), (b) have subtyped the L allele by rs25531, (c) increased the sample size threefold, and (d) improved the models and methods of analysis.
