A gene disease database is a collection of information about genes and diseases. Genes are tiny pieces of code inside our cells that contain instructions for how our bodies work. Diseases are illnesses or health problems that affect us. The gene disease database keeps track of which genes are linked to which diseases. For example, there could be a gene linked to heart disease and another gene linked to diabetes. By looking at the database, doctors can learn more about what kinds of things can make us sick.