GSD Type 1X
Deficient enzyme Phosphorylase Kinase

In both GSD type VI and GSD type IX there are low levels of G1P and therefore low blood levels of glucose.


With your body potentially having low levels of glucose, your body needs to produce energy in other ways. One way to do this involves the body using its fat stores to produce ketones. The body can also start to use protein to produce energy. 


Ketones are an alternative source of energy. In healthy individuals, ketone levels are typically very low. Extended fasting can lead to higher levels of ketones. Ketones are produced from the body’s fat stores. The brain needs a lot of energy to work properly but it cannot use fat to produce energy – it prefers glucose. However, the brain can get energy from ketones. If you have GSD type IX, turning fat into ketones helps your brain get energy when glucose levels are low. Ketones also help keep your muscles supplied with energy when your glucose levels are low. Although ketones can be a very useful source of energy, it is important that your ketone levels do not go too high. High ketone levels indicate that GSD control could be better.


Good dietary management aims to reduce the risk of your blood glucose levels going too low. This means that your body will not need to make ketones or break down your muscles to produce energy.

GSD type IX can be very variable in terms of severity. Some individuals are prone to regular ‘hypos’ whereas other individuals, without treatment, will show poor growth and an enlarged liver but don’t tend to get ‘hypos’. 
Like GSD type VI, type IX is often viewed as a milder form of GSD. If you have GSD type IX, it is still very important that you attend all your clinic appointments and follow the advice given to you by your Specialist Metabolic Team.