Are certain individuals predisposed to depression? If so, can these individuals do anything to prevent the onset, or must they simply wait for the disorder to take hold and alter their lives? A recent Science Daily release explored a study of people with major depression. A large genetic study, it found that a duplicated region of DNA in chromosome 5 can predispose people to major depression. This gene plays a significant role in the development of nerve cells, demonstrating that disruptions to the neurotransmission networks can form a biological basis for depression. Hakon Hakonarson, M.D., Ph.D., director of the Center for Applied Genomics at The Children's Hospital of Philadelphia and lead researcher on the study noted that the copy number of variations discovered were exclusive to people who had depression. In addition, the variations were located in a gene region that was important in the signaling of brain cells. This study focused on the copy number variation (CNV) in major depressive disorder, which is a major psychiatric and behavioral disorder that is estimated to affect 16 percent of the population of the United States. CNVs are deletions or duplications of segments of DNA. While specific CNV is generally rare in a population, it can still exert a strong effect on an individual who also harbors the CNV in their genes. Hakonarson is hopeful that eventually, study findings may be incorporated into personalized medicine as the identification of causative genes could suggest future targets for drug development and can also help to predict the future risk of developing depression.