Early puberty among boys is associated with shorter lifespans, according to a new genetic study by scientists at the University of Cambridge. 
Published this week in Nature Communications, the study also identified more than 76 genes and gene regions that influence the timing of puberty in boys.
BMI and Hair Color
Some of those genetic associations are also linked with measures of obesity, body mass index (BMI), and hair color. The study found that men with red, dark brown and black hair were more likely to have gone through puberty earlier than other men.
“The link between early puberty and shorter life expectancy may be partly explained by its negative impact on cardiometabolic health and diseases such as type 2 diabetes,” said co-first author Dr. Felix Day from the MRC Epidemiology Unit at the University of Cambridge. “If so, then finding ways to prevent early puberty could help.”
Puberty Timing in Men and Women
Day is part of a team of researchers who have been studying puberty timing both in men and women. Previous studies have found shared genetic associations between both sexes for the timing of puberty.
Traditionally it has been more difficult to study this life stage in boys. As such, most of our previous understanding of the genetic influence on puberty came from studies of women. Studying puberty in women and girls is often easier because it is often easier for a girl to recall her period. For boys remembering milestones that mark puberty like “voice breaking” is often harder to recall. A recent large-scale study of the DNA of 370,000 women identified 389 independent genetic associations. Those associations account for approximately one-quarter of the estimated heritability for puberty.
Longterm Health
Up until now, genetic studies of puberty timing in men are much fewer and smaller in scale. For this study, the scientists analyzed data from more than 200,000 men of European ancestry. To do that they included data mostly from the UK Biobank, but also data from 23andMe customers who consented to participate in research.
While the associations with BMI may in part explain the link with shorter lifespans, the link with hair color is less clear. Researchers believe the hair color association points toward a connection with a common set of hormonal regulators in the brain. Those regulators play a role in several different traits.
“Our most surprising finding was that some of the genes that regulate puberty timing in boys and girls also determine hair color,” said Dr. John Perry, a senior author of the paper who is also at the MRC Epidemiology Unit.
The finding highlights “an interesting common set of hormonal regulators in the brain that regulates both of these seemingly diverse traits,” Perry said.