Glycogen branching enzyme deficiency (GBED)

Affected foals lack the enzyme GBE that is necessary for synthesis and storage of glycogen. Predominantly affected are sceletal muscle, brain and heart. Clinical signs associated with GBED are: Abortion, dead or weak foals; sudden death due to heart failure and or seizures; tachypnoa due to weak sceletal muscle (diaphragm); generalised weakness, especially when getting up. There is no treatment available yet and up to now affected foals died or had to be euthanized. Until recently GBED has not been recognized as a disease, mainly because the clinical signs are very similar to other diseases that typically affect foals. Furthermore, routine staining of muscle tissue post mortem was not suitable to detect GBED. After the development of a genetic test to identify the mutation responsible for GBED, epidemiological studies revealed that about 10% of the horses belonging to QH, Paints and related blood lines carry the mutation. It is suspected that about 3% of the abortions of QH are due to this disease.