Research Paper Volume 7, Issue 2 pp 110—122

Figure 7. Age-correlated regulation of DNA-repair genes. (A) Heatmap of significant age-associated changes in genes associated with DNA-repair. The heatmap depicts all genes that are significantly changing with age according to a robust linear regression (p-value < 0.1, R² > 0.4). The gene list is compiled from 405 genes annotated with DNA repair processes. Depicted expression values are gene-wise mean centred and scaled to unit variance across all samples and hierarchically clustered using complete linkage. Four donors from the middle aged group having a large body mass index and being outliers in the PCA (Fig.1A) have been excluded from the analysis. (B) Signal intensities of Agilent array probes representing Ligase 4 (closed circles) and XRCC4 (open circles) plotted over calendar age of the donors. Signal intensities were quantile normalized across all samples and input data were subjected to baseline transformation to the median of all samples. Results of linear regression are stated as R²: fraction of variance explained by the linear model, p: probability for slope = 0.