PAG-V: W32 - MICROSATELLITES FOR LINKAGE MAPPING AND THE MOLECULAR BASIS OF INHERITED DISORDERS IN THE HORSE

Plant & Animal Genome V Conference

Town & Country Hotel, San Diego, CA, January 12-16, 1997.

W32

MICROSATELLITES FOR LINKAGE MAPPING AND THE MOLECULAR BASIS OF INHERITED DISORDERS IN THE HORSE

MICKELSON, JAMES R(1), Stephanie J Valberg(2), Esther M Gallant(2), Elizabeth M Santschi(2), Jennifer M MacLeay(2), Linnea R Lentz(2)
1. Department of Veterinary PathoBiology, College of Veterinary Medicine, University of Minnesota, 295 An.Sci./Vet.Med, St. Paul, MN 55108
2. Department of Clinical and Population Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108

Microsatellite (MS) markers for equine genetic linkage map development have been identified by constructing a small insert genomic DNA library and screening it for GT repeat sequences. To date, PCR primers to amplify 16 different polymorphic equine MS have been identified and accepted for publication. Plans are underway to genotype many of these MS markers on the International Reference Family. Approximately 100 more clones, each screening positive three times for a GT repeat, are awaiting sequencing, PCR primer development, and demonstration of polymorphism. We are also developing resource families and testing candidate genes at a biochemical, physiological and molecular basis for polysaccharide storage myopathy (PSSM), recurrent exertional rhabdomyolysis (RER), and overo lethal white syndrome (OLWS) in horses. PSSM in Quarter Horses appears to be inherited in an autosomal recessive fashion and is likely due to a metabolic defect. PSSM is characterized by high levels of glucose 6-phosphate and glycogen and the accumulation of an abnormal polysaccharide in muscle fibers; however, no deficiency in any glycolytic enzyme has yet been found in affected horses. One form of RER in Thoroughbreds also appears to be an inherited disorder originating within popular bloodlines. The molecular basis for RER appears to be a defect in the excitation-contraction coupling mechanism of skeletal muscle. Lastly, OLWS (intestinal aganglionosis) is being examined in Paint horse families with the overo coat pattern. Genes associated with analogous conditions in humans and rodents are being cloned and sequenced in control and affected foals to identify possible mutations associated with the lethal syndrome or the overo pattern.