Summary

In the late 1970s, geneticists were working to map the inheritance and location of genes that cause specific illnesses, such as hemochromatosis. To do so, researchers endeavored to pinpoint a gene's location on a chromosome and identify it based on other genes that are always associated with it. For example, if the hemochromatosis gene is linked to a gene that specifies hair texture, a statistical pattern between those physiologies can be mapped and the location of the hemochromatosis gene can be identified. Researchers began to look for other such genetic "signposts" that might indicate gene locations. The possibility of mapping the human genome began to seem more realistic.

Around the same time, a woman named Nancy Wexler, whose family has a history of Huntington's disease, set out on a mission to identify and map the...