A new study published in the journal Nature revealed that the timing of a girl's menarche is influenced by several genes, possibly thousands of gene variations.
The researchers suggest that these findings may help understand how the timing of a girl's first period is linked to health problems in later life. Lead researcher John Perry, a senior scientist at the University of Cambridge MRC epidemiology unit in the United Kingdom, said, "We hope that with the help of future studies, this will in turn lead to better understanding of the underlying biology behind diseases such as type 2 diabetes and breast cancer." The role of estrogen levels in the development of the diseases were previously evaluated, but a clear link between menarche and health conditions later in life could not be established.
Data on 180,000 women were analysed by scientists from 166 institutions, and they found that the timing of puberty varied among different girls. While some matured as early as 8, others hit puberty in high school. This was dependent on several factors including nutrition, exercise, and body weight, among other things.
Perry said, "We identified over 100 regions of the genome that were associated with puberty timing. However, our analyses suggest there are likely to be thousands of gene variants -- and possibly genes -- involved." Perry pointed out that puberty timing was much more complicated than they previously thought it to be.
Dr Patricia Vuguin, a pediatric endocrinologist at Cohen Children's Medical Center in New Hyde Park, N.Y., stated that many of the genes that they found to be associated with puberty were completely new and have never been associated with puberty before. She was not involved in the study.
She also threw light on the early puberty cases which was not so common in the past, and until now, rising obesity was seen as the cause. But the study gave a whole new explanation to previously held concepts. Parents, she said, believed that a right, nutritional diet is the key to ensure "healthy" age puberty among the girls.
"But this study is saying, it's not that simple. It's not only about body fat, or about what you eat. It's much more complicated than that," Vuguin said.
According to Perry, the most astounding and biggest discovery is that a "special set" of genes known as imprinted genes may help govern the time of menarche. He explained that most of our genes are inherited from our parents, "one copy from each" and these copies from both parents are active. The imprinted genes on the other hand are different. Only one copy is active while the other is "silent".
"Our study supports the idea that these genes continue to play a role in later-life health and disease," Perry said.