To identify loci that might increase susceptibility to a specific smoking behavior trait, we performed subgroup GSMA over the genome scan results on the smoking behaviors measured by FTND and MaxCigs24. Five genome scan results were included in the analysis of FTND (1347 families with 3995 subjects). The weighted and unweighted PSR for all bins across the genome are illustrated in Figure 2. There were no regions that achieved genomewide significant or suggestive evidence for linkage, except six regions showed nominally significant evidence for linkage in the weighted analysis (Table 3). In the subgroup analysis of MaxCigs24, four genome scan results, all from European ancestry populations, were included (966 families with 3273 subjects). The genomewide results with weighted and unweighted analysis are illustrated in Figure 3. A genomewide significant linkage was identified in 20q13.12–q13.32 by both weighted (PSR=0.00041, POR=0.048) and unweighted analysis (PSR=0.00032, POR=0.037). Three regions (22q12.3–q13.32, 20p12.1–q13.12 and 17q24.3–q25.3) achieved genomewide suggestive evidence for linkage. Eleven regions on six chromosomes (2, 12, 16, 17, 20 and 22) with both PSR and POR less than 0.05 are somewhat likely to harbor risk loci for MaxCigs24 trait (Table 4).
