Figure S1. Q-Q plots for post-RT pain. This figure shows the quantile-quantile plots of observed versus expected p values on the â log10 scale, showing the conformity of the observed results to expectations under the null. Black lines indicate the distribution of observed p value versus expected p value, and red lines indicate the null distribution. Lambda confirms appropriate control of population substructure; (a) 1.649 before adjustment, (b) 1.017 after adjusting for population substructure with the first 3 PCs, and (c) 1.016 after further adjusting for all potential confounders identified in Table 1. PCs: principal components. (DOCX 32 kb)