“Puberty in girls normally occurs between the ages of 10 and 15, but it has been occurring earlier and earlier in recent decades – although it is not entirely clear why. Early puberty is associated with an increased risk of conditions later in life, such as type 2 diabetes, cardiovascular disease and some cancers, while later puberty is linked to better adult health and longevity.”
What makes a girl reach puberty earlier or later? A new study, “the largest of its kind to date”points out the potential role played by certain genes, which can affect the timing of puberty and in particular increase the risk of early menstruation.
Genetic variants affect puberty by accelerating weight gain
As part of their work, published in the journal Nature Geneticsresearchers from the Medical Research Council (MRC) at the University of Cambridge in the UK analysed the DNA of some 800,000 women from Europe, North America, China, Japan and Korea. They found more than 1,000 genetic variants (small changes in DNA) that influence the age of menarche, including around 600 observed for the first time.
“Just under half (45%) of them affected puberty indirectly, by accelerating weight gain in infants and young children,” scientists point out that weight gain during early childhood is “a risk factor for precocious puberty”. Precocious puberty which can, in turn, “lead to potentially serious health problems later in adulthood, such as overweight and obesity.”
Other, rarer genetic mutations appear to have significant effects on puberty. For example, the study found that one in 3,800 women carried variants of the ZNF483 gene, leading them to experience puberty an average of 1.3 years later.
Identify girls whose puberty will come very early or very late
Furthermore, the researchers were able to predict, by developing a “genetic score”, whether a girl was likely to reach puberty very early or very late. Girls with the highest genetic score (the first percentile) were 10 times more likely to have extremely delayed puberty, that is, after the age of 15. Conversely, girls with the lowest genetic score (the last percentile) were 14 times more likely to reach puberty early, before the age of 10.
“In the future, we may be able to use these genetic scores in the clinic to identify girls whose puberty will come very early or very late,” conclude the authors.
