Epigenetic mechanisms such as methylation may be very important in human disease, especially for diseases of older ages. Yet studies documenting epigenetic changes over the human lifespan, the vulnerability of epigenetic marks to environmental exposures, and the subsequent effects on human disease have been limited due to the absence of technical and biosample resources. A team has been assembled with the technology and resources to measure changes in methylation over time in the same individual for the purpose of examining a relationship between exposure and such changes, and assess the relationship between methylation and disease, by combining the epigenetic and epidemiologic expertise at Johns Hopkins with the resources of colleagues at the Icelandic Heart Association (IHA). The IHA has followed over 18K participants of the Reykjavik Heart Study since 1967 and has recently collected extensive cardiovascular and functional measures on 5758 of the surviving cohort as part of the AGES-Reykjavik study. Of these, 638 participants have DNA samples available for epigenetic measurement from two visits spanning 15 years, allowing for measurement of epigenetic changes over time in the same individual, which must occur if environment can influence epigenetic marks, but has never been directly observed in a human population. In addition, diet and smoking data and serum samples are available since 1967 as well as recent phenotype measures and disease outcomes for all 5758 AGES participants (2004-2005).
The specific aims i nclude assessing the: (1) Impact of environmental factors including dietary fish intake, serum folate levels, and smoking on inter-individual changes in whole-genome and candidate-gene specific methylation spanning 15 years;(2) Relationship between 15-year changes in methylation and subsequent disease-related quantitative measurements such as blood pressure, BMI, central adiposity, and coronary calcification;(3) Cross-sectional relationship between urinary cadmium (Cd) and candidate gene methylation;and (4) Cross-sectional relationship between candidate gene methylation and disease outcomes including CVD and cancer. This unique resource and team allows the first opportunity for longitudinal epigenetic measurement over 15 years in the same people, and connection of these epigenetic measurements to dietary and smoking exposures, as well as to cancer and cardiovascular disease consequences.
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