Parts A-B: (A) Quantile-Quantile (QQ) plot and (B) Manhattan plot for the genome-wide association analysis of the age at onset of DSM-IV alcohol dependence in COGA (a) Observed p values for the 4,058,415 SNPs (black dots) were plotted against the expected p value (x--axis). The genomic inflation factor value (lambda) was 1.037.(b) Observed log p values for the 4,058,415 SNPs were plotted according to chromosomal position.
