The chromosome 10 SNPs represented a single signal (Supplemental Figure S6), so follow-up analyses used a representative locus. Controls (N=6,435) included individuals who did not meet criteria for DSM-IV cannabis dependence but may have met criteria for a lifetime history of DSM-IV cannabis abuse or endorsed 1–2 dependence criteria. Exclusion of individuals with abuse (N=1,590) from among the controls yielded similar effect sizes but diminished statistical significance, likely due to the reduced statistical power (rs7098706: b = −0.53, p = 5.90E-7; rs1409568: b = −0.50, p = 1.21E-6). Excluding control individuals with abuse or 1–2 dependence criteria (N=2,152) had a similar effect (e.g., rs7098706 b = −.50, p = 1.85 E-6; rs1409568: b = −0.48, p = 3.95E-6). Thus, heterogeneity within the control population is not responsible for the observed association.
