Arabians, pure and part-bred
Friesians, pure and part-bred
Fell Ponies, Dale Ponies and Gypsy horses, pure and part-bred
Quarter horses and related breeds, pure and part-bred
Saddlebred and related breeds, pure and part-bred
Coat colour tests
Glycogen branching enzyme deficiency (GBED) can appear in pure and part-bred Quarter Horses and Paint horses. It affects newborn foals, and is always fatal. Signs of GBED include weakness, seizures, low body temperature and sudden death. GBED can also cause foals to be aborted.
GBED is an autosomal recessive disorder. Autosomal disorders are equally likely to affect male or female horses, while "recessive" means that a horse needs to inherit the GBED mutation from both its sire and its dam to be affected. Horses that have inherited the GBED mutation from just one parent are called GBED carriers, and do not have physical signs of this disorder.
Any GBED carrier can potentially produce a foal suffering from GBED. Fortunately this is easily avoided: you simply need to ensure that the prospective foal cannot inherit the LFS mutation from both its sire and its dam. Therefore, if you have a GBED carrier horse and it is mated to a GBED-clear horse there is no risk of the foal being affected with GBED.
GBED can be found in:
It is not currently known to occur in other breeds.