Recently, common variants in LIN28B were associated with age at menarche in four independent genome-wide association studies (GWAS)8–11. LIN28B is a human homolog of lin-28 in C. elegans, which controls its rate of progression from larval stages to adult cuticle formation, indicating the possible conservation of specific micro-RNA regulatory mechanisms involved in developmental timing9. A second menarche locus was identified in an intergenic region at 9q31.28,10. These two loci together explained only 0.6% of the variance in age at menarche8. We anticipated that a much larger GWAS would substantially increase the yield of loci associated with age at menarche.
