Glycogen Storage Disease Type XV

What else is it called?

  • GSD type 15 
  • GSD type XV 
  • GSD with severe cardiomyopathy due to glycogenin deficiency  
  • Glycogen storage disease type 15 
  • Glycogen storage disease type XV 
  • Glycogenosis type 15 
  • Glycogenosis type XV 
  • Glycogenosis with severe cardiomyopathy due to glycogenin deficiency  

Get in touch

Contact our caring team on 08452 412 173 for help and support. Our phone lines open 10am-4pm, Monday to Friday.

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What causes it?

GSD type 15 is caused by mutations in the GYG1 gene. This gene is responsible for encoding (converting) the enzyme, glycogenin. These mutations lead to muscle weakness and cardiomyopathy (a disease of the heart muscle making it harder for the heart to pump blood to the rest of the body)

How common is it?

Glycogen storage disease type 15 is an extremely rare genetic glycogen storage disorder that has only been reported in one patient to date. The estimated prevalence of the condition is less than 1 in 1,000,000 

What are the signs and symptoms?

Clinical signs first started in childhood in the one case that has been reported and included: 

  • Muscle weakness 
  • Cardiac arrhythmia (irregular heartbeat) 
  • Cardiomyopathy (a disease in the heart muscle that makes it harder for you heart to pump blood to the rest of the body) 
  • Accumulation of abnormal storage material in the heart  
  • Glycogen depletion (running out of glycogen stores) in the skeletal muscles 

How is it diagnosed?

A diagnosis of Glycogen Storage Disease Type 15 can be confirmed through genetic testing which will show mutations in the GYG1 gene.  

Can it be treated?

Treatment for this condition are symptomatic & supportive. They aim to manage and alleviate individual symptoms and provide support for the patient and their families.  

Do my family need to be tested?

Glycogen storage disease type XV is an inherited condition. Humans have chromosomes made up of DNA. Genes are pieces of DNA that carry the genetic information. Each chromosome may have several thousand genes. We inherit chromosomes from the egg of the mother and sperm of the father. The genes on those chromosomes carry the instructions that determine a person’s characteristics, which are a combination of the parents. 

The pattern of inheritance of glycogen storage disease type XV is autosomal recessive. This means that carriers of the condition do not have the disorder because the other gene of this pair is working normally. Parents of children with glycogen storage disease type XV are carriers.   

When both parents are carriers, the risk to the baby in each pregnancy is 

  • 25% chance (1 in 4) of developing the condition 
  • 50% chance (1 in 2) for the baby to be a carrier of the condition 
  • 25% chance (1 in 4) for the baby to have two working genes and neither have the condition nor be a carrier 

Genetic counselling can be requested to get a full explanation.  

Relevant Organisations

For more information, please visit Association for Glycogen Storage Disease UK.


References are available on request. Please contact Helen Morris by phoning 0845 241 2173 or emailing [Resource Library No: AAP002]. 

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