Age at menarche (first period) and natural menopause (last period) are heritable traits. The timing of puberty is thought to alter risk of several cancers, and knowledge of the genetics of these traits may help understand why. So far, hundreds of simple forms of genetic variation have been identified but even collectively these only explain part of the heritability of age at merarche and menopause. Copy number variations (CNVs) are a more complex form of genetic association which are associated with common diseases and traits, and may account for some of the missing heritability. This project aims to analyse the role of copy number variation in age at menarche and natural menopause for an international consortium called REPROGEN.