C5orf20 is a intronless gene is specifically expressed in dendritic cells (DCs), which are potent antigen-presenting cells involved in activating naive T cells to initiate antigen-specific immune response. The encoded protein is localized mainly in the perinucleus. One of the alleles (A/T) of this gene, that causes premature translation termination at aa 117, has been associated with an increased prevalence of major depression in humans