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Glycogen Branching Enzyme Deficiency - GBED

Glycogen Branching Enzyme Deficiency - GBED

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DNA test
  • DNA test for the Glycogen Branching Enzyme Deficiency (GBED). This test verifies the presence of the recessive GBED gene.


  • 20 to 30 - hair roots - envelope
  • 5 mL - blood - K3 EDTA tube

Turnaround time

  • 2 to 5  working days

Why test?

  • This genetic test helps breeders to identify horses that carrying the GBED recessive mutation. Informed choices can be made for breeding selections, and prevent the born of affected foals.

Results description

The DNA test verifies the presence of the recessive GBED gene and presents results as one of the following: 

  • N/ - Negative for GBED. Absence of the defective gene responsible for GBED.
  • N/GBED - Positive heterozygous for GBED - carrier. Presence of a mutated allele responsible for GBED.  The horse is a carrier for the GBED mutation and can pass on a copy of the defective gene of their progeny when bred.
  • GBED/ -  Positive homozygous for GBED. Presence of two mutated alleles responsible for GBED.  The horse is affected with the GBED and will pass the GBED allele to 100% of its offspring.

Additional information

Glycogen Branching Enzyme Deficiency (GBED) is a fatal condition caused by the bodies' inability to properly store sugar. In a normal horse, the body stores sugar as energy by converting glucose to glycogen. This inherited disorder prevents the body from producing the enzyme needed to branch the glycogen structure, preventing the horse from being able to adequately store the sugars. This means that the horse will not be able to store enough energy to fuel important organs, such as the muscles and brain.

Foals born which are affected by GBED suffer from a range of symptoms associated with this lack of fuel, such as low energy, weakness and difficulty rising. Other symptoms include low body temperature, contracted muscles, seizures, and sudden death. Unfortunately, GBED is always fatal; most affected foals will die before the age of 8 weeks. GBED often causes the foetus to be aborted in utero. Research suggests that as many as 3% of aborted Quarter Horse foals were homozygous for the GBED mutation.