Thirty or more genes are involved in determining when a girl reaches puberty, scientists from various countries wrote in the journal Nature Genetics, after scanning the genomes of over 100,000 females in Europe, US and Australia. Girls in several countries, including the UK and USA are entering puberty early, some as young as 10 years, the authors explain.
The study involved scientists from 104 worldwide institutions, part of the large International ReproGen Consortium.
Nobody is certain why puberty is occurring much earlier among females than it did 100 years ago. Some suggest it may be linked to obesity. The authors in this latest study agree that this is most likely.
They found that some of those 30 genes that were linked to the timing of puberty were also associated with body weight regulation and fat metabolism. Whether or not obesity is a consequence of something or a cause of early puberty is still not clear, the researchers stress.
The scientists add that their study did not reveal whether early puberty is affected by those genes, diet, lifestyle and other environmental factors, a combination of all, and if so which is the main player.
The findings from this study, and future ones that use information collected from it will eventually help prevent chronic health problems linked to excessive weight gain, the researchers believe. Early puberty not only increases the risk of obesity and female cancers later on in life, but also a number of other illnesses. A female with early puberty is more likely to experience poorer health during adulthood compared to other females.
The study investigators also identified specific genes that are involved in cell development and hormone regulation, demonstrating that puberty is controlled by a wide and complex range of biological processes.
Lead author Cathy Elks at the Medical Research Council (MRC) Epidemiology Unit in Cambridge, England, said:
- “It is interesting that several of the new genes for puberty timing have been linked in other studies to body weight gain and obesity. This suggests that females in some families may inherit a joint genetic susceptibility to weight gain and early puberty.”
Senior author Dr Ken Ong, also form the Medical Research Council (MRC) Epidemiology Unit, said:
- “We know that girls who are overweight are more likely to go through puberty at younger ages. Our findings tell us that being overweight and early puberty are intricately linked. It is also important to understand that these ‘common genetic factors’ can be modified by changes in lifestyle. If rates of childhood obesity continue to rise we will see many more girls reach puberty at young ages. Conversely, efforts to prevent or reduce childhood obesity will help avoid early puberty.”
Senior author Dr Anna Murray, University of Exeter, England, said:
- “Scientists have long been fascinated by how the body knows whether it has enough nutrient stores to launch into puberty which leads to reproductive maturation. We found that the timing of puberty is related to fatty acid metabolic pathways. There is evidence that the brain can sense these types of body fats.”
According to Dr Enda Byrne, from QIMR’s Queensland Statistical Genetics Laboratory, Australia:
- “Early puberty is a risk factor for a number of later life illnesses and poor health, including obesity and breast cancer.
There has been a gradual decrease in the average age of menarche in the population over the last century which has been attributed to improved child nutrition. It has also been known for some time that higher weight gain in childhood is associated with earlier puberty. The results from this study show that many of the genes that increase risk for weight gain and obesity in adulthood, also influence timing of puberty. This supports the idea that the body launches into puberty once it reaches a certain level of nutrient stores and therefore children who are overweight are more likely to undergo early puberty.
Our study identified genes involved in metabolism of fatty acids in the body as influencing timing of puberty. Some women inherit genes that make them more susceptible to weight gain and early puberty, but changes in lifestyle such as healthier eating and exercise can alter these genetic effects. One of the next stages of this study will be to test whether the same genes also influence timing of puberty in males.”
Over 100 scientists from the International ReproGen Consortium
Nature Genetics Published online: 21 November 2010 | doi:10.1038/ng.714
Written by Christian Nordqvist