Glycogen Branching Enzyme Deficiency (GBED)

Glycogen Branching Enzyme Deficiency, "GBED", is a fatal disease that is seen in Quarter Horses and related horses. Affected animals may be aborted or stillborn, and foals that survive to term typically die or cannot stand or nurse on their own. Foals may appear healthy for a time but eventually may develop seizures, become too weak to stand, or in some cases, die suddenly.

GBED affected horses lack an enzyme that is used to properly make the necessary sugars muscles need to function. Affected horses cannot store the sugar needed for numerous tissues in the body. This means the tissues are energy impaired, resulting in muscle weakness and organ failure.

Approximately 10% of quarter horses are carriers of GBED, most commonly found in western pleasure and cutting horse industries.

GBED is a recessive mutation. This means that a horse must inherit TWO copies to be affected. A horse that inherits one copy, known as a carrier, will not experience symptoms of the disorder but can pass the mutation on to offspring.