Priority CommunicationMethylation Matters: Interaction Between Methylation Density and Serotonin Transporter Genotype Predicts Unresolved Loss or Trauma
Section snippets
Participants
The Iowa Adoption Studies are a long-standing series of studies on children (domestically) adopted in the first few months after birth into middle-class families. Biodata were collected in the last round of data collection since 2004 (17). Here we use data from predominantly Caucasian (91%) adoptees who completed the AAI and for whom genotyping of the 5HTTLPR locus and methylation measures were available (n = 143; 50% females; mean age 39 years, SD = 7.32). All procedures were approved by the
Results
The results of the analysis of variance of unresolved loss or trauma with gender and 5HTTLPR genotype (ss, sl, ll) as factors and depression and methylation density as covariates are presented in Table 1. No significant main effects were found. The interaction between 5HTTLPR and promoter methylation significantly predicted scores on unresolved loss or trauma, F(2,121) = 4.87, p = .009, partial η2 = .08. Similar results were found when we controlled for age and when we included the
Discussion
In this study on participants with experiences of loss or other traumatic events, the 5HTTLPR genotype association with unresolved state of mind was dependent on methylation density. As expected, the long variant in combination with high methylation levels of the 5HTT promoter associated CpG islands predicted more unresolved loss or trauma. Methylation of alleles carrying the ll 5HTT variant seemed to hamper the expression of the otherwise protective ll variant (17) and to elevate the risk of
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