Those who are genetically predisposed to begin puberty at a later-than-average time may have lower bone density, especially in their lower spine, which may increase their risk for osteoporosis and bone fractures later in life, according to researchers.

“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,” says geneticist Struan F. A. Grant, PhD, from Children’s Hospital of Philadelphia (CHOP).

The study, co-led by Grant, included data from the NIH-funded Bone Mineral Density in Childhood Study (BMDCS), and was published recently in the Journal of Bone and Mineral Research.

The BMDCS included sophisticated bone and growth measurements during annual visits for up to 7 years in over 2,000 healthy children, adolescents and young adults during 2002 to 2010, per a media release from Children’s Hospital of Philadelphia.

In the current research, the study team used a relatively new tool called a “genetic risk score” (GRS), which enables collective study of a group of genetic variants in one go.

“We generated a genetic risk score in the BMDCS study based on hundreds of genetic variants associated with later puberty in children, and looked for associations with bone mineral density measurements,” states first author Diana Cousminer, PhD, a CHOP geneticist with expertise in the genetics of puberty.

The researchers performed these analyses separately in boys and girls, and also in publicly available corresponding genetic data on bone mineral density in adults, the release explains.

For both boys and girls, the GRS for later puberty associated with lower bone mineral density in both a longitudinal cohort of 933 individuals who each had up to seven assessments, and in a cross-sectional cohort of 486 individuals. The results varied according to the part of the skeleton where bone mineral density was measured, with lowest density in the lower back and hip bones.

In a separate analysis called “Mendelian Randomization,” the study team found that later puberty caused lower bone mineral density in both adult men and adult women. They also detected a strong causal effect in adolescent girls, while finding no causal relationship for adolescent boys.

Cousminer notes in the release that the number of boys in their analysis may not have been large enough to show a significant effect, the release continues.

“Now that we are aware of the risks to lifelong bone health if someone is genetically predisposed to later puberty, we can work on strategies such as promoting weight-bearing physical activity, to optimize bone density during skeletal development,” shares co-study leader Babette S. Zemel, PhD, principal investigator of the BMDCS at CHOP, where she directs the Nutrition and Growth Laboratory, per the release.

[Source(s): Children’s Hospital of Philadelphia, Science Daily]