In a first study of its kind, a research team at Children's Hospital of Philadelphia (CHOP) have determined the association between genetic determinants of puberty timing and bone mineral density.
- People with the genetic factors responsible for delaying the average age of puberty are at an increased risk for low bone density.
- Low density bones make people more susceptible to diseases like osteoporosis and also recurrent bone fractures.
- Bone mineral density was found to be the lowest in the lower back and hip bones.
Delayed age of puberty corresponds with reduced bone density, reports the study published in the Journal of Bone and Mineral Research
Adolescence-the peak period of bone development
Adolescence is a period of peak bone development. It is crucial as majority of bone growth and development occurs during puberty. Since the spine is rich in trabecular bone it may be particularly affected by late puberty effects. Therefore, when puberty is delayed so is bone development leading to conditions like osteoporosis and bone fractures later in life.
The study was carried out to determine the association of the genetics that leads to delayed puberty
on bone density. Bone and growth measurements were taken over a period of 7 years from over 2,000 healthy children, adolescents and young adults for the Bone Mineral Density in Childhood Study at CHOP.
The study used two different approaches to study delayed puberty and bone density. The first was a genetic risk score that performed the association analysis of puberty-delaying effect estimates. The second is the Mendelian Randomization which determined the causal inference analysis.
‘While the relationship between delayed puberty age and lower bone density is more consistent in girls, boys with the genetic predisposition also have lower bone mineral densities.’
The genetic risk score (GRS) was generated based on the genetic mutations that predisposed children to delayed puberty and the relative bone mineral density.
The GRS for delayed puberty age was associated with lower bone density
in both boys and girls. The lowest density was observed in the lower back and hip bones.
Another analysis called the Mendelian Randomization was used to determine that delayed puberty caused lower bone density in adults.
A strong causal effect was also detected in young adolescent girls that reiterates that in fact delayed puberty does cause lower bone density. The causal effect was however not evident in the case of young adolescent boys.
"If an individual is genetically programmed for later puberty, we found that he or she tends to have lower bone mineral density during childhood as well as in adulthood," said geneticist Struan F. A. Grant, PhD, co-author of the study. References :
- Cousminer, D. L., Mitchell, J. A., Chesi, A., Roy, S. M., Kalkwarf, H. J., Lappe, J. M., Gilsanz, V.,Oberfield, S. E., Shepherd, J. A., Kelly, A., McCormack, S. E., Voight, B. F., Zemel, B. S. and Grant, S. F. (2017), GeneticallyDetermined Later Puberty Impacts Lowered Bone Mineral Density in Childhood and Adulthood. J Bone Miner Res. doi: 10.1002/jbmr.3320