INDIANAPOLIS — More than 160 institutions were involved in an international project, published today in the journal Nature, proving that the age at which girls reach sexual maturity can be influenced by either parent. This is the first time it has been shown that imprinted genes — a process of temporarily silencing the genes of one parent — can control the rate of development after birth.
The findings come from an international consortium study involving scientists from 166 institutions worldwide, including Indiana University. The researchers identified 123 genetic variations that were associated with the timing of when girls experienced their first menstrual cycle by analyzing the DNA of 182,416 women of European descent from 57 studies.
Indiana University genetic epidemiologist Chunyan He, Sc.D., is one of the 10 lead authors of the consortium article. A member of the Indiana University Melvin and Bren Simon Cancer Center and an assistant professor at the IU Richard M. Fairbanks School of Public Health, Dr. He’s research for this paper was made possible by the Komen Tissue Bank at the IU Simon Cancer Center, the only bank of normal breast tissue in the world.
Dr. He said 300 healthy tissue samples from the Komen Tissue Bank and 300 samples of malignant breast tissue from the IU Simon Cancer Center Tissue Procurement and Distribution Core were genotyped and analyzed for the data she contributed to the Nature article. This is one of the largest studies using Komen Tissue Bank samples to date, she said. The one-of-a-kind healthy tissue bank at IU was established in 2005 and supported by Susan G. Komen since 2007. Nearly 10,000 women have contributed healthy blood or breast tissue to aid research into the causes of and treatments for breast cancer. Anna Maria Storniolo, M.D., is executive director of the Komen Tissue Bank at the IU Simon Cancer Center.
Dr. He is the seventh author in the list of 204 co-authors for this unique, large-scale collaborative effort to produce scientific findings relevant to cancer researchers and specialists studying other diseases.
“Age of menarche is a marker of timing of puberty in females,” the Nature article states. “It varies widely between individuals, is a heritable trait and is associated with risks for obesity, type 2 diabetes, cardiovascular disease, breast cancer and all-cause mortality.”
“This study is a great example of team science research in genetic epidemiology,” Dr. He said.
The mechanisms that determine puberty’s onset remain unclear, Dr. He said. But these findings indicate that hundreds of variants are involved in the timing and point to other mechanisms that may be associated with the timing of puberty and higher risks of adult diseases.
The activity of imprinted genes differs depending on which parent the gene is inherited from; some genes are only active when inherited from the mother, others are only active when inherited from the father. Both types of imprinted genes were identified as determining puberty timing in girls, indicating a possible biological conflict between the parents over their child’s rate of development.