Methods: We applied HRHM to GS:SFHS, a large family and population based Scottish cohort (N=19,896). Single-SNP and haplotype-based association tests were used to localize the association signal within the regions identified by HRHM. Functional prediction was used to investigate the effect of MDD-associated SNPs within the regions.
Results: A haplotype block across a 24kb region within the TOX2 gene reached genome-wide significance in HRHM. Single-SNP and haplotype-based association tests demonstrated that five out of nine genotyped SNPs and two haplotypes within this block were significantly associated with MDD. The expression of TOX2 and a brain-specific LncRNA RP1-269M15.3 in frontal cortex and Nucleus accumbens basal ganglia, respectively, were significantly regulated by MDD-associated SNPs within this region. Both the regional heritability and single SNP-associations within this block were replicated in the UK-Ireland group of the most recent release of the Psychiatric Genomics consortium (PGC2-MDD). The SNP-association was also replicated in a depressive symptom sample that shares some individuals with PGC2-MDD.
Conclusion: This study highlights the value of HRHM for MDD and provides an important target within TOX2 for further functional studies.
- Regional heritability
- Haplotype block
- Genome-wide analysis