To the Editor: Serotonergic function has long been thought to be important in mood regulation, and first-line treatments for mood disorders involve the use of selective serotonin reuptake inhibitors. There are numerous receptors for serotonin in the brain, and most have been investigated in candidate gene studies or gene expression studies using blood or brain samples from mood disorder patients or those who have died by suicide. One particular brain receptor for serotonin, 5HTR1A, has been studied thoroughly with conflicting results: some studies suggest increased expression or binding in the frontal cortex and rostral raphe of suicide completers (1, 2), while others show decreased expression or binding in the brains of depressed subjects (3). Nevertheless, all studies suggest that altered expression of 5HTR1A may have a role in suicidal behavior and mood. We identified one individual recruited in the Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD) cohort (4) with a 617,395 Kb duplication on chromosome 5 (Hg18: 63166781–63784175) that included a complete duplication of the 5HTR1A gene (Figure 1A). We validated this duplication with quantitative real-time polymerase chain reaction using three independent probes across the copy number variant (CNV) comparing the patient’s DNA to seven control samples without a CNV at this locus (Figure 1B). There were no other rare CNVs in this individual within the detection resolution of this technology.