Because the disease is autosomal recessive, affected foals must be homozygous for the lethal GBED allele, meaning both parents must be heterozygous for the allele. A blood test for this allele was developed by the University of Minnesota College of Veterinary Medicine and is licensed to the UC Davis Veterinary Genetics Laboratory. Using this, breeders can avoid crosses that could produce GBED foals, and eventually selectively breed it out. Carrier frequency has been estimated at 7.1% in the Quarter Horse, 8.3% in the Paint Horse, and as high as 26% in Western Pleasure horses.
