For chromosomes 11q23 we identified three haplotype-blocks (Figure S3 in Supplement 1). Significant differences in haplotype frequencies between smokers and non-smokers were found only in Block-2 (Table 3). Haplotype AAGGGAAAAGGGACGGGA appeared to be protective with stronger effect at age 14 than 31. In the same block, haplotype GGGGAGGGAGAGGAGGGG was associated with increased risk of smoking at age 14 but not 31.
