Gene Mapping Compiled by Deirdre B. Biles, The Blood-Horse, Vol. CXXV, No. 29, July 17, 1999. Copyright 1999 THE BLOOD-HORSE, INC. All rights reserved. An international effort to create a gene map for the horse is making progress. Scientists who attended a mapping workshop in early June in Sweden repored that 238 markers had been testsed so far in a project designed to develop a 300-marker linkage map based on an international set of reference families from a variety of breeds. Testing on all 300 markers is scheduled to be completed by Aug.31. According to Dr. Ernie Bailey of the University of Kentucky, the 300-marker map is widely regarded as the minimum map coverage necessary to detect linkage relationships between markers and genes of interest. Genetic markers have been identified on each chromosome of the horse. The next goal may be a 500-marker map, and a new tool under development, the radiation hybrid panel, could enable resarchers to map 1,000 genes and genetic markers by 2001. Scientists from around the world first began pooling their equine gene mapping resoures in 1995. The effort has included several international workshops that have been conducted with the help of funding from the Dorothy Russell Havemeyer Foundation. The next workshop is scheduled for January of next year in Southern California. -Compiled by Deirdre B. Biles