Girls who are overweight in childhood may be at greater risk of precocious puberty, genetic research reveals.
In the largest study of its kind to date, a team from the University of Cambridge studied the DNA of around 800,000 women from around the world.
They discovered more than 1,000 variants (small changes in DNA) that influence the age at which girls start their first period.
Just under half of these variants affected puberty by increasing weight gain in early childhood.
The age at which girls reach puberty and start having periods usually occurs between the ages of 10 and 15, although this has become increasingly earlier in recent decades.
Researchers at the University of Cambridge discovered more than 1,000 genetic variants that influence the age at which girls start getting their first period. Almost half of these variants affected puberty by increasing weight gain in early childhood
The greatest risk begins in those under 13 years of age at the time of menarche and increases the younger they are. Experts believe this could be due to higher levels of estrogen, which they are exposed to for longer.
Doctors have not been able to identify a single or even a handful of causes for precocious puberty, although experts told DailyMail.com that some underlying factors include obesity, stress and genetics.
Early puberty is linked to an increased risk of a range of diseases in later life, including type 2 diabetes, cardiovascular disease and certain cancers.
Previous studies have already shown that overweight is related to early puberty in both boys and girls.
Professor John Perry, one of the study’s authors, said: “Many of the genes we found influence early puberty by first accelerating weight gain in infants and young children.”
‘This can lead to potentially serious health problems later in life, as early puberty leads to higher rates of overweight and obesity in adulthood.’
The researchers also generated a genetic score that predicted whether a girl was likely to hit puberty very early or very late.
Girls with the top 1 percent of this genetic score were 11 times more likely to have extremely late puberty, after age 15.
Furthermore, girls with the lowest 1 percent genetic score were 14 times more likely to have extremely early puberty, before age 10.
Lead author Professor Ken Ong said: ‘In the future, we will be able to use these genetic scores in the clinic to identify those girls whose puberty will come very early or very late.
‘The NHS is already trialling whole genome sequencing at birth, and this would give us the genetic information we need to make this possible.
‘Children who come to the NHS with very early onset of puberty (aged seven or eight) are offered puberty blockers to delay puberty.
‘But the age of puberty is a continuum, and if they don’t reach that threshold, we have nothing to offer them.
‘We need other interventions, whether it’s oral medication or a behavioural approach, to help. This could be important for their health when they get older.’
The study’s lead researcher, Dr Katherine Kentistou, added: “The new mechanisms we describe could form the basis of interventions for people at risk of precocious puberty and obesity.”
Previous work by the team showed that a receptor in the brain, known as MC3R, senses the body’s nutritional status and regulates the timing of puberty and growth rate in boys.
Other genes identified appeared to act in the brain to control the release of reproductive hormones.
The findings were published in the journal Nature Genetics.
