Every human being has twenty-three chromosomes and thousands of genes. Precision medicine aims to assess risk and customize treatment for specific genetic variants and disease characteristics associated with these human building blocks. Large databases of genetic information are needed to locate the best targets for specific therapies. This month's DataGraphic focuses on precision medicine's rapid growth in the past two decades in genetic tests and therapies and its successes in prolonging life and cutting some costs. It also highlights challenges ahead due to the high cost of therapies, the limited representation of racial and ethnic minorities in genetic databases, and uncertainty among professionals about how to apply genetic findings.