Gene Hunters' Next Challenge

Courtesy of Kevin Becker

Four different autoimmune diseases map to the same 10cM region on the long arm of chromosome 16.

Common, complex diseases such as diabetes, asthma, and cardiovascular conditions are the next challenge gene hunters face. These researchers have successfully identified many rare Mendelian disorders that are caused by mutations in one gene. But common diseases are difficult to study because they don't segregate in a Mendelian fashion. Although common diseases tend to cluster within families, they are influenced by an interaction of environmental factors and multiple genes. Researchers are hoping that the progress of the Human Genome Project and the development of a genomewide map of single nucleotide polymorphisms (SNPs) will eventually provide the necessary tools to unravel complex diseases.

Analytical strategies that have successfully mapped the rare monogenic disorders have not definitively identified any genes involved in complex diseases. Traditionally, linkage studies have been useful for...