Each SNP that reached genome-wide significance explained only a small fraction of the overall phenotypic variation in ‘age at first tooth’ (0.05–1.14%, ALSPAC; 0.06–1.45%, NFBC1966) and ‘number of teeth’ (0.09–0.94%, ALSPAC; 0.03–0.92%, NFBC1966). Pooling together the effects of the top SNPs at the genome-wide significant loci (Table 1) into a single allelic score explained 6.06% of the overall phenotypic variation in ‘age at first tooth’ and 4.76% of the variation in ‘number of teeth’. We also report loci displaying suggestive levels of association (Supplementary Material, Tables S1 and S2), 5 × 10−6 > P > 5 × 10−8, which included SNPs in the TMEM9 region that were reported as genome-wide significant in the study of secondary dentition by Geller et al. (7).
