The markers could help researchers track down the genetic causes of complex diseases such as heart disease and cancer.
Genetic markers are like signposts that help researchers find their way around the DNA landscape.
The markers that Kwok and colleagues intend to find are places on chromosomes where single letters in the genetic code can vary. The change from one letter to another usually doesn't affect a person's health, but locating such variations gives researchers crucial information in their search for genes. If people with a given disease carry the same letter at a marker site, the gene that causes that disease probably lies near that marker. This concept already has led to the discovery of many disease-causing genes, such as that for cystic fibrosis. But to find the genes that contribute to diseases such as heart disease, cancer, diabetes and many psychiatric disorders, researchers need many more markers.