When you know the genetic mutations that cause a disease, you may be able to intervene to lessen the disease's effects. And you may also be able to develop genetic tests for the mutations so that people can learn if they are more likely to develop a disease, or if they are carriers of the trait and may pass it on to their children.
Searching for the genes involved in a genetic disease involves discovering which gene has been mutated and how it has been mutated. Because there may be more than one mutation in a gene which can cause a genetic disease, the search is often long. To intervene in the disease, you have to know what the gene is supposed to do, and what it isn't doing.
One way researchers discover which genes go with what disease is through a technique called linkage analysis. By sampling DNA from families with many cases of a genetic disease, researchers can compare the DNA of affected family members to the DNA of family members who don't get the disease. Similar DNA segments in affected relatives mark specific chromosomes where scientists should search for the gene.
Here are the stories of four genetic diseases. Click on one to learn more.
Revolution in Progress: Human Genetics and Medical Research/
Institutes of Health