Fig. 4

The association between follow-up time and principal components in similarly differentially expressed genes. Controls are shown in black, cases in red. Follow-up time in cases represents the time to diagnosis in days. Included genes are similarly differentially expressed in the prediagnostic study and the meta-analysis of clinical studies (groups ‘++’ and ‘--’). The first four principal components explained respectively 26.9, 16.5, 6.0 and 5.6%. When components were included in a linear model as the dependent variable, the time to diagnosis (in cases) showed a statistically significant association for PC1 (−1.55 × 10–3) and PC2 (−1.45 × 10–3) with respective p values of 0.023 and 0.007. Associations for PC3 and PC4 were not statistically significant