Previous studies reported that the encoded HOMER1 protein was involved in glutamatergic synapses and spine morphogenesis (Naisbitt et al. 1999; Tu et al. 1998; Hayashi et al. 2009; Govek et al. 2004), which suggested that the HOMER1 gene may be an important candidate gene in the etiology of MDD and suicidal behavior. This evidence concerns the gene HOMER1 and major depressive disorder.