al., 2006; Gelernter et al., 2007), short-term cessation (Swan et al., 2006), and maximum cigarettes smoked in a 24-hour period (Saccone et al., 2007a). Suggestive linkage has been reported at multiple locations across the genome, but with most LOD scores not exceeding 3.0 and indeed most samples used were not selected for informativeness for cigarette smoking, with a few notable exceptions: 1) quantity smoked: LOD = 4.17 on chromosome 10 (Li et al., 2006), 2) short-term cessation: LOD = 4.0 on chromosome 16 (Swan et al., 2006), and 3) maximum cigarettes consumed in 24-hours: LOD = 5.98 on chromosome 22 (Saccone et al., 2007a). Each of these latter three studies included samples that were ascertained for smoking-behavior and reported LOD scores for cigarette smoking phenotypes greater than 3.0. Of note, only one linkage study to date has reported findings on nicotine withdrawal, and found the highest peak for withdrawal symptoms on chromosome 6 (LOD = 2.7; Swan et al., 2006).
