We used the single-maker association signals to follow up the results from the recent IOCDF-GC GWAS 21. For the markers listed in Table 1 of that study, we found evidence for association with a marker (rs2205748, same effect allele and direction of effect) on chromosome 6 near the genes GRIK2 (distance to gene 1.94 Mb) and the HECT domain and ankyrin repeat containing E3 ubiquitin protein ligase 1 gene (HACE1, 713 kb) with an uncorrected P-value of 0.0493 in our study (P=8.52×10−6 in the original IOCDF-GC trio-case-control analysis). One additional region (harboring the gene for the cAMP-specific phosphodiesterase 4D, PDE4D) showed a nominal significant signal; however, the effect (based on the same effect allele) was in the opposite direction (compared with the IOCDF-GC finding). Though no other marker among the tested SNPs from the IOCDF-GC GWAS reached a significant result, it is of note that, for the region around DLGAP1 an independent SNP in our analyses (rs3866988) yielded a P-value of 2.67×10−4 and thus indicating this region as a susceptibility factor for OCD (r2=0.023, D′=0.316 between rs3866988 and rs11081062/ rs11663827,
