Group Leaders: Alison Ashley-Koch PhD and Mike Hauser PhD
The PGC–PTSD Gene Expression Workgroup has, as its goal, the identification of genes that are differentially expressed in controls and individuals with current PTSD. Multiple smaller studies have been conducted; however, these studies frequently suffered from low power. The full PGC- PTSD consortium will generate gene expression data on several thousand individuals, greatly improving power. This data set can be also used in conjunction with multiple other types of ‘omics data, including DNA methylation and genome wide genotype data. This will allow multiple cross-platform analyses to be performed. For example we will have sufficient power to conduct eQTL analyses to identify genetic variants that can alter the level of expression of specific genes. Likewise, we will be able to identify DNA methylation patterns that may be giving rise to altered gene expression. Such joint analyses of multiple –omics datasets have been previously termed “genomic convergence” and have great potential to inform us about the genetic architecture of PTSD. The working group has several challenges to consider. First, multiple platforms have been used for gene expression analysis—Affymetrix arrays, Illumina arrays, and RNAseq. Combining these data into a single analysis will require the development of new methods. Further, so expression datasets will not have associated GWAS or methylation data, making it harder to correct for population structure and cell type composition of blood samples. The working group will use multiple approaches to address these challenges.