Figure 3
From: A genome-wide association study for late-onset Alzheimer's disease using DNA pooling
Plot of combined Z-test p-values against chromosomal location for pooled data. Out of 561,494 SNPs that were genotyped in our case – control pools, only 3 would have remained significant after Bonferroni correction for multiple testing, two of these SNPs are near the APOE gene on Chromosome 19. For a genome-wide association study on 500,000 markers (assuming that markers are independent) the significance level is 10-7. The line of genome-wide significance is plotted therefore at this level, although the combined Z-statistic provides only an approximation of the p-values produced from individual genotyping.