Decoding the Diseases Examined by AQHA's Six-Panel Test

The six-panel test is a diagnostic tool used to assess the genetic predispositions of horses. It's meant to discover if a horse has or is a carrier for certain hereditary diseases and traits.

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While the test is done primarily for American Quarter Horses, several genetic diseases detected by the six-panel test occur in other breeds. For AQHA breeding stock, the results are required for a horse's record and certificate of registration.

Glycogen Branching Enzyme Deficiency Disorder (GBED)

What is it? GBED is an autosomal recessive disease caused by a mutation of the GBE gene, which reduces the function of the glycogen branching enzyme. As a result, cardiac and skeletal muscle, the liver, and the brain cannot store or mobilize glycogen. Glycogen's primary function in the body is to provide energy to the muscles so without the ability to use it, a horse will experience muscle weakness and death.

Since it's a recessive mutation, a horse must inherit two copies of the mutated gene, from the mare and stallion to be affected.

Is it manageable? No, in all cases a horse born with this disorder will die, typically as a foal. Because of this, you may not want to breed a horse that's a carrier.

Hereditary Equine Regional Dermal Asthenia Disorder (HERDA)

What is it? HERDA is an autosomal recessive disease caused by a mutation in the peptidyl-prolyl isomerase B (PPIB) gene, which causes hyper-elasticity in the skin. HERDA causes collagen-the material that makes your skin stretch and return to place-not to form properly. This causes the horse's skin to injure easily, leading to severe scarring, open wounds, nicks, and scrapes. It's also sensitive to the sun. It may be unnoticeable until a horse starts training, when the saddle and tack cause severe skin damage.