We analyzed 92 SNPs falling in a 347-kb interval that spanned FTO (data are available from the authors at http://medschool.umaryland.edu/endocrinology/afdspublic.asp). Of these SNPs, 26 were associated with BMI (P=.04 to <.001 under an additive genetic model). rs9939609, the associated SNP originally reported by Frayling et al,1 was modestly associated with obesity (P =.03) and not associated with BMI (P=.06) in the OOA, although stronger associations with this SNP were seen with total fat mass (P = .007) and percentage of body fat (P = .01). Figure 1 shows 20 SNPs in the region surrounding rs9939609. These 20 SNPs all fall within an 81-kb region spanning from within intron 1 to within intron 3 of the FTO gene. The SNP most strongly associated with BMI in the OOA was rs1861868, a common SNP with a similar risk allele frequency (0.47) as in HapMap (http://www.hapmap.org) genotype samples of white individuals (0.50). Each A allele of rs1861868 was associated with a 0.75 increase in BMI (P<.001), corresponding to a mean (SD) increase in weight of 2.0 (0.7) kg per allele (Table 1). Individuals
