Prospects for epigenetic research within cohort studies of psychological disorder: A pilot investigation of a peripheral cell marker of epigenetic risk for depression
Section snippets
Participants and design
Adolescent participants (N = 150, 83 male), with and without a history of depression, were sampled from an established life course study of adolescent health and development (Victorian Adolescent Health Cohort Study, VAHCS). The VAHCS is a population representative sample of 2032 young Australians living in the state of Victoria who have been followed across 8 waves since 1992. The cohort was initially defined with a two-stage cluster sample in which we selected two Year 9 classes at random from
Results
The average methylation level across the entire CpG Island was 6.3% (95% confidence interval (CI) 5.8–6.8, range 2.9–22%). Table 1 shows methylation levels for each of the 36 CpG units assayed among those reporting no depressive symptoms and those reporting persistent depressive symptoms during adolescence.
Principal factor analysis (PFA) was used to explore possible sub-regions within the 5HTT CpG Island defined by co-variation in methylation levels between CpG units. PFA identified eight
Discussion
Depressive symptoms during adolescence were not associated with buccal cell methylation of the entire 5HTT promoter or within sub-regions of the promoter defined by Factor Analysis. Depressive symptoms were likewise not associated with 5HTTLPR genotypes. Carriers of the 5HTTLPR s-allele who had the highest level of 5HTT buccal cell methylation within one sub-region of the promoter (denoted F1) did have an elevated risk for depression. However, until replicated in appropriately powered studies,
Acknowledgements
The authors would like to thank Prof. Glenn Bowes, Prof. Robert Williamson, Menrnoush Lotfi, Philip Greenwood, and Dr. Sue Forrest for their valuable contributions to this research. We acknowledge contributions of Drs. Richard Saffery and Jeffrey Craig as joint senior authors. This work is supported by the following Australian scientific funding organizations: (1) the Victorian Health Promotion; the National Health and Medical Research Council, and; The Colonial Foundation.
We report no
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