The age where girls reach sexual maturity is affected by ‘imprinted’ genes, a small sub-set of genes whose activity differs depending on which parent passes with that gene, according to new research published now within the journal Nature.
The findings originate from an international study in excess of 180,000 women involving scientists from 166 institutions worldwide, such as the University of Cambridge. They identified 123 genetic variations that were linked to the timing of when girls experienced their first menstrual cycle by analyzing the DNA of 182,416 women of European descent from 57 studies. Six of those variants were found to become clustered within imprinted parts of the genome.
Lead author Dr. John Perry in the Medical Research Council (MRC) Epidemiology Unit, University of Cambridge says: “Normally, our inherited physical characteristics reflect a roughly average combination of our parents’ genomes, but imprinted genes place unequal weight around the influence of either the mother’s or the father’s genes. Our findings imply that inside a family, one parent may more profoundly affect puberty timing within their daughters compared to other parent.”
The activity of imprinted genes differs depending on which parent the gene is inherited from C some genes are just active when inherited from the mother, others are only active when inherited in the father. Both types of imprinted genes were identified as determining puberty timing in girls, indicating a potential biological conflict between the parents over their child’s rate of development. Further evidence for the parental imbalance in inheritance patterns was obtained by analyzing the association between these imprinted genes and timing of puberty inside a study of over 35,000 women in Iceland, for whom detailed information on their own genealogy were available.
This may be the first time that it has been shown that imprinted genes can control rate of development after birth.
Dr. Perry says: “We knew that some imprinted genes control antenatal development and growth C but there is increasing curiosity about the chance that imprinted genes may also control childhood maturation and later life outcomes, including disease risks.”
Senior author and pediatrician Dr. Ken Ong at the MRC Epidemiology Unit says: “There is a remarkably wide diversity in puberty timing C some girls start at age 8 yet others at 13. While lifestyle factors for example nutrition and physical activity do play a role, our findings reveal a large and sophisticated network of genetics. We’re studying these factors to know how early puberty in girls is linked to higher perils of developing diabetes, cardiovascular disease and cancer of the breast in later life C and to hopefully one day break this link.”
Dr. Anna Murray, a co-author from the University of Exeter School of medicine, adds: “We found that you will find hundreds of genes involved with puberty timing, including 29 involved in the production and functioning of hormones, which has increased our knowledge of the biological processes which are involved, in both kids.”
The study was supported in the UK by the Medical Research Council and also the Wellcome Trust.