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Your GSD9 coordinator is
Dan Machin


GSD9 is now recognised as one of the more prevalent forms of GSD, accounting for 25% of all people affected by GSD.

There are four variants, sometimes known as a, b, c and d, but now going by the names of:
• PHKA2 (formerly a). This is carried on the X part of the gene and is normally seen in males, however some female carriers are affected. Some 75% of people with GSD9 have this liver variant.
• PHKB (formerly b). Only 20 people have been reported to have this type which affects the liver and muscles.
• PHKG2 (formerly c). This is a recessive form of GSD9 with liver and muscle symptoms.
• PHKG1 (formerly d and PHKA1). This primarily affects the muscles.

Main signs of most GSD9 sub-type

  • An enlarged liver (hepatomegaly) due to increased glycogen storage
  • Hypoglycaemia (problems with maintaining blood sugar).

Muscle problems are present in some variants. A major feature is the wide variety of symptoms from person to person.

The information for this webpage came from this article which can be accessed here. (The paper does not cover the PHKG1 / GSD9d muscle form.)
View the paper on GSD6 and GSD9.

Muscle type PHKG1 / GSD 9d

For this form, please see the panel in the diagnosis and follow up section.


Other names

Glycogen phosphorylase b kinase deficiency

Affected Liver and muscle forms

X-linked and autosomal recessive patterns

Incidence Approx. 1 in 100,000
UK diagnosed About 150  (UK diagnosed explained)

Hypoglycaemia, hepatomegaly and muscle problems

Secondary symptoms

Secondary symptoms are varied but might include growth retardation, sleep difficulties with overnight irritability, ketosis and hyperlipidaemia


Symptoms are managed


Generally good but further studies are needed


How can we help?


Diagnosis & Follow up

Diagnosis, Parents’ guide, Diagnosis and Management guidelines


Information & Support

Coordinator, Social media, GSD & Me web site, Links


Activity & Exercise

Nothing available in this section yet

Research & Development

About clinical trials

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