Gene-based statistics were derived as fixed Z scores, as implemented in FORGE 30. More information on the approach is provided elsewhere 31. Here we used the single-marker results of our combined OCGAS GWAS. Information about the correlation pattern in the data was provided through usage of HapMap phase 2 samples 32. A maximum of 1 000 000 permutations were used per gene (adaptive approach) and analyses included an additional +/− 20kb sequence information based on positions obtained from ENSEMBL v70 33. We used the gene-based results in two ways: First we used them to agnostically search for genes that are associated with OCD. Second, we used them to follow-up on gene-set based results from the IOCDF-GC study, which reported an enrichment of association signals for two gene sets that comprised high confidence targets of two miRNA families 21. In addition, we used information from a global interactome for Homo sapiens in order to identify high confidence interactors of DLGAP1 and GRIK2 (confidence threshold > 0.95) 34. No sub-network reduction was applied and only genes representing first neighbors of DLGAP1 and/or
