Figure 2.

The top signal associated with the Nicotine Metabolite Ratio in African ancestry females and males was found on chromosome 19 in the region containing CYP2A6. The nicotine metabolite ratio was rank-transformed for analysis. Regional plots were generated using LocusZoom⁴⁴ (freely available at locuszoom.org). In African American (AA) females, the top variant was rs11878604 (a), which was also significant in AA males. The influence of rs11878604 on the Nicotine Metabolite Ratio (NMR) in AA females is shown in (b). In AA males, the top variant was rs3865454 (c), which was also significant in AA females. The influence of rs3865454 on the NMR in AA males is shown in (d). Note: in AA females, there was a second independent signal on chromosome 19: the top variant was an indel at position 41352257 (P = 8.3e−9, after conditioning on rs11878604); this variant was also GWS in AA males. Linkage disequilibrium patterns in (a) and (c) are based upon the hg19/1000 Genomes November 2014 release African reference population. The plots in (b) and (d) were created using SPSS version 23 (can be purchased from IBM, Armonk, New York, USA). The black horizontal line represents the mean rank-transformed NMR in each group, and the P-value is from the GWAS after adjusting for population substructure and NMR covariates.