A large collaboration of researchers across 166 research centres studied the genomes of 182,416 women and the age at which they reached their first period. The scientists discovered associations with multiple genomic regions, indicating that genetic factors play an important role in the age of puberty, in addition to known environmental factors.
'There is a remarkably wide diversity in puberty timing - some girls start at age eight and others at 13', said Dr Ken Ong from the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge and senior author of the study. 'While lifestyle factors such as nutrition and physical activity do play a role, our findings reveal a wide and complex network of genetic factors', he said.
Understanding the timing of puberty is important because it can influence the risk of developing certain disorders later in life. Dr Ong said, 'We are studying these factors to understand how early puberty in girls is linked to higher risks of developing diabetes, heart disease and breast cancer in later life — and to hopefully one day break this link'.
Many of the regions of DNA that were identified in this study were found to be located in imprinted regions of the genome. Usually, both copies of a gene (one from the mother and one from the father) are equally active; however, in imprinted regions of DNA, genes from only one parent are expressed, while genes from the other are silenced.
Lead author of the study, Dr John Perry from the MRC Epidemiology Unit at the University of Cambridge, said: 'Our findings imply that in a family, one parent may more profoundly affect puberty timing in their daughters than the other parent'.
This is the first study to show an effect of imprinted genes on development after birth. Dr Perry said, 'We knew that some imprinted genes control antenatal growth and development — but there is increasing interest in the possibility that imprinted genes may also control childhood maturation and later life outcomes, including disease risks'.
Many of the genes identified have known links to puberty, and the study also identified genes involved in regulating body weight, and implicated in rare pubertal disorders as being important for the timing of puberty.
A co-author of the study Dr Anna Murray, from the University of Exeter Medical School, commented, 'We found that there are hundreds of genes involved in puberty timing, including 29 involved in the production and functioning of hormones, which has increased our knowledge of the biological processes that are involved, in both girls and boys'.