DNA

Medical genetics research seeks to find and study the genetic causes of human diseases.^[48] When searching for an unknown gene that may be involved in a disease, researchers commonly use genetics linkage and genetic pedigree charts to find the location on the genome associated with the disease. At the population level, researchers take advantage of Mendelian randomization to look for locations in the genome that are associated with diseases, a technique especially useful for multigenic traits not clearly defined by a single gene. Once a candidate gene is found, further research is often done on the same gene (called an orthologous gene) in model organisms.

Although many inherited diseases are subjects of genetic research, cancer is also considered a genetic disease.The process of cancer development in the body is a combination of events. Mutations occasionally occur within cells in the body as they divide — while these mutations will not be inherited by any offspring, they can affect the behavior of cells, sometimes causing them to grow and divide more frequently. There are biological mechanisms that attempt to stop this process — signals are given to inappropriately dividing cells that should trigger cell death, but sometimes additional mutations occur that cause cells to ignore these messages. An internal process of natural selection occurs within the body and eventually mutations accumulate within cells to promote their own growth, creating a cancerous tumor that grows and invades various tissues of the body.