Examining significant genes that overlap between the current meta-analysis of depression and the neuroticism studies of both Luciano, et al. 18 and Okbay, et al. 19 revealed putative associations with DRD2, CUGBP Elav-like family member 4 (CELF4) and ELAV like RNA binding protein 2 (ELAVL2). Dopamine acts as a neurotransmitter in the brain with DRD2 encoding the dopamine receptor D2 subtype. Supporting evidence of the importance of the cortical brain regions was provided by the heritability partitioning of the brain regions (Figures 2B and 2C) with significant enrichment of the anterior cingulate cortex, frontal cortex and cortex brain regions. DRD2 is also associated with mood modulation and emotion processing20 and is reported in association studies of schizophrenia21. DRD2 was included in all 14 of the putative Gene Ontology Consortium gene-sets identified (but not the somatosensory pyramidal neurons gene-set) and has been identified in previous studies of depression5, 9, 22. CELF4 plays a key role in coordinating the synaptic function in excitatory neurons23 with dynamic changes in expression during brain development and deletions in the surrounding region (18q.12.2) associated with developmental
