A new gene mapping technique should greatly speed the work of geneticists involved in the international Human Genome Project, report researchers.Researchers at the University of Colorado Health Sciences Center have developed a method called "STS gene mapping". The method developed by Dr. James Sikela, PhD, and his team uses a mapping marker (a genetic "bar code" ) called an STS, which can be used to determine the chromosomal location of any segment of DNA. STS stands for 'sequence tagged sites'. In 1991, Sikela and associates showed how STSs could be rapidly generated from human genes so that each gene would have its own unique STS. Each STS could then be easily assigned to a chromosome, thus simultaneously mapping the corresponding gene. The team has now refined the technique, using new tools that have recently become available, so that a gene's exact location on a chromosome can be determined. Locating genes associated with specific diseases has traditionally been a slow and painstaking process. The first step is usually to determine the approximate location of a disease gene on one of the 23 chromosomes. However, each section of a chromosome may have several hundred genes on it, so each gene must be located and tested individually to determine which one triggers a disease. This approach can take several years to complete. In the case of Huntington's disease, for example, it took researchers 10 years to identify the gene after the first marker was discovered.