"On your 50th birthday, you would have 50 of these sites [from the subset of 749] that have acquired methyl groups in each cell," Xu said. "The longer you live, the more methylation you will have."
For future work, Xu and Taylor want to examine more samples, using a newer microarray that will explore methylation at 450,000 genomic methylation sites. The additional samples and larger microarray, which will provide 16 times more genomic coverage, will allow them to address whether environmental exposures during adulthood or infancy affect methylation profiles. These additional studies will help scientists better understand why methylation happens as people march toward their retirement years.
DNA methylation is one of several epigenetic mechanisms that can control gene expression without changes in DNA sequence. This study is part of a broader research effort, funded by NIEHS, to understand how environmental and other factors affect epigenetic mechanisms in relation to health.
Reference
Xu Z, Taylor JA. 2014. Genome-wide age-related DNA methylation changes in blood and other tissues relate to histone modification, expression, and cancer. Carcinogenesis; doi:10.1093/carcin/bgt391 [Online 28 November 2013].
Editor's Note:
What is the Sister Study?
The Sister Study is conducted by the National Institute of Environmental Health Sciences, one of the National Institutes of Health, of the US Department of Health and Human Services. From 2004 to 2009, more than 50,000 women across the US and Puerto Rico, who were between ages 35–74 and whose sister had breast cancer, joined this landmark research effort to find causes of breast cancer. Because of their shared environment, genes, and experiences, studying sisters provides a greater chance of identifying risk factors that may help us find ways to prevent breast cancer.
The Sister Study is currently tracking the health of women in the cohort. Participants complete health updates each year, as well as detailed questionnaires about health and experiences every two-to-three years. Research in the Sister Study focuses on causes of breast cancer and other health issues in women, as well as on factors that influence quality of life and outcomes after a breast cancer diagnosis.
Sister Study Participants Characteristics
Participants under age 50 at enrollment |
28% |
|
Participants with education of high school or less |
15% |
|
Participants with low income |
5% |
|
Participants whose mother had breast cancer |
19% |
|
Participants with an early age of menarche (<12) |
20% |
|
Participants who were postmenopausal at enrollment |
64% |
For more detailed tables on participant characteristics, please go to the Detailed Tables page.
Sister Study Participants by Geographic Distribution
Looking for a specific state? Go to the Geographic Distribution by State page.
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