DNA Changes: Gene Sequence Or Gene Activity

There are at least two ways a change in DNA can affect a person’s appearance or behavior. One involves mutation—when an alteration in the gene sequence modifies the protein made by that gene. A single mutation in one gene can cause diseases like cancer or sickle-cell anemia. Epigenetics is a more recently discovered way that genes can be altered. Instead of a gene mutation, the gene’s activity is increased or decreased. For example, molecules called methyl groups can be attached to a gene, which diminish its activity. If a gene becomes heavily methylated, it can be completely shut down.