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Scientists are cracking puberty's genetic code

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The timing of a woman's first period is way more complex than we thought

Philippe Put / Flickr

Humanity is one step closer to understanding what triggers all the mysterious changes that take place in women during puberty. By looking at genetic variants in over 180,000 women of European descent, an international group of researchers was able to pinpoint which regions of our DNA contribute to the timing of puberty. This, they say, is crucial to our understanding of health problems like Type 2 diabetes and breast cancer, because the timing of a woman’s first period has been linked to both.

"We identified over 100 regions of the genome that were associated with puberty timing," said John Perry, lead author of the study published in Nature today and a geneticist at the University of Cambridge, in an email to The Verge. "However our analyses suggest there are likely to be thousands of variants and possibly genes involved in a broad range of biological pathways and processes." These results, Perry said, means that the factors that influence the timing of a woman's first period are much more complex than scientists and doctors originally thought.

one parent might have a stronger influence on their daughter's puberty

Another noteworthy finding comes by way of our imprinted genes — genes in which the copy from one parent is silenced in favor of the copy that came from the other parent (meaning that they don't produce a hybrid effect). The researchers found that these genes play an important role in puberty among women, which means that within a family, one parent might actually have a much stronger influence on their daughter's puberty than to the other. "Until now, imprinted genes were largely thought to be only important for growth and development in babies before birth," Perry said, "however our study supports the idea that these genes continue to play a role in later life health and disease."

But the study doesn't offer all the answers. For one thing, Perry said the number of women they included in the study limits their ability to determine exactly which genes are involved, and how. "Our results indicate that it’s likely millions of women would need to be included to successfully identify a significant fraction of all puberty genes that are likely to exist," he explained. "However, we hope the genes we have identified so far should provide significant insights into reproductive biology with the aid of further studies."

Another possible issue is that only data from women with European backgrounds were used in the study. Women of different ancestral backgrounds might display some variation in individual genetic variants, Perry said. But the researchers are planning to study women of different backgrounds as well, and Perry thinks the underlying genes and biological processes will remain the same across populations.

50 percent nature, 50 percent nurture

Finally, it’s important to note that when it comes to puberty, genes aren’t everything. The timing of a women’s first period is actually 50 percent nature and 50 percent nurture. This means that environmental factors — things like nutrition, family stressors, and physical activity — also have a strong influence on the timing of a woman’s first period.

Still, given that women who experience puberty at younger ages have a higher risk of developing Type 2 diabetes, cardiovascular disease, and breast cancer, these findings are important. If scientists can figure out why one woman started buying tampons when she turned nine, whereas another only had to buy them at 14, we might gain a better understanding of the underlying biology behind various life-threatening diseases — as well as the approaches that could stop them from occurring in the first place.