The Sciences How Trivial DNA Changes Can Hurt Health Small changes to DNA that were once considered innocuous enough to be ignored are proving to be important in human diseases, evolution and biotechnology By J. V. Chamary and Laurence D. Hurst THIS IS A PREVIEW. Buy this digital issue or subscribe to access the full article. Already a subscriber or purchased this issue? Sign In Jon Krause Biologists long thought they understood how genetic mutations cause disease. But recent work has revealed an important twist in the tale and uncovered surprising—even counterintuitive—ways that alterations in DNA can make people sick. The classic view assumed that what are termed “silent” mutations were inconsequential to health, because such changes in DNA would not alter the composition of the proteins encoded by genes. Proteins function in virtually every process carried out by cells, from catalyzing biochemical reactions to recognizing foreign invaders. Hence, the thinking went, if a protein’s makeup ends up being correct, any small glitches in the process leading to its construction could not do a body harm. Yet detective work occasionally traced a disorder to a silent mutation, even though researchers presumed that it could not possibly be the culprit. Similar mysteries popped up in studies of genome evolution, where patterns of changes in the DNA of various species indicated that many silent mutations were preserved over time—a sign that they were useful to the organisms possessing them. In many species, these changes seemed to help cells make proteins more efficiently, but not in people. THIS IS A PREVIEW. Buy this digital issue or subscribe to access the full article. Already a subscriber or purchased this issue? Sign In Buy Digital Issue $7.99 Add To Cart Print + DigitalAll Access $99.99 Subscribe ADVERTISEMENT Scientific American is a trademark of Scientific American, Inc., used with permission © 2015 Scientific American, a Division of Nature America, Inc. All Rights Reserved.