Glycogen storage disease IX
Glycogen structure
Symptoms	Enlarged liver[1]
Causes	Mutations in PHKA1, PHKA2, PHKB, or PHKG2 genes[2]
Diagnostic method	CBC, Urinalysis[1][3]
Treatment	Physical therapy, follow metabolic nutritionist[1]

Glycogen storage disease type IX is a hereditary deficiency of glycogen phosphorylase kinase B that affects the liver and skeletal muscle tissue. It is inherited in an X-linked or autosomal recessive manner.^[1]

Signs and symptoms

The signs and symptoms in glycogen storage disease type IX include:^[1]

• Enlarged liver
• Slowed growth
• Motor development delay (mild)
• Low blood sugar accompanied by ketosis
• Lack of muscle tone

Most of these signs and symptoms diminish as adulthood sets in.^[1]

Genetics

Glycogen storage disease type IX can be inherited via:^[2][4]

• X-linked recessive inheritance due to mutations at either PHKA1 or the PHKA2 (most common^[5]) gene
• Autosomal recessive could be the inheritance pattern for an affected individual when the genes PHKB or PHKG2 have a mutation.

Diagnosis

The diagnosis of glycogen storage disease IX consists of the following:^[1][3]

• Complete blood count
• Urinalysis
• Histological study of the liver (via biopsy)
• Genetic testing
• Physical exam

Types

There are two types of this inherited condition, glycogen storage disease IXa1 and glycogen storage disease IXa2 that affect the liver of an individual.^[6] Mutations in PHKA2 have been seen in individuals with glycogen storage disease IXa2.^{[medical citation needed]}

Management

The management of Glycogen storage disease IX requires treatment of symptoms by frequent intake of complex carbohydrates and protein to combat the low blood sugar. A nutritionist will advise on suitable diets. Liver function is regularly monitored and problems managed as they arise. However, liver problems have only been successfully treated by a transplant. Routine checks of metabolism are needed to ensure blood sugar (glucose) and ketones are managed. Regular moderate exercise is beneficial, although over-vigorous exercise is to be avoided, especially in those with enlarged livers.^[1][7]