With the current sample (TI ≤ 40, n = 76; TI > 40, n = 47; Controls, n = 29; COPD, n = 94), the minimal detectable absolute differences to achieve 80% power were ~25 percentage points for CHRNA3–nicotine dependence contrasts and ~11 percentage points for EPHX1–COPD. This evidence concerns the gene CHRNA3 and nicotine dependence.