Glycogen storage disorders (GSD) are a group of potentially life-threatening genetic disorders present from birth.
Glucose, a type of sugar, is the main source of energy for the body. It is stored in the form of glycogen in both the liver and muscles and later released with the help of enzymes when we don’t eat for a stretch of time-like when we miss a meal or when we sleep. Persons with GSD have a defect in one of the enzymes responsible for making or releasing glycogen when it is needed and this can lead to low blood sugars, called hypoglycaemia.
There are at least ten distinct types of GSD. They are classified by a number and by the name of the defective enzyme. Depending on the type, some GSD can affect the liver, the muscles or both.
At present, the treatment for most GSD, is to have frequent carbohydrate meals and snacks to avoid low blood sugars. Tube feeding may be recommended in some types of GSD in early infancy and childhood. Patients may be recommended to take uncooked cornflour or another long acting starch called Glycosade to allow them to fast for longer. Each patient will have an individualised plan that is developed by the doctors and dietitians to prevent hypoglycaemia when well.
During times of illness, the body will break down its own tissue to provide energy (catabolism). This can be dangerous for people with GSD as glucose may be used up more quickly. Patients will have an individualised emergency plan to use when they are unwell. Tube feeding or an intravenous infusion of glucose may be required when unwell to prevent hypoglycaemia.
GSD III is most common type of GSD seen in Ireland but symptoms vary widely in severity within this type.
At NCIMD, we have been treating patients with GSD for a number of decades and have significant experience of managing these disorders. Patients with GSD are managed by the multidisciplinary team and we liaise closely with the Metabolic Laboratory to ensure close monitoring of these patients. We follow international best practise guidelines in management of the different types of GSD. We have also published papers in international medical journals as well as presenting our experience of management of GSD at various international conferences.
Diet for GSD III booklet-coming soon