substantial correlation with a positive response to 20 mg (Figure 2B). Rs3784943 falls within the 8th intron of the gene cadherin 13 (CDH13) which codes for a cell adhesion molecule that is highly expressed in the brain [50]. The minor allele frequency of this SNP in our sample was 22%; the HWE P-value was 0.231. The genome-wide P-values for this factor are shown in Figure 2C, and their distribution compared with its expectation under the null (obtained via permutations) is shown in Figure 2D. Differences in factor F1 for the three genotypes are shown in Figure 2E. We also examined the unprocessed phenotypic data stratified by genotype at this SNP and ran repeated measures ANOVAs to determine which individual phenotypes were associated with rs3784943 (Figure 2F). When performing dimension reduction on a complex dataset, it is critical to examine the impact of the SNP on the high-dimensional phenotypes rather than only the effect size on the one-dimensional factor.
