IGF1 and acute lymphoblastic leukemia: In this study, statistical adjustment for birth weight did not affect the associations observed for the significant risk haplotypes in IGF1, IGF2, and IGF2R, or the single nominally significant (p < 0.05) putative functional SNP in IGF1. The independence of the observed associations from birth weight, coupled with the absence of direct associations of the haplotypes and htSNP in question with birth weight (data not shown), suggests that the effects of the risk haplotypes and alleles on childhood ALL risk are not directly mediated by birth weight.