A new research tool, developed at the University of Southern California (USC) by molecular biologist Dr. Norman Arnheim and mathematician Dr. Pavel Pevzner, promises to speed the hunt for disease-causing genes. Genes are buried in human chromosomes in large volumes of DNA, often called Ajunk@ DNA, that does not carry messages for specific products. Individual genes are broken up by this Ajunk@ DNA into as many as 50 segments called Aexons,@ that are spaced over a long stretches of chromosome DNA. Exons are joined into a continuous gene message when a gene goes into use. Groups of suspected disease causing genes can be isolated by examining all the gene messages from large regions on chromosomes. However, to find disease-causing forms of genes requires a comparison of genes from different people, an understanding of how genes are broken up into exons, and information on the DNA sequence found at the exon/Ajunk@ DNA borders. This information can be determined by comparing the DNA sequence of gene messages and the original DNA, containing both gene messages and Ajunk@ DNA, but is expensive and laborious. This is where the new USC technique comes into play. The technique resembles a game of A20 Questions@ in which a series of Ayes@ or Ano@ answers is used to narrow the possibilities and solve a riddle. In this case, the riddle is to find the distance between two specific DNA sequences that are part of a gene of interest. The distance between two specific DNA sequences can differ in chromosomal DNA and in a gene message because of the Ajunk@ DNA in the chromosomal DNA. If distances between two test sequences are greater in chromosomal DNA it is assumed that the test sequences are in different exons. By repeating the process with different test sequences, the boundaries of the exons can be narrowed down. On average, 30 of these Aquestions@ can reveal the locations of individual exons in a gene message. AWe believe that the technique will greatly speed the identification of mutations, with direct applications for research into genetically based human disease,@ says Arnheim. The research was funded by grants from the U.S. Department of Energy, the National Institutes of Health, and the National Science Foundation.