DNA, which has a double-helix structure, can have many genetic mutations and variations. Credit: NIH New research led by King's College London has found that thousands of DNA sequences originating from ancient viral infections are expressed in the brain, with some contributing to susceptibility for psychiatric disorders such as schizophrenia, bipolar disorder, and depression. The work appears in Nature Communications. About 8% of our genome is comprised of sequences called Human Endogenous Retro...