Transcription hotspots identified by linkage and association scans. Linkage, the numbers of times that a SNP has LOD > 1.44 (nominal p-value = 0.01) for a transcript were counted and plotted as black vertical lines. Association, the numbers of times that a SNP is one of the top 30 association SNPs for a transcript were counted. The SNP-by-SNP transcription hotspots pattern is noisy. To have a clear pattern, these counts were aggregated into bins of ≤5 cM by chromosomes as in Morley et al. . Bins with ≥5 genetic regulators identified (p = 4 × 10-3) were identified as eQTL hotspots (blue dotted lines are the selection thresholds).