What Is Glycogen Branching Enzyme Deficiency In Horses?

Glycogen branching enzyme deficiency (GBED) is a disorder first recognized by clinicians at the University of Minnesota that causes muscle weakness in Quarter Horse and related breeds. The clinical presentation of this disease is variable. Late term abortion or stillbirth is described for GBED.

What does the glycogen branching enzyme do?

Glycogen branching enzyme 1 (GBE1) plays an essential role in glycogen biosynthesis by generating α-1,6-glucosidic branches from α-1,4-linked glucose chains, to increase solubility of the glycogen polymer.

How does glycogen branching enzyme deficiency occur?

GBED is caused by an autosomal recessive mutation to the GBE1 gene, which leads glycogen branching enzyme activity that is reduced to absent.

What is MH horse?

What is malignant hyperthermia? Malignant hyperthermia (MH) is a rare inherited autosomal dominant disease. It causes a life-threatening condition in susceptible horses triggered by anesthesia drugs (such as halothane, isoflurane, and succinylcholine), and occasionally by stress or excitement.

What bloodlines carry GBED?

Although popular in the past, the King bloodline is now known to be linked to GBED, or glycogen-branching enzyme disorder. This fatal disease has afflicted Quarter Horse foals for many decades.

Why is glycogen branching important for animals?

Glycogen branching is essential because it allows for increased water solubility and several sites to break it down; this allows for easy and quick glycogen utilization when it is broken down. Glycogen synthesis and breakdown correlate with high and low energy states, respectively.

How does glycogen affect the brain?

In the hippocampus glycogen plays a vital role in supplying the neurones with lactate during memory formation. The physiological processes that glycogen supports, such as learning and memory, imply an inclusive and vital role in supporting physiological brain functions.

Is GSD fatal?

Because they affect so many organ systems, GSD Type II (Pompe’s disease) and GSD Type IV (Andersen’s disease) are very hard to treat and can be fatal. Research into enzyme replacement therapy and gene therapy is promising, which may improve the outlook for the future.

Why is Andersen’s disease fatal?

In such cases, the disease course is typically characterized by progressive liver (hepatic) scarring (cirrhosis) and liver failure, leading to potentially life-threatening complications.

Which disease will happen if glycogen debranching enzyme is affected?

Deficiency of debrancher enzyme causes Glycogen Storage Disease (GSD) type III, an autosomal recessive disorder, characterized by tissue accumulation of abnormally structured glycogen.

What are the signs and symptoms of MH?

Symptoms

• Severe muscle rigidity or spasms.
• Rapid, shallow breathing and problems with low oxygen and high carbon dioxide.
• Rapid heart rate.
• Irregular heart rhythm.
• Dangerously high body temperature.
• Excessive sweating.
• Patchy, irregular skin color (mottled skin)

What is the mortality rate of MH?

When MH was first recognized as a complication of anesthesia, the mortality rate was 70-80% [6]. Nowadays, the mortality rate is estimated to be less than 5%, with early detection of MH episode, using capnography, prompt use of the drug dantrolene, and the introduction of diagnostic testing [7].

What disease is most associated with MH?

MH has been linked to a rare disorder of muscle called Central Core disease and King Denborough Syndrome, a rarer muscle syndrome. Additionally, patients with certain forms of muscular dystrophy may develop life-threatening disturbances and muscle destruction on exposure to the triggering agents for MH.

What are the symptoms of GBED in horses?

2. What are the signs of GBED?

• Abortion or still birth of a foal.
• Weakness and low body temperature at birth.
• Sudden death on pasture of foals from the heart stopping or from seizures (due to low blood sugar).
• High respiratory rate and weakness of the muscles used to breathe in foals.

How do you tell if a horse has the HERDA?

Signs of HERDA include stretchy skin, severe skin wounds and scarring along the back and withers. The American Quarter Horse Association requires all breeding stallions be tested for HERDA. There is no cure or treatment for horses with HERDA.

What is the most inbred horse?

In horses, only one breed, the Clydesdale, has an average level of inbreeding exceeding 25% (top, red line), whereas in comparision, about 75% of dog breeds were greater than 25%.

Is glycogen an enzyme?

Glycogen phosphorylase is the primary enzyme of glycogen breakdown. For the next 8–12 hours, glucose derived from liver glycogen is the primary source of blood glucose used by the rest of the body for fuel.

What is the function of glycogen in animals?

Glycogen is a homopolysaccharide found in the liver and muscles of animals, where it is used to store energy.

What does glycogen do in animals?

Glycogen is an extensively branched glucose polymer that animals use as an energy reserve. It is the animal analog to starch. Glycogen does not exist in plant tissue. It is highly concentrated in the liver, although skeletal muscles contain the most glycogen by weight.

What are the symptoms of glycogen depletion?

Signs and Symptom of Glycogen Depletion

• Decreased Strength and Power.
• Increased Rate of Perceived Exertion.
• Feeling of “Flatness” in Muscle Bellies.
• Increase Weight Loss (Water) Overnight.
• Lack of Recovery.
• Decrease Exercise-Performance During Longer Workouts.

How does glycogen affect the liver?

Glycogen is a main source of energy for the body. Glycogen is stored in the liver. When the body needs more energy, certain proteins called enzymes break down glycogen into glucose. They send the glucose out into the body.