The significant locus (rs9825823, chr3: 61,082,153) maps to the intronic region of the fragile histidine triad (FHIT) gene, a tumor suppressor protein implicated in several cancers (36). FHIT is expressed in multiple brain regions (amygdala, anterior cingulate cortex, caudate nucleus, prefrontal cortex, hippocampus, and hypothalamus, http://www.gtexportal.org/home/gene/FHIT, accessed 10.07.2016). It plays an important role in oxidative stress and level of DNA damage (37), biological processes implicated in MDD (38, 39). FHIT is a circadian clock modifier gene (40) and has been related to daytime sleepiness (41), which may be salient to the etiology of depression.
