(273 cases and 858 controls), who passed quality control, had complete DSM-IV and covariate data available, and met our case/control definitions: see Table 1. We also conducted a sensitivity analysis in which we increased the number of dependence symptoms from 1 to 3 to define a case, matching the threshold for a diagnosis but reducing sample size. Consistency of effect across the number of symptoms required, despite lower sample size and power, would support the conclusion that SNPs associated with any illicit drug abuse in the discovery analyses that replicate in GAIN are generalizable to clinical phenotypes such as DSM-IV.
