Eczema is an allergic disease which affects the skin of thousands of children worldwide. EWAS analyses on related atopic factors such as asthma and Immunoglobulin E have already been carried out, as has a GWAS on eczema.
Epigenetic analyses were conducted to look at the relationship between DNA methylation and eczema. Avon Longitudinal Study of Parents and Children (ALSPAC) was used, which consisted of questionnaires about eczema status and methylation data at time points birth, age seven and age 15/17. In order to see if there was a relationship between methylation and whether a child had ever had eczema, I conducted a longitudinal study, and a cross-sectional study looking at the relationship between DNA methylation and whether a child had had eczema in the last 12 months. I adjusted for sex, surrogate variables, two socioeconomic status variables, maternal history and cell counts. I looked at environmental and genetic risk factors, including smoking, animal exposure and breastfeeding and mQTL’s to investigate DNA methylation as a potential mediator.
25 CpG sites were found to be suggestively associated at P<0.05 with the presence of eczema. There were five CpG sites which showed continued association between the different timepoints, strengthening the findings. There were 24 CpG sites which had a similarly small p-value when looking at the association between risk factors and eczema, and eczema and risk factors. These methylation sites were identified in smoking, but none in animal exposure and breastfeeding.
Overall, I have found evidence for 25 weak associations when looking at DNA methylation and eczema, and 24 CpG sites which could potentially show a link between risk factors and eczema. Replication and/or validation would strengthen results, as would a meta-analysis. Future work may potentially help design a treatment.