Glycogen branching enzyme deficiency / GBED (GBE1-related) - Horse

What does this test examine?

This genetic test examines the GBE1 c.102C>A variant in horses. The condition is known as glycogen branching enzyme deficiency, GBED and glycogen storage disease type IV.

What does this mean for the foal?

GBE1 encodes the enzyme needed to branch glycogen correctly and store it in a usable form. Foals with two copies of the variant cannot form normal glycogen. This causes a severe energy and storage disorder that can lead to abortion, stillbirth, weakness, low body temperature, heart or breathing problems and rapid decline around pregnancy, birth or shortly after birth.

Practical value of this test

• The test identifies clear horses, carriers and genetically affected foals for GBED.
• Breeders can avoid carrier-to-carrier matings and prevent affected foals.
• The result provides valuable clarity in pregnancy loss, weak foals or breeding plans in Quarter Horse-related lines.

Inheritance

GBED is inherited as an autosomal recessive trait. Carriers have one copy and are usually healthy themselves; foals with two copies develop GBED.